LIT-006-00 – Operation Maintenance Service Manual – 9,000 – 15,000 Lbs. Axle Capacity – Dexter

SEOCONTENT-STARTIntroduction
This manual is designed to provide information for you to understand,
use, maintain, and service your trailer running gear system. Your axles are
manufactured by Dexter. Since 1960, Dexter’s experience in the design,
testing, and manufacturing of trailer axles has resulted in the most complete
product line in the industry. The Dexter running gear system consists of
axles, suspensions, and braking systems which are engineered to provide
you the finest towing and stopping performance available today.
Two Dexter philosophies are at work to provide you the best product
available and have enabled us to maintain our position of leadership. First,
we operate on the theory that “there is always a better way” for a product
to operate, to be manufactured, and/or to be serviced. We are constantly
striving to find that better way.
Secondly, we maintain the highest quality control standards in the
industry and adhere to ISO 9001:2015. Dexter has operated with detailed
documented processes and procedures long before completing ISO
Certification, continually placing quality and customer service as the
focus. This ensures that critical components including axle beams, hubs,
drums, spindles, and braking systems are manufactured to the highest
quality standards so that we can provide our customers with dependable
products, the most comprehensive product offering and reliable, consistent
customer service.
Trusting is hard. Knowing who to trust even harder. Through vertical
integration we engineer, design, manufacture and test virtually every part
in-house to ensure superior quality trailer running gear. We fuss over
details, so you don’t have to. Trust Dexter.
Visit us online at www.dexteraxle.com.Table of Contents
-4-
Introduction
Maintenance Schedule
Item Function Required Weekly
3 Months or
3,000 Miles
6 Months or
6,000 Miles
12 Months or
12,000 Miles
Brakes
Test that they are
operational.
At Every Use
Brake
Adjustment
Adjust to proper operating
clearance (not required with
Nev-R-Adj® brakes). •
Brake Magnets
Inspect for wear and current
draw. •
Brake Linings
Inspect for wear or
contamination. •
Brake Controller
Check for correct amperage
and modulation. •
Brake Cylinders Check for leaks, sticking. •
Brake Lines
Inspect for cracks, leaks,
kinks. •
Camshaft
Bushings
Check for wear and
breakage. •
Anchor Pins
and Rollers
Lubricate with approved
grease. •
Slack Adjuster
Lubrication
Lubricate with approved
grease. •
Trailer Brake
Wiring
Inspect wiring for bare
spots, fray, etc. •
Breakaway
System
Check battery charge and
switch operation.
At Every Use
Hub/Drum
Inspect for abnormal wear
or scoring. •
Wheel Bearing
and Cups
Inspect for corrosion or
wear. Clean and repack. •
Seals
Inspect for leakage.
Replace if removed. •
Springs
Inspect for wear, loss of
arch. •
Suspension
Parts
Inspect for bending, loose
fasteners and wear. •
Extreme Duty
Bushings
Grease. •
Hangers Inspect welds. •
Wheel Nuts
and Bolts
Tighten to specified torque
values. •
Wheels
Inspect for cracks, dents, or
distortion. •
Tire Inflation
Pressure
Inflate tires to mfg’s.
specifications. •
Tire Condition
Inspect for cuts, wear,
bulging, etc. •
-5-
Important Safety Notice
Appropriate service methods and repair procedures are essential
for the safe, reliable operation of all running gear as well as the
personal safety of the individual doing the work. This manual
provides general directions for performing service and repair work
with tested, effective techniques. Following these guidelines will
help assure reliability.
There are numerous variations in procedures, techniques, tools,
parts for servicing axles, as well as in the skill of the individual
doing the work. This manual cannot possibly anticipate all such
variations and provide advice or cautions as to each. Anyone who
departs from the instructions provided in this manual must first
establish that they neither compromise their personal safety nor
the vehicle integrity by their choice of methods, tools, or parts.
Refer to your vehicle manufacturer’s owners manual for additional
procedures, techniques, and warnings prior to performing any
maintenance or repairs.
! CAUTION
This is the safety alert symbol. It is used to alert you to
potential injury hazards. Obey all safety messages that
follow this symbol to avoid possible injury or death.
Getting Started – Setup and Adjustment
For proper performance, all new axles should have the following
checked at the specified intervals:
• Wheel Nut Torque: at 10, 25, and 50 miles
• Brake Adjustment: at 200 and 3,000 miles
• Tire pressure: to manufacturer’s requirements
• Brake synchronization: set brake controller per controller
manufacturer’s directions
Introduction
-6-
Answers to Commonly Asked Questions
Q: Why do my brakes and hubs get so hot?
A: Braking systems use friction to slow the vehicle and the
energy used to retard the trailer is converted to heat.
Dexter brakes are designed to operate up to extremely high
temperatures during hard braking application. This heat
is noticeable on the hub and drums and is to be normally
expected on a properly functioning brake. If a brake is
malfunctioning and running excessively hot, this can be
noticed by smoking brakes or the paint burning off of the
brake drum. If this occurs, refer to the brake troubleshooting
diagram for your type of brake.
Q: Why do I have to adjust my brakes?
A: Brakes must be adjusted to compensate for the lining and
drum wear that occurs during use of the braking system.
Some brakes require manual adjustment to move the linings
closer to the drum. Refer to the brake adjustment section for
your style of brakes. Other brakes may have an automatic
brake adjuster such as the automatic slack adjusters for air
brakes.
Note: Prior to 10/96 electric and hydraulic self-adjusting
brakes adjust only during hard, reverse stops. If your driving
does not include these types of stops, you will have to
manually adjust your brakes. Designs after 10/96 adjust both
in forward and in reverse. Adjustment in reverse still requires
hard stops, while adjustment in forward motion will occur
through normal driving.
Q: My brake linings are cracked, do I have to replace them?
A: Usually, light cracking of the surface of a brake lining
can be expected under normal use. This is not cause for
replacement. However, if the lining is missing chunks, your
brake linings or shoes will require replacement.
Q: Why do I have to torque the wheel nuts on my trailer and do
not have to do so in my car?
Introduction
-7-
A: The main reason is wheel capacity. Your entire car may
weigh 3,000 lbs. which is spread over four wheels, while
a 6,000 lb. trailer axle has 3,000 lbs. on a single tire
and wheel. This places greater stress on the wheel/tire
combination. The second reason is loading. Your car
is designed to have the wheels track the arc of a turn,
reducing side load on the tire and wheel. Trailers are
subjected to harsh side loads, especially in double and triple
axle configurations. These side loads work to flex the wheel
which may cause the wheel to lose torque over time. Please
follow the wheel usage instructions located later in this
manual.
Q: Why can’t I lock and slide my electric brakes?
A: On an unloaded trailer, you may be able to lock up your
brakes if your electric brake controller is supplying full
amperage to the brakes. When loaded to capacity, you
may not be able to lock your brakes as electric brakes are
designed to slow the trailer at a controlled rate, and not
designed to lock up the wheels on a fully loaded trailer. Our
brakes are designed to meet all applicable safety standards.
All of our brakes will perform better after numerous burnish
stops to seat the brake linings to the drums.
Q: I don’t feel I have enough brakes or capacity on my axles.
Can I easily upgrade?
A: Usually depending on the trailer configuration, you can
upgrade your running gear to a higher capacity rating. We
recommend consulting with the trailer manufacturer first
before doing so.
Q: Can I change my brakes from electric to hydraulic or vice
versa?
A: This can be done on most axle models. We recommend
contacting the trailer manufacturer prior to changing your
braking system to identify any potential problems.
Introduction
-8-
Electric Brakes
The electric brakes on your trailer are similar to the drum brakes
on your automobile. The basic difference is that your automotive
brakes are actuated by hydraulic pressure while your electric
trailer brakes are actuated by an electromagnet. With all of the
brake components connected into the system, the brake should
operate as follows (see electric brake assembly illustration):
When the electrical current is fed into the system by the controller,
it flows through the electromagnets in the brakes. The high
capacity electromagnets are energized and are attracted to the
rotating armature surface of the drums which moves the actuating
levers in the direction that the drums are turning.
Braking Systems – Electric
Battery
Power Wire
Brake Wire
Ground Wire
Brake Controller Breakaway Switch
Stoplight Wire
-9-
The resulting force causes the actuating cam block at the shoe
end of the lever to push the primary shoe out against the inside
surface of the brake drum. The force generated by the primary
shoe acting through the adjuster link then moves the secondary
shoe out into contact with the brake drum.
Increasing the current flow to the electromagnet causes the
magnet to grip the armature surface of the brake drum more firmly.
This results in increasing the pressure against the shoes and
brake drums until the desired stop is accomplished.
Braking Systems – Electric
Towing Vehicle
Trailer Connection
12V Battery for
Breakaway Switch
-10-
Braking Systems – Electric
Features
Electrically actuated brakes have several advantages over other
brake actuation systems.
1. They can be manually adjusted at the controller to provide
the correct braking capability for varying road and load
conditions.
2. They can be modulated to provide more or less braking
force, thus easing the brake load on the towing vehicle.
3. They have very little lag time from the moment the tow
vehicle’s brakes are actuated until the trailer brakes are
actuated.
4. In an emergency situation, they can provide some braking
independent of the tow vehicle.
Left Hand or Road Side Brake Shown
Retractor Spring
Primary Shoe
Actuating
Lever
Backing Plate
Adjuster Spring
(hidden)
Adjuster Assembly Adjuster Lever
Magnet
Centering
Springs (2)
Self-Adjusting
Cable
Secondary Shoe
Note: Actuating lever should always wrap around front side
of axle, magnet wires should exit brake backing plate on
rear side of axle.
-11-
Braking Systems – Electric
Self Adjusting Feature (12¼” Brake Series Only)
Forward self adjust electric brakes were introduced in October
of 1996. This feature adjusts the brakes on both forward and
reverse stops. Brake adjustment occurs when lining wear results in
enough gap between the shoes and the brake drum surface. This
added clearance will allow the adjuster mechanism to rotate the
screw assembly at the bottom of the brake. That action expands
the distance between the shoes and thus closes the gap to the
drum surface.
Brake Controllers
Electric brake controllers provide power to the magnets to
actuate the trailer brakes. Dexter offers a state-of-the-art inertial
controller called the Predator DX2®. This controller features an
accelerometer design which senses the deceleration of the towing
vehicle and sends a proportional voltage to the electric trailer
brakes. Other features include a visual gain setting for quick and
easy adjustment and a digital LED display to show the voltage
output. A manual override sends full voltage to the trailer brakes,
regardless of gain setting, for emergency conditions and also
illuminates the brake lights to warn of an impending stop.
Most electric brake controllers provide a modulation function
that varies the current to the electric brakes with the pressure
on the brake pedal or amount of deceleration of the tow vehicle.
Electronic or timing controllers do not provide proportional
modulation. These controllers tend to be inexpensive but not the
best choice for optimum braking. It is important that your brake
controller provide approximately 2 volts to the braking system
when the brake pedal is first depressed and gradually increases
the voltage to 12 volts as brake pedal pressure is increased. If
the controller “jumps” immediately to a high voltage output, even
during a gradual stop, then the electric brakes will always be fully
energized and will result in harsh brakes and potential wheel
lockup.
-12-
Braking Systems – Electric
How to Use Your Electric Brakes Properly
Your trailer brakes are designed to work in synchronization with
your tow vehicle brakes. Never use your tow vehicle or trailer
brakes alone to stop the combined load.
Your brake controller must be set up according to the
manufacturer’s recommendations to ensure proper
synchronization between the tow vehicle and the trailer.
Additionally, you may have to make small adjustments
occasionally to accommodate changing loads and driving
conditions.
Proper synchronization of tow vehicle to trailer braking can only
be accomplished by road testing. Brake lockup, grabbiness,
or harshness is quite often due to the lack of synchronization
between the tow vehicle and the trailer being towed, too high of a
threshold voltage (over 2 volts), or under adjusted brakes.
Before any synchronization adjustments are made, your trailer
brakes should be burnished-in by applying the brakes 20-30
times with approximately a 20 m.p.h. decrease in speed, e.g. 40
m.p.h. to 20 m.p.h. Allow ample time for brakes to cool between
application. This allows the brake shoes and magnets to slightly
“wear-in” to the drum surfaces.
Trailer Wire Size Chart
Number
of Brakes
Hitch-to-Axle
Distance in Feet
Recommended
Minimum Hookup
Wire Size (Copper)
2 12 AWG
4 Under 30 12 AWG
4 30-50 10 AWG
6 Under 30 10 AWG
6 30-50 8 AWG
-13-
Braking Systems – Electric
Synchronizing Your Trailer Brakes
To ensure safe brake performance and synchronization, read the
brake controller manufacturer’s instructions completely before
attempting any synchronization procedure.
! CAUTION
Before road testing, make sure the area is clear of
vehicular and pedestrian traffic. Failure to brake safely
could result in an accident and personal injury to
yourself and/or others.
Make several hard stops from 20 m.p.h. on a dry paved road free
of sand and gravel. If the trailer brakes lock and slide, decrease
the gain setting on the controller. If they do not slide, slightly
increase the gain setting. Adjust the controller just to the point of
impending brake lockup and wheel skid.
Note: Not all trailer brakes are capable of wheel lockup. Loading
conditions, brake type, wheel and tire size can all affect whether
a brake can lock. It is not generally considered desirable to lock
up the brakes and slide the tires. This can cause unwanted flat
spotting of the tires and could also result in a loss of control.
If the controller is applying the trailer brakes before the tow vehicle
brakes, then the controller adjustments should be made so the
trailer brakes come on in synchronization with the tow vehicle
brakes. For proper braking performance, it is recommended that
the controller be adjusted to allow the trailer brakes to come
on just slightly ahead of the tow vehicle brakes. When proper
synchronization is achieved there will be no sensation of the trailer
“jerking” or “pushing” the tow vehicle during braking.
