
Loosen the jam nut (A) and un-thread the
adjustment rod (B) from the chamber to
reduce tension on the cable (C). Continue
to un-thread the adjustment rod all the
way and remove it from the chamber.
Air Brakes
WARNING
This control is used for parking only.
Do not leave the vehicle unattended
after setting the parking brake
without placing the transmission park (P).
Use of wheel chocks is also recommended
in hilly or off-road usage. If the service brakes should fail to operate
while your vehicle is moving, you can make
an emergency stop with the parking brake.
Since the parking brake only applies
stopping power to the rear wheels, your
vehicle
’s stopping distance greatly
increases and the handling of your vehicle
is adversely affected. Make repairs
immediately to an inoperative air brake
system circuit. Pull the yellow parking brake knob out to
apply the parking brake. Push the knob in
to release the parking brake.
The parking brake light
illuminates and remains
illuminated (when you switch
the ignition to the on position) until you
release the parking brake. Releasing Spring Brake with Air
Pressure
The air system in all vehicles with
spring-actuated rear wheel parking brakes
is equipped with a valve located on the
governor for connection to an outside air
supply. The valve lets you recharge the
system with air from an outside source,
releasing the spring-actuated parking
brakes. Your vehicle is now ready to tow in
an emergency.
You can only use an outside air source if
the protected system is in operating
condition. If you cannot restore air pressure
in the protected air system, you must
release the spring-actuated brakes
manually.
Releasing Spring Manually
WARNINGS
Do not attempt to disassemble the
parking brake chamber under any
circumstances. The high spring load
may cause serious injury if the chamber
clamps are removed. Block the wheels to help prevent the
vehicle from moving.
Unexpected and possibly sudden
vehicle movement may occur if these
precautions are not taken.
If you release air pressure from the spring
brake chamber, the power spring applies
the brake and, unless air pressure can be
re-established, you must release the spring
brake as follows in order to move your
vehicle.
Do not use impact wrenches as they may
damage the piston and prevent proper
caging of the spring. Do not apply more
than 50 lb.ft (68 Nm) to the release bolt
nut.
123
F650750 (TBC), enUSA, First Printing BrakesE210341 E210346

AIR BRAKES
WARNINGS
Do not drive or continue to drive if the
low air pressure buzzer is sounding
or the brake warning light is lit. These
warnings indicate that air pressure is not
to normal operating level. Continued use
of the vehicle could result in loss of braking
ability. Avoid repeated light application of
the brake pedal. This depletes air
pressure faster and could result in
loss of braking capability. Do not move the vehicle when the
air pressure is insufficient because
the brake system may be inoperative.
After starting the engine, give the air
compressor time to build up the air
pressure to 60 psi (414 kPa) before moving
your vehicle. Periodically check the air pressure gauge
while driving. Pressure should range
between approximately 100 psi (690 kPa)
to
130 psi (896 kPa). The air compressor
governor cut-in and cutout pressure
settings are set at the factory and are not
adjustable. When air pressure is insufficient
(below
60 psi (414 kPa)), a
warning light illuminates and a
buzzer sounds when the ignition is in the
on position. This may happen because
excessive brake applications are depleting
the system air pressure. If this condition
occurs, stop driving your vehicle until the
compressor has fully recharged the air
system.
Select a gear ratio to help slow your vehicle
before descending grades. Supplementing
with brakes, as required, help to safely slow
the vehicle and avoids overspeeding the
engine.
Air Chamber Stroke Indication
Air chamber push rods have orange stroke
indicator markers that warn when the
braking system requires adjustment or
repair. The painted orange indicator is on
the air chamber push rod at the slack
adjuster stroke dimension that requires
service when visible during brake
application.
A qualified service technician should
perform air brake inspection and
adjustment or repairs keeping to the
instructions in the service manual.
Cam Brakes - Automatic Slack
Adjusters WARNING
Do not manually adjust the
automatic slack adjusters to correct
excessive push rod stroke as it may
result in reduced brake effectiveness and
a vehicle crash. Excessive push rod stroke
indicates that a problem exists with the
automatic adjuster, with the installation
of the adjuster, or with foundation brake
components that manual adjustment does
not remedy. Seek service from a qualified
facility for excessive push rod stroke. 125
F650750 (TBC), enUSA, First Printing BrakesE210336 E206772

Standard air brakes (cam) are equipped
with automatic brake adjusters. Automatic
adjustment occurs during brake
applications. Inspect brakes for proper
adjustment at the specified intervals. See
Scheduled Maintenance (page 314).
Emergency Air Brake WARNING
Do not continue to operate the
vehicle with a failure of one of the
brake systems. Take the vehicle to
your dealer for service immediately. All vehicles are equipped with a dual brake
system. In the unlikely event of a failure of
one system, the second system functions
for emergency stopping. The brake pedal
controls all these systems in the same
manner as for normal stops.
EXHAUST BRAKE
WARNING
The exhaust brake is not
recommended for use on slippery or
low traction road surfaces. Under
these conditions a loss of vehicle control
could occur. Note:
Installing an exhaust or auxiliary
brake does not necessarily protect the
engine from exceeding maximum governed
speed. Use the primary brakes to make sure
the engine never exceeds maximum
governed speed under any circumstance.
Note: Before starting the engine, make sure
that the exhaust brake switch is in the off
position. Do not turn the exhaust brake on
until the engine has reached normal
operating temperature.
Note: Maximum exhaust brake
performance relates to the type of
transmission your vehicle has.
Note: Engine speed has a major influence
of retarding performance. When engine
speed stays at the maximum allowable
level, the exhaust brake operates at peak
performance.
Note: Exhaust brakes operate effectively
with automatic transmissions, but
performance varies with engine speed and
the gear selected by the transmission.
An exhaust brake is an auxiliary braking
system that assists, but does not replace,
the primary service brake system. It helps
control vehicle speed; it is not a
vehicle-stopping device.
126
F650750 (TBC), enUSA, First Printing BrakesE210337