-14-
Braking Systems – Electric
General Maintenance – Electric Brakes
Brake Adjustment
Most Dexter 12¹⁄₄” electric brakes have a self adjusting feature. If
manual adjusting is required, use the following procedure:
Brakes should be adjusted (1) after the first 200 miles of operation
when the brake shoes and drums have “seated,” (2) at 3,000 mile
intervals, (3) or as use and performance requires. The brakes
should be adjusted in the following manner:
1. Jack up trailer and secure on adequate capacity jack stands.
Follow trailer manufacturer’s recommendations for lifting and
supporting the unit. Make sure the wheel and drum rotates
freely.
! CAUTION
Do not lift or support the trailer on any part of the
axle or suspension system. Never go under any trailer
unless it is properly supported on jack stands which
have been rated for the load. Improperly supported
vehicles can fall unexpectedly and cause serious injury.
2. If equipped, remove the adjusting hole cover from the
adjusting slot on the bottom of the brake backing plate.
3. With a screwdriver or standard adjusting tool, rotate the star
wheel of the adjuster assembly to expand the brake shoes.
Adjust the brake shoes out until the pressure of the linings
against the drum makes the wheel very difficult to turn.
4. Then rotate the star wheel in the opposite direction until the
wheel turns freely with a slight lining drag.
5. Replace the adjusting hole cover and lower the wheel to the
ground.
6. Repeat the above procedure on all brakes. For best results,
the brakes should all be set at the same clearance.
-15-
Braking Systems – Electric
Brake Cleaning and Inspection
Your trailer brakes must be inspected and serviced immediately if
a loss of performance is indicated. With normal use, servicing at
one year intervals is usually adequate. With increased usage, this
work should be done more frequently as required. Magnets and
shoes must be changed when they become excessively worn or
scored, a condition which can reduce vehicle braking.
Clean the backing plate, magnet arm, magnet, and brake shoes.
Make certain that all the parts removed are replaced in the same
brake and drum assembly. Inspect for any loose or worn parts,
stretched or deformed springs and replace as necessary.
! CAUTION
POTENTIAL ASBESTOS DUST HAZARD!
Some older brake linings may contain asbestos dust,
which has been linked to serious or fatal illnesses.
Certain precautions need to be taken when servicing
brakes:
1. Avoid creating or breathing dust.
2. Avoid machining, filing or grinding the brake linings.
3. Do not use compressed air or dry brushing for
cleaning (dust can be removed with a damp brush).
Brake Lubrication
Before reassembling, apply a light film of grease or anti-seize
compound on the brake anchor pin, the actuating arm bushing
and pin, and the areas on the backing plate that are in contact
with the brake shoes and magnet lever arm. Apply a light film of
grease on the actuating block mounted on the actuating arm.
CAUTION
Do not get grease or oil on the brake linings, drums or
magnets.
-16-
Magnets
Your electric brakes are equipped with high quality electromagnets
that are designed to provide the proper input force and friction
characteristics. Your magnets should be inspected and replaced if
worn unevenly or abnormally. As indicated below, a straightedge
should be used to check magnet condition. For best results, the
magnet should be flat.
Even if wear is normal as indicated by your straightedge, the
magnets should be replaced if any part of the magnet coil has
become visible through the friction material facing of the magnet.
It is also recommended that the drum armature surface be refaced
when replacing magnets (see section on Brake Drum Inspection).
Magnets should also be replaced in pairs – both sides of an axle.
Use only genuine Dexter replacement parts when replacing your
magnets.
NORMAL WEAR
Gaps show ABNORMAL
WEAR (replace magnet)
Straight Edge
Braking Systems – Electric
-17-
Braking Systems – Electric
Shoes and Linings
A simple visual inspection of your brake linings will tell if they
are usable. Replacement is necessary if the lining is worn to
¹⁄₁₆” or less. Shoes
contaminated with
grease or oil, or
abnormally scored
or gouged should
also be replaced.
Hairline heat cracks
are normal in bonded
linings and should not
be cause for concern.
When replacement
is necessary, it is
important to replace
both shoes on each brake and both brakes of the same axle. This
will help retain the “balance” of your brakes.
! CAUTION
POTENTIAL ASBESTOS DUST HAZARD!
Some older brake linings may contain asbestos dust,
which has been linked to serious or fatal illnesses.
Certain precautions need to be taken when servicing
brakes:
1. Avoid creating or breathing dust.
2. Avoid machining, filing or grinding the brake linings.
3. Do not use compressed air or dry brushing for
cleaning (dust can be removed with a damp brush).
After replacement of brake shoes and linings, the brakes must
be re-burnished to seat in the new components. This should be
done by applying the brakes 20 to 30 times from an initial speed
of 40 m.p.h., slowing the vehicle to 20 m.p.h. Allow ample time for
brakes to cool between applications. This procedure allows the
brake shoes to seat in to the drum surface.
Acceptable Hairline Cracks
-18-
Braking Systems – Electric
Introduction to Troubleshooting
Proper brake function is critical to the safe operation of any
vehicle. If problems are encountered with your trailer braking
system, the following guide can be used to find the causes and
remedies for some of the more common problems. If you are
unsure or unable to resolve the problem, please contact your
nearest repair facility for professional assistance.
Troubleshooting
Most electric brake malfunctions that cannot be corrected by either
brake adjustments or synchronization adjustments, can generally
be traced to electrical system failure. Voltmeters and ammeters
are essential tools for proper troubleshooting of electric brakes.
Mechanical causes are ordinarily obvious, i.e. bent or broken
parts, worn out linings or magnets, seized lever arms or shoes,
scored drums, loose parts, etc. Replace defective parts with
genuine Dexter replacements.
Please consult the following troubleshooting charts to determine
the causes and solutions for common problems found in trailer
braking systems.
! CAUTION
Best braking performance is achieved with a controller
setting that is just short of wheel lock up or slide. Overly
aggressive braking which results in wheel lock up and
sliding, can cause a dangerous loss of control and
result in personal injury or death.
-19-
Braking Systems – Electric
Troubleshooting
Open Circuits
Faulty Controller
Short Circuits
Grease or Oil on
Magnets or Linings
Worn Linings
or Magnets
Scored or Grooved
Brake Drums
Improper
Synchronization
Underadjustment
Improper
Synchronization
Severe
Underadjustment
Corroded Connections
Glazed Linings
Overloaded Trailer
Underadjustment
Faulty Controller
Loose, Bent or Broken
Brake Components
Out-of-Round
Brake Drums
Insufficient Wheel Load
Faulty Controller
Broken Wires
Loose Connections
Find & Correct
Adjust Brakes
Test & Correct
Clean or Replace
Clean & Correct
Cause of Corrosion
Replace
Machine or Replace
Correct
Adjust Brakes
Reburnish or Replace
Correct
Adjust
Correct
Test & Correct
Replace Components
Machine or Replace
Adjust System Resistor
and Synchronize
Test & Correct
Repair or Replace
Find & Repair
No Brakes
Weak Brakes
Locking Brakes
Intermittent Brakes
Find & Correct
SYMPTOM CAUSES REMEDIES
Faulty Ground Find & Repair
-20-
Troubleshooting
Incorrect Adjustment
Broken Wires
Bad Connections
Underadjustment
Improper Controller
Faulty Controller
Underadjustment
Lack of Lubrication
Out-of-Round or
Cracked Brake Drums
Grease or Oil on
Linings or Magnets
Improper
Synchronization
Broken
Brake Components
Incorrect Brake
Components
Grease or Oil on
Linings or Magnet
Faulty Controller
Overadjustment
Out-of-Round
Brake Drums
Incorrect Brake
Components
Loose, Bent or Broken
Brake Components
Faulty Breakaway
Switch
Loose Wheel
Bearing Adjustment
Adjust
Clean or Replace
Find & Repair
Find & Repair
Adjust
Correct
Change
Test & Correct
Adjust
Lubricate
Replace Component
Correct
Clean or Replace
Machine or Replace
Test & Correct
Readjust
Machine or Replace
Replace
Replace
Repair or Replace
Adjust
Bent Spindle Replace Axle
Harsh Brakes
Noisy Brake
Surging Brakes
Dragging Brakes
Brakes Pull to
One Side
SYMPTOM CAUSES REMEDIES
Wrong Magnet Correct
Lead Wire Color
Braking Systems – Electric
-21-
Braking Systems – Electric
How to Measure Voltage
System voltage is measured at the magnets by connecting the
voltmeter to the two magnet lead wires at any brake. This may be
accomplished by using a pin probe inserted through the insulation
of the wires. The engine of the towing vehicle should be running
when checking the voltage so that a low battery will not affect the
readings.
Voltage in the system
should begin at 0 volts
and, as the controller
bar is slowly actuated,
should gradually increase
to about 12 volts. If
the controller does not
produce this voltage
control, consult your
controller manual.
The threshold voltage of a
controller is the voltage applied to the brakes when the controller
first turns on. Lower threshold voltage will provide for smoother
braking. If the threshold voltage is too high, the brakes may feel
grabby and harsh.
How to Measure Amperage
System amperage is the current flowing in the system when all the
magnets are energized. The amperage will vary in proportion to
the voltage. The engine of the tow vehicle should be running with
the trailer connected when checking the trailer braking system.
One place to measure system amperage is at the BLUE wire of
the controller, which is the output to the brakes. The BLUE wire
must be disconnected and the ammeter put in series into the line.
System amperage draw should be as noted in the following table.
Make sure your ammeter has sufficient capacity and note polarity
to prevent damaging your ammeter. With new ammeters that have
inductive pickup clamps, it is not necessary to cut the blue wire.
VOLTMETER
-22-
Magnet Amperes Chart
Brake
Size
Amps/
Magnet
Two
Brakes
Four
Brakes
Six
Brakes
12¹⁄₄” x 3³⁄₈”
4″, 5″
3.0 6.0 12.0 18.0
If a resistor is used in the brake system, it must be set at zero or
bypassed completely to obtain the maximum amperage reading.
Individual amperage draw can be measured by inserting the
ammeter in the line at the magnet you want to check. Disconnect
one of the magnet lead
wire connectors and
attach the ammeter
between the two wires.
Make sure that the wires
are properly reconnected
and sealed after testing is
completed.
The most common
electrical problem is
low or no voltage and
amperage at the brakes. Common causes of this condition are:
1. Poor electrical connections
2. Open circuits
3. Insufficient wire size
4. Broken wires
5. Blown fuses (fusing of brakes is not recommended)
6. Improperly functioning controllers or resistors
Another common electrical problem is shorted or partially shorted
circuits (indicated by abnormally high system amperage). Possible
causes are:
1. Shorted magnet coils
2. Defective controllers
3. Bare wires contacting a grounded object
Finding the cause of a short circuit in the system is done by
isolating one section at a time. If the high amperage reading drops
to zero by unplugging the trailer, then the short is in the trailer. If
Braking Systems – Electric
AMMETER
-23-
Braking Systems – Electric
the amperage reading remains high with all the brake magnets
disconnected, the short is in the trailer wiring.
All electrical troubleshooting procedures should start at
the controller. Most complaints regarding brake harshness
or malfunction are traceable to improperly adjusted or
non‑functioning controllers. See your controller manufacturer’s
data for proper adjustment and testing procedures. For best
results, all the connection points in the brake wiring should be
sealed to prevent corrosion. Loose or corroded connectors will
cause an increase in resistance which reduces the voltage
available for the brake magnets.
-24-
Braking Systems – Hydraulic
Hydraulic Brakes
The hydraulic brakes on your trailer are much like those on your
automobile or light truck. The hydraulic fluid from a master cylinder
or actuation system is used to actuate the wheel cylinder, which
in turn applies force against the brake shoes and drum. The main
difference between automotive hydraulic brakes and hydraulic
trailer brakes is the trailers’ actuation system. These systems
respond to the braking signal from the tow vehicle and supply the
required brake fluid volume and pressure to the trailer brakes.
CAUTION
The maximum operating pressure for Dexter 12¹⁄₄”
hydraulic brakes is 1,000 PSI.
-25-
Braking Systems – Hydraulic
Hydraulic Drum Brake Operation
Duo-Servo
The duo-servo brake uses a dual piston wheel cylinder to apply
the brakes. This type of brake is typically used in an electric/
hydraulic, vacuum/hydraulic, or air/hydraulic system. A description
of operation of this brake is as follows:
When the brakes are applied, the double-acting wheel cylinder
moves the primary
and secondary shoes
towards the drum. The
frictional force between
the brake drum and
lining attempts to turn
the primary shoe into
the secondary shoe.
The secondary shoe is
forced onto the anchor
pin and from this point,
the secondary and
primary shoes attempt
to “wrap around”. In essence, the brake has utilized frictional force
to help the applying force on both shoes.
If the brakes are applied while the vehicle is backing, the shoes
rotate in the direction of the drum rotation. This causes the
secondary shoe to leave the anchor and causes the primary shoe
to move against the anchor. Action of the brake is the same in
reverse as forward.
Anchor Post
Hydraulic Wheel
Cylinder
Actuating Pin
Primary Shoe
Adjuster Spring Adjuster Assembly
Secondary
Shoe
Retractor
Spring
Actuating Pin
-26-
Braking Systems – Hydraulic
Uni-Servo
This type of hydraulic brake utilizes a single acting cylinder. Upon
actuation, the primary
shoe is pressed
against the brake
drum, which causes
the shoe to move in the
direction of rotation.
This movement in turn
actuates the secondary
shoe through the
adjuster link assembly.
Braking in reverse
is significantly less
effective than in the
forward direction. Uni‑servo brakes are normally used with surge
type actuators.
Self Adjusting Mechanism
for 12¼” Hydraulic Brakes
Forward self-adjust hydraulic brakes were introduced in March,
1997. This feature adjusts the brakes on both forward and reverse
stops. Brake adjustment occurs only when lining wear results in
enough gap between the shoes and the drum surface. This added
clearance will allow the adjuster mechanism to rotate the screw
assembly at the bottom of the brake. That action expands the
distance between the shoes and thus closes the gap to the drum
surface.
Hydraulic Parking Brake Option
The parking feature on Dexter hydraulic brakes is cable operated.
The cable end is attached to the internal parking brake lever to
actuate the brake. On Dexter 12¹⁄₄” brakes manufactured before
February 2002, the parking cable body mounts to a support plate
which is attached to the brake mounting flange. The cable end is
routed through the dust shield and the brake spider to attach to
the internal parking brake lever. For 12¹⁄₄” brakes produced after
February 2002, a short cable is installed directly into the backing
plate to provide a convenient means for the trailer manufacturer to
attach an appropriate operating system.
Anchor Post
Hydraulic Wheel
Cylinder
Actuating Pin
Primary Shoe
Adjuster Assembly
Adjuster Spring
Secondary
Shoe
Retractor
Spring
-27-
Braking Systems – Hydraulic
The internal parking brake lever of Dexter 12¹⁄₄” brakes transfers
the applied cable force through a cam mechanism. The cam
mechanism generates a spreading force between the primary and
secondary shoes. The shoes move toward the drum until contact
is made. Friction generated between the drum and lining contact
surface results in parking brake capability.
Park Cable
Park Lever
-28-
Braking Systems – Hydraulic
Hydraulic Disc Brakes
Dexter manufactures two types of disc brakes, the floating caliper
and the fixed caliper brake. With both styles, the disc brake uses
friction pads astride a ventilated rotor which is attached to the
wheel hub. When the brake is actuated, the pads are pressed
against the sides of the rotor causing drag to slow the rotating
disc. This action converts the kinetic energy (motion) into heat.
The heat is dissipated rapidly by the ventilated disc.
The floating caliper brake uses
piston(s) situated on one side of the
brake rotor. Hydraulic fluid pressure
pushes against the piston(s) to apply
the inboard brake pad. As the inboard
pad exerts force against the rotating
rotor surface, the caliper moves
laterally towards the trailer frame and
in turn applies an equivalent force to
the outboard brake pad against the
rotor surface. As the lining material
wears, the caliper will automatically
maintain the proper lining to rotor
clearance. The floating caliper design
is used on Dexter 10,000 and 12,000
lb. axle models.
Disc brake effectiveness is the same going either in a forward or
reverse direction. All Dexter disc brakes should be actuated with a
braking system that is capable of providing a maximum hydraulic
pressure of 1,600 psi.
5/5/04:
All text & arrows taken out for
the 9-15K service manual
-29-
Braking Systems – Hydraulic
Electric/Hydraulic Actuation Systems
To effectively operate your hydraulic trailer brakes, we recommend
the Dexter E/H electro/hydraulic actuator, controlled by the
Predator DX2® electronic brake controller. These high performance
hydraulic power modules will supply pressurized brake fluid to
your trailer brakes in proportion to the amount of braking effort
called for by the towing vehicles’ deceleration rate.
CAUTION
It is the responsibility of the end user to ensure that
their in-cab electronic controller is compatible with
the Dexter E/H actuator. Dexter attempts to provide
compatibility with most controllers available, but is
unable to anticipate design changes that might be
introduced by the various controller manufacturers.
The E/H 1000 will supply 1,000 psi for your drum brakes and the
E/H 1600 will generate 1,600 psi for maximum output for your
Dexter disc brakes. The sealed, weather tight housing contains the
electronics necessary to control the high pressure piston pump
and proportioning valve for smooth, efficient braking.
Vacuum/Hydraulic
The basic actuation system consists of a vacuum booster,
synchronizing valve, check valve and a plumbing kit which
includes all lines and fittings. A vacuum supply from the engine
manifold is routed to the front of the booster and the top chamber
of the synchronizing valve through flexible hoses. The rear of
the booster and the lower chamber of the synchronizing valve
are connected by a separate line. The vacuum from the engine
must pass through a normally closed check valve. The check
valve keeps gas vapor out of the system and ensures that the
highest vacuum available will be kept in the system. With the
engine running and with no brake pedal pressure, a vacuum exists
throughout the system. The synchronizing valve is connected to
the master cylinder hydraulic supply. When the brake pedal is
applied, the hydraulic pressure in the synchronizing valve forces a
poppet to open which allows atmospheric air to enter the bottom
-30-
Braking Systems – Hydraulic
chamber of the valve. Since this part of the valve is connected
to the rear of the vacuum booster, the vacuum on this side of
the booster chamber is lost. The vacuum on the front side of the
booster chamber is maintained and this atmospheric/vacuum
pressure differential causes a piston to move in the booster’s slave
cylinder. This piston applies the hydraulic pressure to the brakes
through the connecting hydraulic line. When the pedal is released,
the poppet in the synchronizing valve is closed and by internal
passages, the air in the rear of the booster chamber is removed.
This restores a vacuum which is equal to the vacuum in the front
part of the booster chamber. The pressure balance allows the
slave cylinder piston to be pulled back to its original position and
the hydraulic pressure to the brakes is released.
Air/Hydraulic
Air/hydraulic braking systems are commonly used when the tow
vehicle has a diesel engine which does not develop manifold
vacuum. The air/hydraulic tow vehicle has an air compressor
mounted on the engine to supply compressed air for the braking
system and other needs required by the tow vehicle trailer
combination. This air is routed to a booster chamber attached to
the trailer master cylinder. The air pressure multiplies hydraulic
output pressure which then sends fluid to the wheel cylinders.
The air over hydraulic systems are often controlled by a series
of control valves and servos to ensure proper braking under all
conditions.
-31-
Braking Systems – Hydraulic
Introduction to Troubleshooting
Proper brake function is critical to the safe operation of any
vehicle. A properly installed vacuum/hydraulic, electric/hydraulic,
or air/hydraulic system should not require any special attention
with the exception of routine maintenance as defined by the
manufacturer. If problems occur, the entire tow vehicle/trailer
braking system should be analyzed by a qualified mechanic.
Typical problems in a hydraulic braking system are:
• Air or vacuum leaks
• Hydraulic system leaks
• Air in brake lines
• Water or other impurity in brake fluid
• Rusted or corroded master or wheel cylinders
• Actuation system malfunction
Please consult the following troubleshooting charts to determine
the causes and solutions for common problems found in trailer
braking systems.
-32-
Troubleshooting
Loose, Bent or Broken
Brake Components
Underadjustment
Out-of-Round Drums
Replace Components
Adjust
Machine or Replace
Locking Brakes
Incorrect Tire
Pressure
Restricted Brake
Lines or Hoses
Malfunctioning Cylinder
Assembly
Defective or Damaged
Shoe and Lining
Blocked Master
Cylinder
Parking Brake
Cable Frozen
Unmatched Tires
on Same Axle
One Side
Out-of-Adjustment
Improper Lining
Thickness or Location
Inflate Evenly on Both
Sides to Req. Pressures
Match Tires on Axle
Repair or Replace
Install New Shoe and
Lining-Complete Axle
Adjust
Replace Rubber Parts
Fill with DOT4 Fluid
Open with Compressed
Air or Replace Cylinder
Free Cable
and Lubricate
Install New Shoes
and Linings
Pulls to One Side
Improper Fluid
Dragging
Check for Stuck
or Sluggish Pistons
SYMPTOM CAUSES REMEDIES
Lack of Lubrication
Broken Brake
Components
Incorrect Brake
Components
Adjust
Lubricate
Replace Components
Correct
Underadjustment
Noisy Brakes
Braking Systems – Hydraulic
-33-
Troubleshooting
Broken or Kinked
Brake Line
Malfunctioning
Actuation System
Brake Adjustment
Not Correct
Excessively Worn
Brake Linings
Grease or Fluid
Soaked Lining
Glazed Lining
Excessive Drum Wear
Severe
Underadjustment
Incorrect Lining
Trapped Air in Lines
Overloaded Trailer
Repair or Replace
Adjust Brakes
Troubleshoot System
Replace Shoe
and Lining
Install Correct
Shoe and Lining
Repair Grease Seal or
Wheel Cylinder. Install
New Shoe and Lining.
Recondition or Replace
All Cylinders, Brake Fluid
Reburnish or Replace
Replace
Bleed System
Correct
No Brakes
Weak Brakes
Frozen Master Cylinder
or Wheel Cylinder Pistons
Manual-Adjust Brakes
Automatic-Make Several
Reverse Stops
SYMPTOM CAUSES REMEDIES
Malfunctioning
Actuating System
Troubleshoot
System
Grease or Fluid
on Linings
Replace Shoes
and Linings
Manual-Adjust Brakes
Automatic-Make Several
Reverse Stops
Harsh Brakes
Brake Adjustment
Not Correct
Machine or Replace
Surging Brakes
Grease or Oil
on Linings
Out of Round Drums or
Cracked Drums
Clean or Replace
Braking Systems – Hydraulic
-34-
Braking Systems – Hydraulic
Electric/Hydraulic Troubleshooting Guide
Trailer
Plug
From Tow
Vehicle Controller
(Typically Blue)
+12 Volt 40 Amp
Circuit From
Tow Vehicle
Ground From
Tow Vehicle
Break-
Away
Switch
Blue
Black
White
Minimum
9 Amp Hour
Breakaway
Battery
BLACK
WHITE
Lanyard
Connect
To The
Trailer
Ground
Circuit
Hydraulic
Line
Orange/Black
Light Blue/Yellow
White
Black
Blue
Charger
Electrical Schematic
Yellow
Note: Either an onboard or breakaway
battery may be used.
Brakes are slow to respond
1. Re-bleed the trailer brakes and actuator.
2. If the trailer is equipped with drum brakes, readjust the drum
brakes to the brake manufacture’s recommended running
clearance.
3. Slow response can be caused by trailer wiring that is too
small.
4. For trailers where the E/H unit is located less than 10 feet
from the tow vehicle, 12 gage wire is recommended for the
black and white wires between the tow vehicle and the E/H
unit. All other wires should be a minimum of 16 gauge.
5. For trailers where the E/H unit is located more than 10 feet
from the tow vehicle, 10 gage wire is recommended for the
black and white wires between the tow vehicle and the E/H
unit. All other wires should be a minimum of 16 gauge.
6. Slow response can be caused by improper adjustment
of the brake controller. On inertia-based electronic brake
controls, adjust the pendulum (inertia sensor) to a more
aggressive setting and/or increase the gain setting.
-35-
Braking Systems – Hydraulic
Unit will not run when the ignition is on and the brake pedal
is depressed
1. Verify that the trailer and tow vehicle are wired as detailed
on the electrical schematic.
2. With the ignition switch on and the brakes not applied, you
should have 12-13 volts between the black and white wires
on the E/H unit.
3. Clean and replace the ground between the trailer and the
E/H unit.
4. Test operation of the unit using the breakaway test
procedure.
Breakaway test procedure – do not leave the breakaway
switch pulled for more than two minutes during any of the
steps outlined below
1. Pull the breakaway switch on the trailer.
2. If the unit runs and builds pressure, that indicates the
actuator is functioning properly. The problem most likely is
a defective electronic brake controller in the tow vehicle or
defective wiring between the tow vehicle and the E/H unit.
3. If the unit runs but will not build pressure, the problem most
likely is a defective solenoid valve in the E/H unit and the
actuator should be returned for repair.
4. If the unit still does not run after the breakaway battery is
fully charged, verify that the voltage between the white wire
and yellow wire is at least 12 volts.
5. If the voltage is less than 12 volts, either the breakaway
switch or the breakaway wiring is defective.
6. If the voltage is greater than 12 volts, the E/H unit should be
returned for repair.
Trailer brakes too aggressive
1. Reduce the gain setting on the in-cab electronic brake
controller.
-36-
Braking Systems – Hydraulic
General Maintenance ‑ Hydraulic Brakes
Drum Brake Adjustment
Most Dexter 12¹⁄₄” hydraulic brakes have a self adjusting feature. If
manual adjusting is required, use the following procedure:
Brakes should be adjusted (1) after the first 200 miles of operation
when the brake shoes and drums have “seated,” (2) at 3,000 mile
intervals, (3) or as use and performance requires. The brakes
should be adjusted in the following manner:
1. Jack up trailer and secure on adequate capacity jack stands.
Follow trailer manufacturer’s recommendations for lifting and
supporting the unit. Make sure the wheel and drum rotates
freely.
! CAUTION
Do not lift or support the trailer on any part of the axle
or suspension system. Never go under any trailer unless
it is properly supported on jack stands which have been
rated for the load. Improperly supported vehicles can
fall unexpectedly and cause serious injury or death.
2. Remove the adjusting hole cover from the adjusting slot on
the bottom of the brake backing plate.
3. With a screwdriver or standard adjusting tool, rotate the star
wheel of the adjuster assembly to expand the brake shoes.
Adjust the brake shoes out until the pressure of the linings
against the drum makes the wheel very difficult to turn.
4. Then rotate the star wheel in the opposite direction until the
wheel turns freely with a slight lining drag.
5. Replace the adjusting hole cover and lower the wheel to the
ground.
6. Repeat the above procedure on all brakes. For best results,
the brakes should all be set at the same clearance.
-37-
Braking Systems – Hydraulic
Most of the brake components are very similar to those used in
electric brakes, and maintenance is comparable for the hub and
drum, shoes and linings, and bearings. Specific maintenance
activities are as follows:
Wheel Cylinders
Inspect for leaks and smooth operation. Clean with brake cleaner
and flush with fresh brake fluid. Hone or replace as necessary.
Brake Lines
Check for cracks, kinks, or blockage. Flush with fresh brake fluid.
Bleed system to remove all air. Use DOT3 or DOT4 brake fluid,
and replace as necessary.
Shoes and Linings
A simple visual inspection of your brake linings will tell if they are
usable. Replacement is necessary if the lining is worn (to within
¹⁄₁₆” or less), contaminated with grease or oil, or abnormally scored
or gouged. Hairline heat cracks are normal in bonded linings and
should not be cause for concern. When replacement is necessary,
it is important to replace both shoes on each brake and both
brakes of the same axle. This will help retain the “balance” of your
brakes.
! CAUTION
POTENTIAL ASBESTOS DUST HAZARD!
Some older brake linings may contain asbestos dust,
which has been linked to serious or fatal illnesses.
Certain precautions need to be taken when servicing
brakes:
1. Avoid creating or breathing dust.
2. Avoid machining, filing or grinding the brake linings.
3. Do not use compressed air or dry brushing for
cleaning (dust can be removed with a damp brush).
-38-
After replacement of brake shoes and linings, the brakes must
be re-burnished to seat in the new components. This should be
done by applying the brakes 20 to 30 times from an initial speed
of 40 m.p.h., slowing the vehicle to 20 m.p.h. Allow ample time for
brakes to cool between applications. This procedure allows the
brake shoes to seat in to the drum surface.
Hardware
Check all hardware. Check shoe return spring, hold down springs,
and adjuster springs for stretch or wear. Replace as required.
Service kits are available.
Instructions for 10-12K
Hydraulic Disc Brakes
Notice to Buyer
It is recommended that all brakes be replaced at the same time to
ensure balanced braking performance.
Preparation
1. Jack up trailer and secure on adequate capacity jack stands.
Follow trailer manufacturers recommendations for lifting and
supporting the unit.
! CAUTION
Do not lift or support the trailer on any part of the axle
or suspension system. Never go under any trailer unless
it is properly supported on jack stands which have been
rated for the load. Improperly supported vehicles can fall
unexpectedly and cause serious injury or death.
2. Remove the wheel from the hub, leaving the brake exposed.
Removal of Old Brake Caliper
1. With tire-wheel assembly(s) removed from hub and zero
pressure in hydraulic system, remove hex nuts from
slider bolts and withdraw bolts from brake assembly. Note
orientation of anti-rattle springs. Lift calipers from assembly
and secure to prevent damage to brake hose. Do not allow
caliper to hang from the hose. Remove anti-rattle springs
and brake pad. Braking Systems –
Hydraulic
-39-
Inspection
1. Slider bolts must be straight and free of rust pits, missing
chrome, or cracks in the chrome plating. Replace if
necessary. Anchor yoke bores must be free of corrosion and
excessive wear. O-Rings must be free from nicks and cuts.
Replace as necessary. Caliper assembly must be free of
fluid leaks and torn or deteriorated dust boots and O-Rings.
Repair as required.
2. Rotor-inspect for grooves, flaking, cracks, heat checking,
excessive thickness variation, insufficient overall rotor
thickness and overall width (measurement from inboard
rotor face to rotor mounting surface). Machine or replace as
necessary.
3. Rotor Specifications:
Rotor Thickness
10-12K
1.185 New, 1.12 Min. Service Limit
Rotor Thickness
#14 Torflex®
2.15 New, 2.09 Service Limit
Rotor Overall Width 3.655 New, 3.59 Service Limit
Lateral Runout .003 T.I.R., .010 T.I.R. Maximum
Thickness Variation .0008
Hub and Rotor Removal and Installation
1. With hubcap removed and oil drained, straighten locking
tabs on tang washer and remove outer locknut, tang washer,
inner locknut, bearing washer, and outer bearing. Remove
hub and rotor assembly.
Note: A puller may be required due to unitized seal press
fit on spindle. Remove inner bearing and seal. Service
bearings as necessary.
2. Prior to reassembly, ensure that the hub bearing housing
is clean. Reinstall inner bearing. Coat the O.D. of a new
seal with a bore sealant (Permatex or equivalent) prior to
installation.
3. Mount hub and rotor assembly on spindle and install outer
bearing, bearing washer, and inner bearing nut.
Braking Systems – Hydraulic
-40-
4. Tighten inner nut to 100 Ft. Lbs. while turning hub to seat
bearings.
5. Loosen nut to remove pre-load torque. Hand tighten nut,
then back off ¹⁄₈ turn minimum, ¹⁄₄ turn maximum.
6. Install tab washer and outer locknut. Torque locknut to
100‑175 Ft. Lbs. Ensure that the inner nut does not rotate.
Bend 2 tabs over flat on outer locknut to secure.
7. Install hub cap and add oil to hub. Capacity is 2.5 oz. of SAE
90W gear oil.
Installation
1. Installation is reverse of disassembly. Use appropriate tools
and methods to retract caliper pistons sufficiently to reinstall
caliper over the new pads. Caliper and anchor yoke O-Rings
should be lubricated with a light film of high temperature
brake lubricant prior to slider bolt installations. Slider bolts
should be installed from the outboard side of the caliper.
Ensure the anti-rattle springs are located properly.
2. Use extreme care when installing the slider bolts to prevent
damage to the O-Rings. Installation tool #071-182-00
threaded onto the slider bolts is recommended.
3. DO NOT FORCE OR HAMMER BOLTS IN. Secure slider
bolts with new locknut. Actuate brakes numerous times to
remove excess pad clearance prior to operation of vehicle.
Torque Specifications:
Slider Bolts Locknuts 15-25 Ft. Lbs.
Anchor Yoke Mounting Nuts 45-55 Ft. Lbs.
Bleeder Screw 9-12 Ft. Lbs.
Rotor Mounting Nuts 10K-12K 85-95 Ft. Lbs.
Rotor Mounting Bolts #14 Torflex® 90-110 Ft. Lbs.
Outer Spindle Nuts 100-175 Ft. Lbs.
Hub Cap 20-30 Ft. Lbs.
Wheel Mounting Nuts
(with clamp ring)
200 Ft. Lbs.
Braking Systems – Hydraulic
-41-
Braking Systems – Hydraulic
Hydraulic Disc Brake Parts
Item Description
Qty/
Brake 10K, 12K
1 Anchor Yoke Assembly 10K-12K
(includes 6 of item #6)
1 090-002-02
1 Anchor Yoke Assembly #14 Torflex®
(includes 6 of item #6)
1 090-011-02
2 Caliper Assembly
(includes items #6, 3, 9, 10)
1 089-002-02
3 Caliper Piston 2 054-066-00
12 Shoulder Screw ⁵⁄₈ x 5 2 007-186-00
13 Hex Screw ⁷⁄₁₆-20 x 1.75 7 007-116-00
14 Flange Nut 8 006-046-00
15 Hex Nut ⁷⁄₁₆-20 7 006-017-00
16 Rotor Mounting Stud 8 025-014-00
17 ABS Sensor (straight) 1 097-004-00
19 ABS Sensor Retaining Clip 1 097-002-00
20 ABS Tone Ring 1 024-203-00
Caliper Repair Kit contains: 1 K71-181-00
6
7
9
10
O-Ring
Bleeder Screw
Caliper Seal
Dust Boot
4
1
2
2
010-062-00
054-069-00
054-067-00
054-068-00
Disc Brake Replacement Pad Kit contains: 1 K71-180-00
4
5
6
8
11
not shown
Brake Pad
Anti-Rattle Spring
O-Ring
Hex Locknut
Installation Tool
Grease Packet
4
4
20
4
1
1
091-003-00
046-105-00
010-062-00
006-228-00
071-182-00
088-008-00
Recommend hose with banjo fitting.
⁷⁄₁₆-20 threaded hole for fitting.
1
15 13
14
16
11 12
4 5 6
9
10
2 3
7
8
6
6
6
6
6
17
19 20
-42-
S-Cam Air Brakes
Operation
Trailer air brakes are operated by the tractor air supply through
a series of relay and check valves. When braking is desired, the
air is supplied to the axle air chamber which applies a force that
is multiplied by the slack adjuster lever arm length. This force
is transmitted rotationally through the camshaft which, through
the geometry of the S-head, spreads the brake shoes to contact
the brake drum surface. The air brake systems are an effective,
very durable braking system for use in high mileage or extreme
operating conditions. They can be outfitted with ABS (anti-lock
brake systems), automatic slack adjusters and spring brakes to
comply with Federal Motor Vehicle Safety Standard Part 571.121.
Push Rod
Length@ Rest
Braking Systems – Air
-43-
Braking Systems – Air
Air Brake Components
Air Chambers
The air chambers convert the compressed air into a mechanical
force on the slack adjuster. The force on the slack adjuster
operates on the end of the lever and converts the chamber output
force to a torque on the S-cam. Federal and state regulations state
the maximum pushrod stroke length as an indication of brake
adjustment. This stroke is shown by the maximum stroke indicator
located on the air chamber pushrod. Maximum allowable stroke is
achieved when the indicator is fully extended from the air chamber
housing.
Note: Due to manufacturing tolerances, some brakes may not
meet the maximum stroke length in the “green” state and may
require several burnish stops to allow the brake shoes to conform
to the drum diameter.
Spring Brake
For parking and emergency braking purposes, a spring brake
chamber can be used in conjunction with the standard air
chamber. The spring brake contains an additional air diaphragm
and a very strong spring. When air is applied to the spring brake,
the spring is held in the off position by the air diaphragm. When
the air is exhausted, the spring provides the braking force to the
air chamber pushrod, thus actuating the brakes.
! CAUTION
Do not disassemble the spring brake! It contains a
compressed spring that may cause injury if removed.
The spring brake must be caged before servicing and
should only be performed by qualified personnel.
-44-
Slack Adjusters
The air brake slack adjusters perform two functions: (1) The slack
adjuster acts as a lever arm to convert the linear pushrod force
to rotational camshaft torque. The length of the slack adjuster
determines the amount of torque multiplication provided from the
pushrod. (2) Allows a simple external adjustment of the lining to
drum clearance to compensate for shoe lining wear.
There are two types of slack adjusters, manual and automatic:
Manual slack adjusters
The manual slack adjusters require manual adjustment to
compensate for the brake lining wear and the associated drum to
lining gap that results. Adjustment is usually performed by rotating
the hex adjusting nut on the slack adjuster body to set a lining to
drum clearance of about .020-.030″. See instructions for manual
slack adjustment procedure.
Automatic slack adjuster
The automatic slack adjuster (ASA) maintains an optimum
clearance between the brake lining and the drum by automatically
adjusting on the return stroke during brake application. Various
brands of ASA’s may work differently. The initial adjustment and
set-up of the ASA’s is critical to proper function of the air brake.
See instructions for slack adjuster procedure.
Note: Automatic slack adjusters are required on some commercial
trailers over 26,000 lbs., manufactured after 10/20/94 per FMVSS
Part 571.121. DO NOT REPLACE AUTOSLACKS WITH MANUAL
SLACK ADJUSTERS ON THESE TRAILERS.
S-Cams
The S-cams rotate from the torque applied by the slack adjusters,
resulting in spreading the brake shoes which applies the braking
force to the drum. The S-cams are supported by two nylon, grease
lubricated bushings. Due to the high forces exerted on the cam
bushings, periodic inspection, lubrication and maintenance is
required to achieve proper braking performance.
Braking Systems – Air
-45-
Braking Systems – Air
Brake Shoes
The air brake shoes are the final link in the braking system. The
brake shoes are supported by pins inserted into the brake spider,
and rollers that contact the S-cam surface. The shoes have a
replaceable lining riveted to them. The linings have two different
blocks, designated Cam and Anchor side. The brake shoes on
your Dexter axle are specifically designed for that axle. Only
Dexter authorized parts should be used for replacement since
there are small dimensional differences between air brake parts
suppliers that can significantly affect the function of the brake.
! CAUTION
Improperly fitted brake parts can cause brakes to
malfunction and cause loss of braking and/or wheel
lockup. Loss of braking can cause an accident resulting
in injuries or death.
16-1/2 x 7″ Q Style Brake Shoe
for 9-15K Service Manual (air brake section)
-46-
General Maintenance/Adjustment
Brake Component Lubrication
Camshaft bushings
Lubricate with approved grease through the grease fittings at the
spider and camshaft support bracket locations. Apply just enough
grease so grease is visible flowing past camshaft bushing seals.
During this process it is advisable to grab the camshaft and shake
the camshaft to see if there is excessive clearance in the camshaft
bushings due to wear.
Camshaft roller journals and brake anchor pins
These components are to be lubricated with a high temperature
anti-seize grease upon disassembly, maintenance and
reassembly.
Manual and automatic slack adjusters
Lubricate with Lithium base NLGI Grade 1 anti-wear grease
with rust and oxidizer additives applied at intervals of 3 to 6
months or 50,000 miles or per slack adjuster manufacturer’s
recommendations.
Anchor Pins
and Roller Journals
Lubricate with high
temperature anti-seize
grease
Spider and
Support Bushings
Lubricate with NLGI
Grade 2
For Manual Slack Adjusters
Lubricate with NLGI Grade 2
For Automatic Slack Adjusters
Lubricate with ASA manufacturers
recommended lubricant
Braking Systems – Air
-47-
Braking Systems – Air
12¹⁄₄” Quick Change Brakes – PQ
Recommended Disassembly
1. Block and secure trailer on adequate capacity jack stands.
Follow trailer manufacturers recommendations for lifting and
supporting the unit. Check that the wheel and drum rotate
freely.
2. Release brake and back off slack adjuster.
3. Remove wheel equipment.
4. Lift top shoe upward to disengage the shoe webs from the
anchor pin. Remove anchor pin.
5. Repeat procedure 4 for the bottom shoe.
6. Remove brake keeper springs.
7. Unwrap bottom shoe by pivoting the shoe on the camshaft
head and twisting the shoe 90° under the spindle. Remove
shoe assemblies from spider.
8. Remove slack adjuster lock ring, disconnect slack clevis,
and then remove slack adjuster.
9. Remove camshaft lock ring, spacer washer(s) and camshaft.
10. Completely inspect all brake components, servicing as
necessary.
Recommended Reassembly
1. Install new camshaft bushing. Ream bushing to 1.505/1.515
if required. Install camshaft seals into the spider.
Note: When installing camshaft seals, the seal on the slack
adjuster side is installed with seal facing into spider. This
allows grease to purge outside the brake assembly when
greasing the camshaft bushing. It also aids to avoid damage
of the seal lip when camshaft is installed.
2. Install new cam roller assemblies onto the brake shoes.
Note: The head of roller pin should face the camshaft “D”
washer once shoes are installed on spider.
-48-
Braking Systems – Air
3. Install “D” shaped camshaft washer onto the camshaft.
4. Install the camshaft into the spider. Install 005-075-00
washer and lock ring retainer on the camshaft before sliding
the camshaft through the camshaft support bracket.
5. Install the slack adjuster and 005-134-00 washer and
069‑078-00 lock ring retainer for 28 spline camshafts or
005-075-00 washer and 069-020-00 lock ring retainer for
10 spline camshafts.
6. Lubricate cam roller notches with anti-seize lubricant prior to
installing cam roller assemblies onto the brake shoes. Bend
roller retainer loop down so that retainer will be at same
level as the shoe table and will not interfere with the brake
drum during the life of the lining blocks.
7. Install “W” shaped retractor spring retainer pin into the 0.50″
diameter shoe web holes near the camshaft roller end of the
shoe.
8. Install retractor spring between shoes. Place top shoe onto
spider as in service. Pivot bottom shoe on the camshaft
head and twist the shoe 90° under the spindle, properly
placing shoe on the spider as in service.
9. Install two (2) keeper springs on the anchor end of the
shoes.
10. Lubricate anchor pin bores and shoe anchor pins with antiseize
lubricant.
11. Repeat procedure 10 for the bottom shoe.
12. Lift top shoe upwards to clear anchor pin hole. Install anchor
pin.
13. Connect slack adjuster to brake chamber pushrod.
Note: Always use new springs when servicing brakes.
Always use Dexter shoes when replacing shoes.
-49-
Braking Systems – Air
Air Brake Automatic Slack Adjustment
Mounting and adjustment procedure
If available, use installation template per manufacturer’s directions.
If template is not available, use the following procedure:
1. Install air chamber with proper push rod length.
2. Install the slack onto the camshaft.
3. Adjust the slack arm up to the point where the slack arm
starts to engage into the clevis slot.
4. Take the ¹⁄₂” diameter pivot pin, and place it into the clevis
slot. Hold in place (at this point, the pin is like a shim).
5. Continue adjusting the slack arm back against the pin.
6. When the slack arm touches the pin, the slack rotation will
stop. The camshaft will start to rotate as you keep adjusting
the slack with the wrench.
7. Continue adjusting with the wrench, which is now bringing
the shoes into closer contact with the drum.
8. As you continue to adjust, spin the drum by hand to get a
feel for the brake drag.
9. Adjust until the drum stops.
10. Adjust an additional ¹⁄₄ to ¹⁄₂ turn of the wrench.
11. Pull slack away by hand, from the pin.
12. Remove the pin from the clevis slot.
13. Align ¹⁄₂” holes.
14. Insert ¹⁄₂” pin.
15. Make sure the drum rotates one (1) full revolution. If it
did, proceed to step sixteen (16). If it did not rotate one
revolution, remove the air chamber and slack. Start over at
step one (1). Do not tighten the adjuster hex nut as tight as
previously done.
16. Insert the ¹⁄₄” pin.
17. Install and secure the cotter pins in the clevis and adjuster
pins.
-50-
Braking Systems – Air
! CAUTION
To ensure brakes meet Federal performance
requirements, Dexter recommends that only original
equipment premium grade linings be used. Failure to
use proper linings can result in poor braking and cause
accidents and injuries.
Air Brake Manual Slack Adjustment
1. Grease cam bracket and spider fittings.
2. Adjust the slack adjuster until the brake lining comes into
contact with the brake drum.
A. For green brakes, there should be a slight amount of
wheel drag at initial adjustment to compensate for any
lining irregularities such as high spots.
B. For burnished or broken-in brakes, back off the slack
adjuster to achieve .010″ clearance between the drum
and shoes.
3. Apply brakes using normal truck operating pressure
(80-90 psi).
Note: A “green brake” is an unground, unburnished, brake.
Normal manufacturing tolerances dictate that there is a
break-in period required after which the lining will seat into
the brake drum. During this break-in period, the user must
be aware that additional brake adjustment will be mandatory
to achieve optimum braking performance.
CAUTION
USE OF AIR PRESSURE IN EXCESS OF 130 PSI COULD
RESULT IN FAILURE OF THE AIR CHAMBER OR SPRING
BRAKE CHAMBER.
-51-
Braking Systems – Air
4. Check the amount of push rod travel at the clevis pin. The
stroke should be as follows:
Chamber Type Maximum Stroke
9 1¹⁄₂”
12 1¹⁄₂”
16 1¹⁄₂”
20 1³⁄₄”
24 1³⁄₄”
30 2″
5. With air pressure applied to brakes, check for lining to drum
contact. The contact should approach 100%. Use a .010″
feeler gage if in doubt. It should not fit between the lining
and drum during brake application.
6. Release air pressure from the brakes and confirm that all
brakes release to the normal relaxed position.
A. When properly adjusted, the angle between the push rod
and the slack adjuster should be approximately 90° +/- 5°
when the brakes are applied.
B. Proper maximum stroke should be achieved after
adjusting the autoslack. Reference the push rod stroke
length chart.
-52-
Braking Systems – Air
Introduction to Troubleshooting
Proper brake function is critical to the safe operation of any
vehicle. A properly installed air brake system should not require
any special attention with the exception of routine maintenance
as defined by the manufacturer. If problems occur, the entire tow
vehicle/trailer braking system should be analyzed by a qualified
mechanic.
To assure safe operation and maximum durability of parts such
as brake linings and tires, it is necessary to position and install
the axle properly. It is recommended that the axle assembly be
installed so that camshafts rotate in the same direction as the
wheels. Installation in which the camshaft rotation is opposite that
of wheel rotation could cause noisy brakes, chatter, and wheel
“hop”. With this thought in mind, the axle should be ordered with
placement of air chamber and slack adjuster assemblies that will
ensure the correct directional rotation of the camshafts when the
axle is installed.
It is the responsibility of the axle installer to adjust the brakes
properly. The recommended adjustment procedure is covered in
the section pertaining to brakes.
Please consult the following troubleshooting charts to determine
the causes and solutions for common problems found in trailer
braking systems.
-53-
Braking Systems – Air
Troubleshooting
Airtrbl.eps
9/19/95
Air System
Malfunction
Air Lines
Kinked or Broken
Slack Adjuster
Broken
Brakes Out of
Adjustment
Brakes Out of
Adjustment
Troubleshoot per
System Mfgr’s Directions
Adjust Brakes
Replace
Adjust
No Brakes
Weak Brakes
SYMPTOM CAUSES REMEDIES
Harsh Brakes
Air Chamber
Malfunction Replace
Repair or Replace
Excessive Drum Wear Replace Drums
Excessive Lining Wear Replace Linings
Oil Soaked Linings Replace Linings
Overloaded Trailers Use Proper Load
Air System Malfunction Troubleshoot per
System Mfgr’s Directions
Wrong Size
Air Chamber
Use Correct Size Air
Chamber for Application
Brake Adjustment
Not Correct
Adjust
Oil on Linings Replace Linings
Wrong Brake
Component
Use Only Approved
Dexter Components
Worn Anchor Pin
Bushings or
Camshaft Bushings
Replace Bushings
S-Cam Flipped Replace Linings
and Drum If Needed
-54-
Troubleshooting
Airtrbl.9/19/SYMPTOM CAUSES REMEDIES
Air System Malfunction
Sticky Valves, Dirt, etc.
Troubleshoot per
System Mfgr’s Directions
Brake Lock-Up
Wrong Size
Air Chamber
Use Correct Size
Air Chamber
Incorrect Slack
Adjuster Length
Use Correct Length
Slack Adjuster
Air System Timing
Malfunction
– Too Low Relay Valve
Crack Pressure
– Quick Release Valve
Malfunction
Troubleshoot
per
System Mfgr’s
Directions
S-Cam Flipped Due to
Brake Lining Wear
Replace Linings,
Adjust
Broken Return
Springs
Determine Cause of
Breakage and Replace
Grease or Oil
on Linings Replace Linings
Surging Brakes
Out of Round
or Cracked Drums
Turn or Replace
Drums
Linings Dragging Due to
Weak or Broken
Return Spring
Replace
Return Springs
Wrong Component in
Brake
Use Only Dexter
Approved COmponents
Bearing Adjustment Re-adjust
Improper Mounting of
Air Chamber and
Slack Adjuster
Mount per
Recommended
Procedure
Overheating Brakes
Camshaft or Shoes
Frozen
Replace Bushing
Cams Froze in
Park Position
Replace Camshaft
Bushings
Braking Systems – Air
-55-
Hubs/Drums/Bearings
Hubs/Drums/Bearings
Hub Removal
Whenever the hub equipment on your axle must be removed for
inspection or maintenance the following procedure should be
utilized.
1. Elevate and support the trailer unit per manufacturers’
instructions.
! CAUTION
Do not lift or support the trailer on any part of the axle
or suspension system. Never go under any trailer unless
it is properly supported on jack stands which have been
rated for the load. Improperly supported vehicles can
fall unexpectedly and cause serious injury or death.
2. Remove the wheel(s).
3. Remove the grease or oil cap by unscrewing it
counterclockwise while holding the hub stationary.
4. Bend the locking tang down from the outer spindle nut and
remove spindle nut.
5. Remove the tang washer and unscrew the inner spindle nut
(counterclockwise) and remove the spindle washer.
6. Remove the hub from the spindle, being careful not to allow
the outer bearing cone to fall out. The inner bearing cone
will be retained by the seal.
Note: A gear puller may be necessary to remove hub from
spindle.
Brake Drum Inspection
There are two areas of the brake drum that are subject to wear
and require periodic inspection. These areas are the drum surface
where the brake shoes make contact during stopping and the
armature surface where the magnet contacts (only in electric
brakes).
-56-
The drum surface should be inspected for excessive wear or
heavy scoring. If worn more than .020″ oversized, or the drum
has worn out of round by more than .015″, then the drum surface
should be re-machined. If scoring or other wear is greater than
.090″ on the diameter, the drum must be replaced. When turning
the drum surface, the maximum rebore diameter for a 12¹⁄₄” brake
drum is 12.340″.
For electric brakes only, the machined inner surface of the brake
drum that contacts the brake magnet is called the armature
surface. If the armature surface is scored or worn unevenly, it
should be refaced to a 120 micro inch finish by removing not
more than .030″ of material. To ensure proper contact between
the armature face and the magnet face, the magnets should
be replaced whenever the armature surface is refaced and the
armature surface should be refaced whenever the magnets are
replaced.
Note: It is important to protect the wheel bearing bores from
metallic chips and contamination which result from drum turning or
armature refacing operations. Make certain that the wheel bearing
cavities are clean and free of contamination before reinstalling
bearing and seals. The presence of these contaminants will cause
premature wheel bearing failure.
Bearing Inspection
Wash all grease and oil from the bearing cone using a suitable
solvent. Dry the bearing with a clean, lint-free cloth and inspect
each roller completely. If any pitting, spalling, or corrosion is
present, then the bearing must be replaced. The bearing cup
inside the hub must be inspected.
IMPORTANT: Bearings must always be replaced in sets of a cone
and a cup.
! CAUTION
Be sure to wear safety glasses when removing or
installing force fitted parts. Failure to comply may result
in serious eye injury.
Hubs/Drums/Bearings
-57-
Hubs/Drums/Bearings
When replacing the bearing cup proceed as follows:
1. Place the hub on a flat work surface with the cup to be
replaced on the bottom side.
2. Using a brass drift punch,
carefully tap around the
small diameter end of the
cup to drive out.
3. After cleaning the hub
bore area, replace the
cup by tapping in with
the brass drift punch. Be
sure the cup is seated all
the way up against the
retaining shoulder in the
hub.
Replace only with bearings as specified in the Bearing
Replacement Chart.
Bearing Lubrication – Grease
CAUTION
Do not mix Lithium, calcium, sodium or barium complex
greases due to possible compatibility problems.
When changing from one type of grease to another,
it is necessary to ensure all the old grease has been
removed.
Grease should be replaced every 12,000 miles or 12 months. Prior
to repacking bearings, all old grease should be removed from the
wheel hub cavity and bearings. Bearings should be packed by
machine if possible. If a machine is unavailable, packing by hand
method is acceptable. The method to pack bearing cones is as
follows:
1. Place a quantity of grease onto the palm of your hand.
-58-
2. Press a section of the widest end of bearing into the outer
edge of the grease pile closest to the thumb forcing grease
into the interior of the bearing
between two adjacent rollers.
3. Repeat this while rotating the
bearing from roller to roller.
4. Continue this process until you
have the entire bearing completely
filled with grease.
5. Before reinstalling, apply a light
coat of grease onto the bearing
cup mating surface.
Bearing Lubrication – Oil
If your axles are equipped with oil lubricated hubs, then your
lubrication procedure is to periodically fill the hub with a high
quality hypoid gear oil to the level indicated on the clear plastic oil
cap. The oil can be filled through the rubber plug hole in the cap.
Oil should be replaced every 12 months or 12,000 miles.
Hubs/Drums/Bearings
-59-
Hubs/Drums/Bearings
Recommended Wheel Bearing
Lubrication Specifications
Grease
Thickener Type Lithium Complex
Dropping Point 215°C (419°F) Minimum
Consistency NLGI No. 2
Additives EP, Corrosion & Oxidation Inhibitors
Viscosity Index 80 Minimum
Approved Grease Sources
Chem Arrow Arrow 2282
Chevron Texaco Chevron Ulti-Plex Grease EP #2
Texaco Starplex Moly MPGM #2
Citgo Lithoplex MP #2
Lithoplex CM #2
Mystik JT-6 Hi-Temp Grease #2
ConocoPhillips/
76 Lubricants/Kendall
Multiplex RED #2
L427 Super Blu Grease
Dexter Company Lithoplex Red MP #2
Exxon/Mobil Company Ronex, MP
Mobilith AW 2
Mobil I Synthetic Grease
Fuchs Renolit Uniwrl 2
Great Plains Lubricants Lithium Complex EP #2
Oil Center Research
of Oklahoma
Liquid-O-Ring No, 167L
Pennzoil-Quaker State
Company
Synthetic Red Grease
Royal Mfg. Company Royal 98 Lithium Complex EP #2
Shell Gadus S3 V220C
Gadus S5 V220
Rotella Heavy Duty Lithium
Complex #2
Valvoline Valvoline Multi-Purpose GM
Valvoline Durablend
-60-
Oil
SAE 90, SAE 80W-90, SAE 75W-90
Approved Oil Sources
Ashland Oil Valvoline Dura Blend
Valvoline Power Lube
CITGO Petroleum Co. CITGO Premium Gear Oil MP
Mystik JT-7
Mystik Power Lube
Conoco Universal Gear Lubricant 80W-90
Exxon Company USA Gear Oil GX 80W-90
Industrial Oils Unlimited Super MP Gear Oil 80W-90
Kendall Refining Co. Kendall NS-MP Hypoid Gear Lube
Lubriplate Division/
Fiske Brothers Refining
Lubriplate APG 90
MFA Oil Company Multi-Purpose Gear Oil 80W-90
Mobil Oil Corporation Mobilube SHC
Mobil 1 Synthetic Gear Lube
Phillips 66 Petroleum Superior Multi-Purpose Gear Oil
Philguard Gear Oil
Philsyn Gear Oil
Pennzoil Products Co. Gear Plus 80W-90 GL-5
Gear Plus Super 75W-90
Gear Plus Super EW 80W-90
Multi-Purpose 4092 Gear Lube
Oil Center Research Liquid-O-Ring 750 GX
Sun Refining and
Marketing Company
Sonoco Ultra
Sonoco Dura Gear
Shell Oil Company Spirax A
Spirax G
Spirax HD
Spirax S
Texaco Oil Company Multigear EP
Multigear SS
Troco Division/
Royal Manufacturing
Multigear Select Gear Oil
Union Oil Company Unocal MP Gear Lube
76 Triton Syn Lube EP Hubs/Drums/Bearings
-61-
Seal Inspection and Replacement
Whenever the hub is removed,
inspect the seal to assure that it
is not nicked or torn and is still
capable of properly sealing the
bearing cavity. If there is any
question of condition, replace the
seal. Use only the seals specified
in the Seal Replacement Chart.
To replace the seal:
1. Pry the seal out of the hub with a seal removal tool or a
screwdriver. Never drive the seal out with the inner bearing
as you may damage the bearing.
2. Apply a sealant similar to PERMATEX® High-Temp Red
RTV Silicone Gasket to the outside of the seal. Use only
enough to provide a thin coat to prevent any excess from
contaminating the rubber lip(s) of the seal. It is okay to apply
a slight amount of lube to the inner rubber lip(s) to aid with
installing onto the spindle.
Note: No sealant should be used if the outside of the seal is
rubber coated. For these type of seals it is recommended to
apply a thin coat of oil to the outside rubber.
3. Clean the seal journal of the spindle to inspect for nicks or
roughness. Use a file to remove any burrs from the leading
edge or shoulder area. Clean the journal area with very fine
emery cloth. Any presence of deep gouges or scratches in
this area may cause seal failure allowing lubricant to leak
out of the hub.
4, Clean the seal bore in the hub and inspect for any nicks,
gouges, or scratches that may prevent the seal from
retaining the bearing lubricant inside the hub.
5. Orient the seal properly. Many oil bath seals will be marked
AIR SIDE on the side of the seal to facing out of the hub
after installation.
6. Install new seal into place using a seal driver or seal
installation tool of proper size. It is important that any seal
Bad Seal: Nicks and Tears
(REPLACE SEAL)
Hubs/Drums/Bearings
-62-
installation tool contact the outer ring of the seal casing. If
no seal driver is available, use a clean block of wood. It is
critical that the seal be driven in evenly and straight. NEVER
hammer directly on the seal.
7. The seals will be pressed flush to the back surface of the
hub in the 9K-10K General Duty axle product line. The seals
in the 10K through 15K axles need to be installed so that
the airside face of the seal is approximately ¹¹⁄₁₆” from the
inner bearing cone. It is NEVER necessary to bottom out the
seal for proper installation. Driving the seal in too deep may
damage the seal and may come in contact with the inner
bearing preventing it from rotating freely.
8. Proper installation will maintain the seal flatness in the hub
within .010”. A seal that is cocked too much inside the hub
will be more likely to leak.
Installation/Adjustment
For ABS installation:
1. Assure that the ABS sensor is pushed fully into its retainer
clip (sensor tip is as far outboard as possible).
2. Install hub and drum squarely to the spindle centerline so
that the exciter ring inside the drum will contact the sensor
tip and push it back to the proper sensor to exciter ring
running clearance (gap should not exceed ¹⁄₁₆” inch).
For non-ABS installation, begin with step 3:
3. Install the bearing and washer into the hub. Thread on the
inner nut, rotate the hub and tighten the nut to 100 Ft. Lbs.
of torque.
4. Loosen the nut to remove preload torque, do not rotate hub.
5. Hand tighten the nut, then back it off ¼ to ³⁄₈ turn.
6. Place the tang washer on the spindle and bend two tangs
inward over the nut. This will keep the inner nut from turning
while torque is applied to the outer nut.
7. Install the outer nut and torque it to 100-175 Ft. Lbs. Ensure
that the inner nut does not turn. Bend two tangs from the
tang washer over the outer nut flats to secure.
Hubs/Drums/Bearings
-63-
Hubs/Drums/Bearings
8. Install cap with the O-ring and plug installed. Rotate the hub
and check the bearing adjustment. The allowable end play is
.001″-.010″.
! CAUTION
FAILURE TO BACK OFF THE INNER ADJUSTING
NUT COULD CAUSE BEARING AND AXLE SPINDLE
OVERHEATING OR DAMAGE, WHICH COULD RESULT
IN THE WHEEL LOCKING UP OR COMING OFF DURING
VEHICLE OPERATION AND LEAD TO AN ACCIDENT,
INJURIES OR DEATH.
! CAUTION
FAILURE TO TORQUE THE OUTER LOCKNUT
PROPERLY COULD CAUSE THE WHEEL END TO COME
OFF DURING VEHICLE OPERATION WHICH COULD
RESULT IN AN ACCIDENT, INJURIES OR DEATH.
-64-
Axle & Suspension Installation
Responsibility for proper axle alignment lies with the axle installer.
The axle must be installed so that it will be parallel to the drive
axle(s) of the tractor. This will allow good vehicle control when
cornering, longer tire wear, and it will eliminate dog tracking.
Alignment can be determined by measuring from the center of
the trailer king pin to the center of each end of the axles. The
difference should not vary by more than ¹⁄₁₆”. In the case of
multiple axles, the axles must also be in line with each other. The
difference between the centers of one axle and end centers of the
other axle must not vary more than ¹⁄₈”.
! CAUTION
Safety glasses should be worn at all times when
assembling or disassembling axles and their
components.
Dexter tubular axles are made of high strength steel for better
fatigue life and superior welding qualities. The round tubular axles
provide a uniform section modulus no matter how the beam is
rotated.
Brake spiders are positioned and welded to specific requirements
at our factory. Welding the spider directly to the axle beam
provides a higher strength and more reliable brake attachment
over bolt-on versions.
In welding suspension components to a Dexter trailer axle,
extreme care must be exercised to obtain correct location and
ensure the spring seat load bearing surfaces are parallel to each
other. Any welding of additional attachments to the axle should be
approved by Dexter’s engineering department.
Axle Installation
-65-
Suspensions
Suspension Systems
The suspension systems incorporated into Dexter axles are
designed to provide the trailer owner three basic functions:
1. Attach the axle to the trailer
2. Dampen the effects of road shock
3. Provide stability to the trailer
All Dexter suspension systems are available in single and multiple
axle configurations.
Slipper Leaf Springs
Slipper springs have an eye formed in one end only, with the other
end formed into a reverse curve. The attachment of these springs
is as follows:
1. The front eye is attached directly into the front hanger with a
bolt and nut.
2. The rear end of the spring is captured in the rear hanger or
equalizer with a “keeper bolt” that prevents the spring from
coming out when the trailer is jacked up for service.
U-Bolt
Tie Plate
Center
Hanger
Equalizer
U-Bolt
Tie Plate
Rear
Hanger
Front
Hanger
Spring Eye
Bolts
Spring Eye
Bolts
The articulation of this suspension occurs when the rear end of
each slipper spring slides against the wear surfaces provided in
the rear hangers or equalizers. This suspension is also available in
single and multiple axle configurations.
-66-
Suspensions
Inspection and Replacement
All the components of your suspension system should be visually
inspected least every 6,000 miles for signs of excess wear,
elongation of bolt holes, and loosening of fasteners. Whenever
loose or replaced, the fasteners in your suspension system
should be torqued as detailed in the charts at the end of this book
(Fastener Torque Values).
Worn spring eye bushings, sagging springs, or broken springs
should be replaced using the following method.
! CAUTION
Do not lift or support the trailer on any part of the axle
or suspension system. Never go under any trailer unless
it is properly supported on jack stands which have been
rated for the load. Improperly supported vehicles can
fall unexpectedly and cause serious injury or death.
1. Support the trailer with the wheels just off the ground. Follow
the trailer manufacturer’s recommendations for lifting and
supporting the unit. Do not lift or place supports on any part
of the suspension system.
2. After the unit is properly supported, place a suitable block
under the axle tube near the end to be repaired. This block
is to support the weight of the axle only so that suspension
COMPONENTS can be removed.
3. Disassemble the U-bolts, nuts, and tie plates.
4. Remove the spring eye bolts and remove the spring and
place on a suitable work surface.
5. If the spring eye bushings are to be replaced, press out the
old bushing using a hydraulic shop press.
-67-
Suspensions
! CAUTION
Be sure to wear safety glasses when removing or
installing force fitted parts. Failure to comply may result
in serious injury.
6. Lubricate the rubber bushing with liquid soap (not
petroleum.) Press the new bushing into the spring eye using
a hydraulic press.
7. Reinstall repaired or replaced components in reverse order.
Note: For multiple axle units, the weight of each axle must
be supported as outlined in Step 2 before disassembly of
any component of the suspension system.
If the equalizer or equalizer bushings must be replaced, follow
the instructions above for lifting and supporting the trailer unit and
then proceed as follows:
1. With both axles blocked up, remove the spring eyebolt,
keeper bolt, and equalizer bolt from the equalizer to be
repaired or replaced.
2. Press the old rubber bushing out of the equalizer using a
hydraulic press.
3. Lubricate the replacement bushing with liquid soap and
press into the equalizer.
4. Reassemble in reverse order.
! CAUTION
Be sure to wear safety glasses when removing or
installing force fitted parts. Failure to comply may result
in serious injury.
-68-
Suspensions
Suspension Replacement
1. Make sure springs are on straight. Align spring eyes to front
hanger. Insert spring eye bolts but do not torque at this
point.
2. Assemble springs into equalizer.
3. After leveling equalizer to frame, torque equalizer nuts
to values specified in Fastener Torque Specifications
(Replacement Parts/Kits section).
4. Torque spring eye bolts to values specified in Fastener
Torque Specifications (Replacement Parts/Kits section)
for rubber bushed suspension. Torque bronze bushed
suspension to snug fit only.
Torflex® Suspension
The Torflex® suspension system is a torsion arm type suspension
which is completely self contained within the axle tube. It attaches
directly to the trailer frame
using brackets which are
an integral part of the axle
assembly. The Torflex®
axle provides improved
suspension characteristics
relative to leaf spring
axles, through the unique
arrangement of a steel
torsion bar surrounded by
four natural rubber cords
encased in the main structural member of the axle beam.
The spindle is attached to a lever, called the torsion arm, which
is fastened to the rubber encased bar. As load is applied, the bar
rotates causing a rolling/compressive resistance in the rubber
cords. This action provides the same functions as conventional
sprung axles with several operating advantages including
independent suspension.
Except for periodic inspection of the fasteners used to attach
the Torflex® axle to the vehicle frame, no other suspension
Torsion Arm
Torsion Bar
Mounting Bracket Axle Tube
Spindle
-69-
Suspensions
maintenance is required on Torflex® axles. They are, of course,
subject to the maintenance and inspection procedures regarding
brakes, hubs, bearings, seals, wheels, and tires, as outlined in this
manual.
CAUTION
DO NOT WELD ON THE TORFLEX® BEAM. It has rubber
cords inside and the heat generated by welding could
damage the cords.
-70-
Suspensions
Heavy Duty Suspension
System Axle Alignment
Alignment
For safe and efficient trailer operation, to prevent excessive tire
wear off-tracking and hard pulling, it is recommended that after a
short break-in period you have a qualified trailer mechanic check
the alignment.
To align a four (4) spring suspension, the track arms need to be
adjusted. There is one adjustable track arm (rod) on each axle;
typically on the road (left) side.
Loosen the clamp nuts at each end of the adjusting bolt so the
adjusting rod can rotate (see Figure 1). Align front axle with the
king pin or coupler and adjust rear axle parallel to the front axle.
Be sure to secure the clamps on the adjustable track arm after
alignment (see Figure 1).
Alignment Procedure (Figure 1)
Before taking axle alignment measurements, make sure the trailer
is unloaded and free the suspension of any binds by pushing the
trailer backwards and then pulling the trailer forward. While pulling
the trailer forward on a level floor, apply the brakes and release.
This will ensure that an adjustable undercarriage is in its rearmost
lock position. The trailer MUST be level from side to side as well
as from front to rear.
Note: Neither service nor parking brakes should be applied during
the measurement procedure.
Ensure the king pin or coupler is at the correct height. Use axle
end extenders (or remove outer wheels and any obstructions) to
achieve a straight line for measuring from king pin to the axle ends
or axle centers.
Proper tools for axle alignment inspection are:
• Spring loaded kingpin extender with level or plum-bob.
• Axle end extenders.
• 50 foot steel tape.
• Optional; adjustable tram.
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• A means to measure axle center to axle center.
• Optional; Extra adjustable track arm (rod) clamp bolts if
required.
Adjust Clamp Bolt / Nut
Tighten to 130-170 Ft. Lbs.
Adjustable Track
Arm (Rod)
Adjust Clamp Bolt / Nut
Tighten to 130-170 Ft. Lbs.
Figure 1
Measuring (Figure 2)
1. Lateral Centerline (E). Determine lateral centerline of trailer
body and axles by measuring distance E between trailer and
axle centerlines first, and correct so that distance E is ¹⁄₄” or
less for each axle.
2. Thrust Angle (A, B). Measure distances A (curbside) then
B (roadside) from the king pin or coupler to the front of the
axle extension or axle centers. These must be equal to
within 0.1 degree or ¹⁄₈” of each other (A = B ± ¹⁄₈”). Ensure
the lateral tension (pulling force) applied to the measuring
tape is the same for both A and B measurements. Use a
tensioning device scale or optical (laser) to ensure accuracy.
3. Scrub Angle (C, D). Measure distances C (curbside) then
D (roadside) between axles, measuring from front of axle
extension to front of axle extension, or axle center to center.
Adjust the rear axle so it aligns to the front axle. These also
must be equal to within ¹⁄₁₆” of each other (C = D ± ¹⁄₁₆”). This
measurement should be as close to zero as possible. The
smaller the offset, the lower the rolling resistance and the
better the fuel economy.
Suspensions
-72-
C
D
A
B
E
Figure 2
Adjusting
1. Loosen the adjustable track rod clamp bolts (Figure 1) and
turn the center rod to adjust as necessary per above.
2. After adjusting, tighten the adjustable track rod clamp nuts
(Figure 1) to proper torque. Recheck measurements and
readjust as needed.
Precautions
1. Always measure to the front axle ends for accurate
alignment.
2. Avoid measuring to rims, suspension brackets, hub cap,
vent holes, brake drums, etc. This can result in improper
alignment. For accurate measurements, use axle extenders.
3. Always align any succeeding axles with the front axle, not to
the kingpin or coupler.
Additional Suspension Maintenance Check
Track arms should be checked for clearance. If slack is found,
it should be repaired immediately since this indicates that there
is wear in the rubber bushing or track arm parts. Check the
adjustable track arm clamps for proper torque. Loose clamps will
Suspensions
-73-
Suspensions
cause wear on the adjusting threads and the suspension cannot
be kept in alignment. On leaf spring type suspensions, have the
trailer checked for axle alignment after two to three thousand
miles.
Check leaf springs for broken leaves. Replace broken leaves
immediately to prevent the other leaves from being overloaded.
On taper leaf springs, be sure the plastic liner is serviceable and
on top of the spring. The liners between leaves should be in place
and serviceable.
Heavy Duty Suspension Torque Requirements
CAUTION
Before torquing equalizer bolts, level equalizers parallel
to main frame members. After initial break-in period (up
to 1,000 miles) and at least every 4 months thereafter;
all bolts and nuts should be checked to ensure
recommended torque is being maintained.
Minimum Torque Values for Bolts With
Clean Dry Threads
Description
Torque Min
Ft. Lbs.
Torque Max
Ft. Lbs.
1¹⁄₈-7 UNC Nut
Oiled
Dry
565
765
615
815
1-8 UNC Nut 325 350
Spring Keeper Nut
⁵⁄₈-18 UNF 35 50
Track Rod Clamp Nut
⁵⁄₈-18 UNF 130 170
-74-
Wheels
Wheel Selection
Wheels are a very important and critical component of your
running gear system. When specifying or replacing your trailer
wheels it is important that the wheels, tires, and axle are properly
matched. The following characteristics are extremely important
and should be thoroughly checked when replacement wheels are
considered.
1. Bolt Circle. Many bolt circle dimensions are available and
some vary by so little that it might be possible to attach an
improper wheel that does not match the axle hub. Be sure to
match your wheel to the axle hub.
2. Capacity. Make sure that the wheels have enough
load carrying capacity and pressure rating to match the
maximum load of the tire and trailer.
3. Offset. This refers to the relationship of the center line of
the tire to the hub face of the axle. Care should be taken to
match any replacement wheel with the same offset wheel
as originally equipped. Failure to match offset can result in
reducing the load carrying capacity of your axle.
4. Rim Contour.
! CAUTION
Replacement tires must meet the same specifications
as the originals. Mismatched tires and rims may come
apart with explosive force and cause personal injury to
yourself or others. Mismatched tires and rims can also
blow out and cause you to lose control and have an
accident which can result in serious injury or death.
Wheels and Tires
-75-
Wheels and Tires
! CAUTION
Do not attempt to repair or modify a wheel. Even minor
modifications can have a great effect. Do not install
a tube to correct a leak through the rim. If the rim is
cracked, the air pressure in the tube may cause the
pieces of the rim to explode with great force and can
cause serious injury or death.
Torque Requirements
It is extremely important to apply and maintain proper wheel
mounting torque on your trailer axle. Torque is a measure of
the amount of tightening applied to a fastener (nut or bolt) and
is expressed as length times force. For example, a force of 90
pounds applied at the end of a wrench one foot long will yield
90 Ft. Lbs. of torque. Torque wrenches are the best method to
assure the proper amount of torque is being applied to a fastener.
! CAUTION
Wheel nuts or bolts must be tightened and maintained
at the proper torque levels to prevent loose wheels,
broken studs, and possible dangerous separation of
wheels from your axle, which can lead to an accident,
personal injuries or death.
Be sure to use only the fasteners matched to the cone angle
of your wheel (usually 60° or 90°.) The proper procedure for
attaching your wheels is as follows:
1. Start all bolts or nuts by hand to prevent cross threading.
2. Tighten bolts or nuts in the following sequence.
3. The tightening of the fasteners should be done in stages.
Following the recommended sequence, tighten fasteners
per wheel torque requirements diagram.
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4. Wheel nuts/bolts should be torqued before first road use
and after each wheel removal. Check and re-torque after
the first 50 miles and again at 100 miles. Check periodically
thereafter.
Wheel Torque Sequence
Description Part No. Application
Torque
Min
Ft. Lbs.
Torque
Max
Ft. Lbs.
⁵⁄₈-18 90° Cone Nut 006-109-00 Clamp Ring
033-052-01
190 210
Greased
Threads
³⁄₄-10 Hex Nut 006-117-00 Demountable
Rim Clamp
210 260
³⁄₄-16 Spherical Nut 006-064-01, 02
006-069-01, 02
Single Wheel
Inner Dual
450
450
500
500
1¹⁄₈-16 Spherical Nut 006-070-01, 02 Outer Dual 450 500
⁵⁄₈-18 Non-Swiveling
Flange Nut
006-058-00 Wheels 275 325
⁵⁄₈-18 Swiveling
Flange Nut
006-209-00 Wheels 150 175
M22-1.5 006-118-00 Swivelling
Flange Nut
450 500
TORQUE SEQUENCE
8 BOLT
1
2
3 4
5
6
7
8
6 BOLT
1
2
3
5 4
6
1
2
3
5 4
7 9
6
10 8
10 BOLT
Wheels and Tires
-77-
Wheels and Tires
Tires
Before mounting tires onto wheels, make certain that the rim size
and contour is approved for the tire as shown in the Tire and Rim
Association Yearbook or the tire manufacturers catalog. Also make
sure the tire will carry the rated load. If the load is not equal on
all tires due to trailer weight distribution, use the tire rated for the
heaviest wheel position.
Use tire mounting procedures as outlined by the Rubber
Manufacturers Association or the tire manufacturers.
Tire inflation pressure is the most important factor in tire life.
Inflation pressure should be as recommended by the manufacturer
for the load. Pressure should be checked cold before operation.
Do not bleed air from tires when they are hot. Check inflation
pressure weekly during use to ensure the maximum tire life and
tread wear. The following tire wear diagnostic chart will help you
pinpoint the causes and solutions of tire wear problems.
! CAUTION
Proper matching of the tire/wheel combination is
essential to proper function of your trailer running gear.
Some tires may call for a maximum inflation pressure
above the rim or wheel capacity. DO NOT EXCEED
MAXIMUM INFLATION PRESSURES FOR RIMS OR
WHEELS. Catastrophic failure may result.
-78-
Tire Wear Diagnostic Chart
Center Wear
Edge Wear
Side Wear
Toe Wear
Cupping
Flat Spots
Over Inflation
Under Inflation
Loss of camber
or overloading
Incorrect toe-in
Out-of-balance
Wheel lockup &
tire skidding
Adjust pressure to
particular load per
tire catalog
Adjust pressure to
particular load per
tire catalog
Make sure load doesn’t
exceed axle rating.
Align at alignment shop.
Align at alignment shop.
Check bearing adjustment
and balance tires.
Avoid sudden stops
when possible and
adjust brakes.
Wear Pattern Cause Action
CAUTION
Tire wear should be checked frequently. Once a wear
pattern becomes firmly established in a tire it is difficult
to stop, even if the underlying cause is corrected.
Wheels and Tires
-79-
Replacement Parts/Kits
Replacement Parts/Kits
Fastener Torque Specifications
Description Application Part No.
Min
Torque
Ft. Lbs.
Max
Torque
Ft. Lbs.
Spindle Nut
Inner
Outer
9-15K
9-15K
See Bearing Installation/Adjustment
Grease Zerk Cam Bushing
Spider
5
8
15
8
Cam Brackets 3 4
Air Chamber 12-15K Air Brake 50 55
³⁄₈-16 Self Locking
Hex Nut
Shoe Hold Down 006-086-00 35 38
⁵⁄₈-11 Hex Locknut 9K, 10K, U-Bolt 006-038-00 110 150
¹⁄₂-13 Hex Head
Cap Screw
Drum Mounting
10-15K
007-244-00 90 110
¹⁄₂-13 Hex Cap
Screw
Drum Mounting
10K GD
007-245-00 90 110
⁵⁄₈-11 Hex Locknut 9K Spring Eye 006-038-00 130 150
1-8 Hex Locknut 9K Equalizer 006-112-00 325 375
1-8 Hex Locknut 10K GD Equalizer 006-112-00 325 375
³⁄₄-10 Hex Locknut 10K GD Spring Eye 006-113-00 200 250
³⁄₄-10 Hex Locknut 12K, 15K U-Bolt 006-113-00 160 200
1-8 Hex Locknut 10K, 12-15K
Spring Eye
Rubber Bushed
006-278-00 325 350
1¹⁄₈-7 Hex Locknut 10K, 12-15K
Equalizer Rubber
Bushed
006-072-00 350 400
Plastic Oil Cap Oil Hubs 021-035-00
021-036-00
021-088-00
20 30
⁷⁄₁₆-20 Hex Nut Brake Mounting 006-017-00 55 80
-80-
Bearing Replacement Chart
Inner Bearing Outer Bearing
Axle Dx. No. Industry No. Dx. No. Industry No.
9K, 10K GD 031-019-01
031-019-02
382A
387A
031-030-11
031-030-12
25520
25580
10K HD 031-022-01
031-022-02
394A
395S
031-019-01
031-019-02
382A
387A
12K 031-020-01
031-020-02
3920
3984
031-021-01
031-021-02
28622
28682
15K 031-020-01
031-020-02
3920
3984
031-021-01
031-021-02
28622
28682
Seal Replacement Reference
Axle Part Number Kit Number
9K 010-051-02 K71-387-00
10K GD 010-051-02 K71-387-00
10K HD 010-056-00 K71-388-00
12K 010-056-00 K71-388-00
15K 010-056-00 K71-388-00
Electric Brake Magnets
After June 2017
Brake Size
Magnet Kit Number
(one magnet per kit) Wire Color
12¹⁄₄” x 3³⁄₈” (9K, 10K GD)
4″ (10K HD)
5″ (12K & 15K)
K71-378-00 Red/Black
Prior to June 2017
Brake Size
Magnet Kit Number
(one magnet per kit) Wire Color
12¹⁄₄” x 3³⁄₈” 9K, 10K K71-376-00 Yellow
12¹⁄₄” x 4″ 10K K71-376-00 Yellow
12¹⁄₄” x 5″ 12K K71-377-00 Black
12¹⁄₄” x 5″ 15K K71-378-00 Blue
Replacement Parts/Kitsw
-81-
Replacement Parts/Kits
Brake Shoe Replacement Kits
Brake Size Description Shoe and Lining Replacement
12¹⁄₄” x 3³⁄₈” Electric Cast Back Plate
Electric Stamped Back Plate
Hydraulic
K71-499-00 LH; K71-498-00 RH
K71-049-00 LH; K71-050-00 RH
K71-165-00 LH; K71-166-00 RH
12¹⁄₄” x 4″ Electric Cast Back Plate
Electric Stamped Back Plate
Hydraulic
K71-501-00 LH; K71-500-00 RH
K71-051-00 LH; K71-052-00 RH
K71-167-00 LH; K71-168-00 RH
12¹⁄₄” x 5″ Electric Cast Back Plate
Electric Stamped Back Plate
Hydraulic
K71-503-00 LH; K71-502-00 RH
K71-053-00 LH; K71-054-00 RH
K71-169-00 LH; K71-170-00 RH
Air Brake Shoe & Linings
Axle Model Brake Size
Shoe & Lining No.
(2 Required per Brake)
10K HD 12¹⁄₄” x 4″ 040-321-01
12K, 15K 12¹⁄₄” x 5″ 040-322-01
Air Brake Repair Kits
Description Axle Model Kit Number
Camshaft PQ Style Repair Kit 10-15K K71-101-00
Brake Shoe PQ Style Hardware Kit 10-27K K71-460-00
Disc Brake Pad Kit
Axle Model Kit Number
10K or 12K K71-180-00
Disc Brake Caliper Repair Kit
Axle Model Kit Number
10K or 12K K71-181-00
-82-
Storage
Storage Preparation
If your trailer is to be stored for an extended period of time or over
the winter, it is important that the trailer be prepared properly.
1. Remove the emergency breakaway battery and store inside,
out of the weather. Charge the battery at least every 90
days.
2. Jack up the trailer and place jack stands under the trailer
frame so that the weight will be off the tires. Follow trailer
manufacturer’s guidelines to lift and support the unit. Never
jack up or place jack stands on the axle tube or on the
equalizers.
! CAUTION
Do not lift or support the trailer on any part of the axle
or suspension system. Never go under any trailer unless
it is properly supported on jack stands which have been
rated for the load. Improperly supported vehicles can
fall unexpectedly and cause serious injury or death.
3. Lubricate mechanical moving parts such as the hitch, and
suspension parts, that are exposed to the weather.
4. Boat trailer axles are subject to repeated immersion. Before
storing, remove brake drums; clean, dry and re-lubricate
moving brake components; inspect bearings – clean and
re‑lubricate.
5. On oil lubricated hubs, the upper part of the roller bearings
are not immersed in oil and are subject to potential
corrosion. For maximum bearing life, it is recommended
that you revolve your wheels periodically (every 2-3 weeks)
during periods of prolonged storage.
Storage
-83-
Storage
After Prolonged Storage
Inspection Procedure
Before removing trailer from jack stands:
1. Remove all wheels and hubs or brake drums. Note which
spindle and brake that the drum was removed from so that it
can be reinstalled in the same location.
2. Inspect suspension for wear.
3. Check tightness of hanger bolt, shackle bolt, and U-bolt nuts
per recommended torque values.
4. Check brake linings, brake drums and armature faces for
excessive wear or scoring.
5. Check brake magnets with an ohmmeter. The magnets
should check 3.2 ohms. If shorted or worn excessively, they
must be replaced.
6. Lubricate all brake moving parts using a high temperature
brake lubricant (LUBRIPLATE or Equivalent).
CAUTION
Do not get grease or oil on brake linings or magnet face.
7. Remove any rust from braking surface and armature surface
of drums with fine emery paper or crocus cloth. Protect
bearings from contamination while so doing.
8. Inspect oil or grease seals for wear or nicks. Replace if
necessary.
9. Lubricate hub bearings. Refer to procedure in manual.
10. Reinstall hubs and adjust bearings per instructions in
manual.
11. Mount and tighten wheels per instructions in manual.
-84-
Trip Preparation Checklist
There are a number of simple rules to follow in caring for your
trailer axle assembly that can add to its life and in the case of
some of these rules, you may be protecting your own life as well.
Using the following checklist before starting a trip with your trailer
is highly recommended. Some of these items should be checked
2-3 weeks prior to a planned trip to allow sufficient time to perform
maintenance.
1. Check your maintenance schedule and be sure you are
up‑to-date.
2. Check hitch. Is it showing wear? Is it properly lubricated?
3. Fasten safety chains and breakaway switch actuating
chain securely. Make certain the breakaway battery is fully
charged.
4. Inspect towing hookup for secure attachment.
5. Load your trailer so that approximately 10% of the trailer’s
total weight is on the hitch. For light trailers this should
be increased to 15%. Fifth wheel type trailer should have
15‑25% weight on the hitch.
6. Do Not Overload. Stay within your gross vehicle rated
capacity (consult your trailer’s identification plate).
7. Inflate tires according to manufacturer’s specifications;
inspect tires for cuts, excessive wear, etc.
8. Check wheel mounting nuts/bolts with a torque wrench.
Torque in proper sequence, to the levels specified in this
manual.
9. Make certain the brakes are synchronized and functioning
properly.
10. Check tightness of hanger bolt, shackle bolt, and U-bolt nuts
per torque values specified in manual.
11. Check operation of all lights.
12. Check that your trailer is towing in a level position and adjust
hitch height if required.
Storage
-85-
Warranty
Dexter Axle Limited Warranty
What Products Are Covered
All Dexter Axle Company (“Dexter”) trailer axles, suspensions,
and brake control systems manufactured on or after September 1,
2016, excluding Dexter 6000 series Manufactured Housing Axles.
Additional exclusions include the following brands: UFP by Dexter,
AL-KO (IAC), Titan Brakes and Actuators by Dexter, and BrakeRite
by Dexter products, which are covered under separate warranties.
Limited 1 Year Warranty
As specified in Dexter’s current publication “Operation
Maintenance Service Manual”, grease and oil seals FOR ALL
PRODUCTS have a one (1) year limited warranty to the original
purchaser from the date of first sale of the trailer incorporating
such components. Except as to grease and oil seals, the
following four other warranties are available.
Limited 2 Year Warranty
Dexter warrants to the original purchaser that its electric/hydraulic
brake actuators shall be free from defects in material and
workmanship for a period of two (2) years from the date of first
sale of the trailer incorporating such components.
Limited 5 Year Warranty
Dexter warrants to the original purchaser that its axles,
suspension systems and Genuine Replacement Parts shall be
free from defects in material and workmanship for a period of five
(5) years. The warranty period shall begin from the date of the
original purchase of the trailer and/or Genuine Replacement Parts.
Limited 7 Year Warranty
Dexter warrants to the original purchaser that its Predator Series®
electric brake controllers shall be free from defects in material
and workmanship for a period of seven (7) years from the date of
purchase.
Limited 10 Year Warranty
Dexter warrants to the original purchaser that the suspension
components of its Torflex® axles shall be free from defects in
material and workmanship for a period of ten (10) years from
the date of first sale of the trailer incorporating such suspension
components.
Exclusive Remedy
Dexter will, at its option, repair or replace the affected components
of any defective axle, repair or replace the entire defective
-86-
Warranty
axle, or refund the lesser of the original purchase price and the
then-current list price of the axle or components. In all cases, a
reasonable time period must be allowed for warranty repairs to
be completed. Allowance will only be made for installation costs
specifically approved by Dexter.
What You Must Do
In order to make a claim under these warranties:
1. You must be the original purchaser of the trailer in which the
sprung suspension axles or Torflex® axles or components were
originally installed.
2. You must promptly notify Dexter after detection of any defect,
but in any case within the applicable warranty period of such
defect, and provide us with the axle or applicable component
serial number and any substantiation of such defect which may
include, but is not limited to, the return of part(s) that we may
reasonable request.
3. The axles, suspensions and components must have been
installed and maintained in accordance with good industry
practice and any specific Dexter recommendations, including
those specified in Dexter’s current publication “Operation
Maintenance Service Manual”.
Exclusions
These warranties do not extend to and do not cover defects
caused by:
1. The connecting of brake wiring to the trailer wiring or trailer
wiring to the towing vehicle wiring.
2. The attachment of the running gear to the frame.
3. Parts not supplied by Dexter.
4. Any damage whatsoever caused by or related to any alteration
of the axle including welding supplemental brackets to the axle.
5. Use of an axle on a unit other than the unit to which it was
originally mounted.
6. Normal wear and tear.
7. Improper alignment.
8. Improper installation.
9. Unreasonable use (including failure to provide reasonable
and necessary maintenance as specified in Dexter’s current
publication “Operation Maintenance Service Manual including
required maintenance after “Prolonged Storage”).
-87-
Warranty
10. Improper torque values and torqueing of wheel nuts. (The
proper torqueing procedure and torque values are contained
in Dexter’s current publication “Operation Maintenance Service
Manual”).
11. Cosmetic finish or corrosion.
Limitations
1. In all cases, Dexter reserves the right to fully satisfy its
obligations under the Limited Warranties by refunding
the lesser of the original purchase price and the thencurrent
list price of the defective axle (or, if the axle has
been discontinued, of the most nearly comparable current
product).
2. Dexter reserves the right to furnish a substitute of replacement
component or product in the event an axle or any component
of the axle is discontinued or is otherwise unavailable.
3. These warranties are nontransferable.
General
THE FOREGOING WARRANTIES ARE EXCLUSIVE AND IN
LIEU OF ALL OTHER WARRANTIES EXCEPT THAT OF TITLE,
WHETHER WRITTEN, ORAL OR IMPLIED, IN FACT OR IN LAW
(INCLUDING ANY WARRANTY AGAINST INFRINGEMENT OR
OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR
PURPOSE).
These warranties give you specific legal rights, and you may also
have other rights which vary from state to state.
DEXTER HEREBY EXCLUDES INCIDENTAL AND
CONSEQUENTIAL DAMAGES, INCLUDING LOSS OF TIME,
INCONVENIENCE, LOSS OF USE, TOWING FEES, TELEPHONE
CALLS, COST OF MEALS OR LODGING, FOR ANY BREACH
OF ANY EXPRESS OR IMPLIED WARRANTY.
Some states do not allow limitations on how long an implied
warranty lasts, or the exclusion or limitation if incidental or
consequential damages, so the above exclusion or limitation may
not apply to you.
Inquiries regarding these warranties should be sent to:
Dexter Axle Company
P.O. Box 250
Elkhart, IN 46515
Note: Current publication “Operation Maintenance Service Manual”
can be found at www.dexteraxle.com.
-88-
Axle Identification
Axle Identification
In the unlikely event that you should require service assistance
from Dexter, please have the lot number of the axle available
when you call.
On all axles produced after April 2001, this nine digit number can
be found on the rear side of the axle beam approximately 18″ from
the curb side of the vehicle. Look for the words DEXTER AXLE
and the lot number will be located directly under the name.
-89-
Dexter Online Parts Store
From magnets and seals to complete brake and hub kits, Dexter offers a
complete line of genuine replacement parts for your trailer. Most products
are available in-stock and ready to ship within 24 hours direct to you from
the factory. With dedicated customer support and quick turnaround, the
Dexter Online Parts Store helps keep your trailer going.
• Hub Components
• Brake Components
• Suspension Components
• Complete Hub Kits
• Brake Assemblies & Kits
• Brake Controllers & Actuators
Ready for Immediate Shipment
Direct to Your Door
Visit us online at www.dexteraxle.com
-90-
Dexter Video Gallery
In keeping with our continual commitment to industry safety and the
development of innovative products, please feel free to view our ongoing
video gallery at www.dexteraxle.com/resources/videos or scan the
following QR codes. We are confident these videos will help educate and
promote the Dexter product line that you, as our customer, are investing
in.
Bearing
Maintenance
E/H Actuator
Installation
Electric Brakes E-Z Flex®
Suspension
E-Z Lube®
System
Genuine Brakes Genuine
Replacement
Parts
Leaf Spring
Axles
Manual Bleed
Hydraulic Disc
Medium Duty
Axles
Nev-R-Adjust®
Brakes
Power Bleed
Hydraulic Disc
Removable
Spindle
Sway Control Torflex®
Suspension Axles
-91-
Service Record
Date Service Performed Mileage
-92-
Service Record
Date Service Performed Mileage
Genuine Dexter axles and components are available
nationwide from our plant locations listed below or
through our network of distributors. Check our web site
for the distributor nearest you.
NO PART OF THIS CATALOG MAY BE REPRODUCED WITHOUT DEXTER AXLE’S PERMISSION.
ALL PART NUMBERS, DIMENSIONS AND SPECIFICATIONS IN THIS CATALOG ARE SUBJECT
TO CHANGE WITHOUT NOTICE.
Dexter – Headquarters
2900 Industrial Parkway East  Elkhart, Indiana 46516
Phone: 574-295-7888  Fax: 574-295-8666
www.dexteraxle.com
Dexter – Plt 12
301 West Pearl Street
Fremont, Indiana 46737
Phone: 260-495-5100
Fax: 260-495-1701
Dexter – Plt 13
500 South 7th Street
Albion, Indiana 46701
Phone: 260-636-2195
Fax: 260-636-3030
Dexter – Plt 15
500 Southeast 27th Street
El Reno, Oklahoma 73036
Phone: 405-262-6700
Fax: 405-262-9089
Dexter – Plt 21
199 Perimeter Road
Monticello, Georgia 31064
Phone: 706-468-6495
Fax: 706-468-2966
Ventline – Plt 39
902 South Division Street
Bristol, Indiana 46507
Phone: 574-848-4491
Fax: 574-848-4825
www.ventline.com
Dexter Door – Plt 39
902 South Division Street
Bristol, Indiana 46507
Phone: 574-848-4491
Fax: 574-848-4825
www.dexterdoor.com
Dexter – Plt 61
21611 Protecta Drive
Elkhart, Indiana 46516
Phone: 574-294-6651
Fax: 574-295-6626
Dexter – Plt 62
301 North Kennedy Street
Shawnee, Oklahoma 74801
Phone: 405-273-9315
Fax: 405-273-1054
UFP – Plt 24
135 Sunshine Lane
San Marcos, California 92069
Phone: 760-744-1610
Fax: 760-744-1616
UFP – Plt 25
1041 Baxter Lane
Winchester, Tennessee 37398
Phone: 931-967-5101
Fax: 931-967-1828
UFP
Plant 24
UFP
Plant 25
Dexter Headquarters
Plants 12, 13, 39, 61
Plant 21
Plants 15, 62
2900 Industrial Parkway East n Elkhart, IN 46516
Phone: 574-295-7888 n Fax: 574-295-8666
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www.dexteraxle.com