TRAILER BRAKES
Trailer Brake Hand Control (If Equipped)
WARNING
The hand control should never be
used to apply the brakes when the
tractor and trailer are parked
unattended. Air may leak from the system
and the vehicle could possibly move,
resulting in possible property damage,
personal injury or death. The hand control is located on the
right-hand side of the instrument panel. It
applies the trailer service brakes, which are
independent of the truck or tractor service
brakes.
It operates a valve that provides gradual
control of air pressure applied. When the
valve is only partially applied, you can
override the trailer brakes by pressing fully
on the brake pedal.
To apply the trailer brakes using the hand
control, move the lever downward. The
further you push the lever down, the
greater the air pressure is applied to the
brakes. The lever remains in place until
manually moved. To release the trailer brakes, move the
lever up completely.
Trailer Air Supply and Parking
Brake Modular Controls (If Equipped)
The trailer air supply valve delivers air to
the trailer supply and automatically pops
out, shutting off the trailer supply, if
pressure decreases to approximately 35 psi
(249 kPa)
.
The parking brake controls the spring
brakes on the tractor. When you pull the
knob out, it causes the trailer supply valve
to pop out, applying both the tractor and
trailer parking brakes. You can
independently release the trailer brakes by
pushing only the trailer air supply valve in.
128
F650750 (TBC), enUSA, First Printing BrakesE210339 E210340
A
B
12
A320
A E210341

PRINCIPLE OF OPERATION
The traction control system helps avoid
drive wheel spin and loss of traction.
If your vehicle begins to slide, the system
applies the brakes to individual wheels
and, when needed, reduces engine power
at the same time. If the wheels spin when
accelerating on slippery or loose surfaces,
the system reduces engine power in order
to increase traction.
Note:
The system does not apply the brakes
when vehicle speed is above 25 mph
(40 km/h).
USING TRACTION CONTROL -
VEHICLES WITH: AIR BRAKES WARNING
Aggressive driving in any road
conditions can cause you to lose
control of your vehicle increasing the
risk of severe personal injury or property
damage. The occurrence of a traction
control event is an indication that at least
some of the tires have exceeded their
ability to grip the road; this may lead to an
increased risk of loss of vehicle control,
vehicle rollover, personal injury and death.
If you experience a severe road event,
SLOW DOWN. Press the switch to select Off Road or
Mud/Snow traction mode. This is
beneficial when your vehicle is stuck in
snow or on a slippery road surface. This
mode allows excess wheel spin to dig your
vehicle out and allows you to rock your
vehicle.
Press the switch again to select standard
traction control. The system automatically
selects standard traction control at the
next ignition cycle. System Indicator Light
Note:
If the traction control light does not
flash during a traction control event or stays
illuminated, the system is not functioning
properly. Take your vehicle to an authorized
dealer for service.
During traction control operation, the
traction control light flashes rapidly and
the engine does not rev-up when you press
further on the accelerator. This is normal
and is no reason for concern.
In Off Road or Mud/Snow mode, the
traction control light illuminates and
flashes slowly. If a traction event occurs,
in either mode, the light flashes rapidly.
USING TRACTION CONTROL -
VEHICLES WITH: HYDRAULIC
BRAKES WARNING
Aggressive driving in any road
conditions can cause you to lose
control of your vehicle increasing the
risk of severe personal injury or property
damage. The occurrence of a traction
control event is an indication that at least
some of the tires have exceeded their
ability to grip the road; this may lead to an
increased risk of loss of vehicle control,
vehicle rollover, personal injury and death.
If you experience a severe road event,
SLOW DOWN. The system automatically turns on each
time you switch the ignition on.
Use the traction control switch on the
instrument panel to switch the system off
or on.
If your vehicle is stuck in mud or snow,
switching traction control off may be
beneficial as this allows the wheels to spin.
132
F650750 (TBC), enUSA, First Printing Traction Control

AIR SUSPENSION (If Equipped)
Note: Do not operate your vehicle without
air in the suspension springs. Operating your
vehicle without air in the suspension springs
damages the suspension, degrades ride
performance and may cause property
damage.
The air suspension system automatically
adjusts to different loads to maintain a
constant frame height, allows for ease of
vehicle loading, provides improved vehicle
ride, and increased driver comfort.
Air Suspension Dump Button Note:
The suspension dumps air when the
ignition is in the accessory or on position,
but fills only when the ignition is in the on
position.
A button located on the instrument panel
controls the system. It operates only when
the ignition is in the accessory or on
position and the air tanks have sufficient
pressure to fill the air springs. When you
turn off the ignition, the suspension
remains in whatever state it was last set.
Pressing and holding the button for two
seconds exhausts air from the air springs,
lowering the frame for loading. Pressing
and holding the button for two seconds
fills the air springs so your vehicle remains
at normal ride height. System Indicator Light
The air suspension indicator light
illuminates when using the button to
release air pressure in the rear air springs.
Never drive your vehicle when the warning
lamp is illuminated and there is low (or no)
air pressure in the springs.
Connecting and Disconnecting a
Trailer with Air Suspension and Air
Suspension Dump Button
When connecting to a trailer:
•
Press and hold the button for two
seconds to exhaust air from the air
suspension system.
• Press and hold the button for two
seconds, and then raise the landing
gear after making the connection to
the trailer.
When disconnecting the trailer:
• Lower the landing gear, and then press
and hold the button for two seconds.
• Disconnect the brake hoses, trailer-side
and rear light connectors, then pull the
release lever on the fifth wheel.
You must fill the air springs before
operating with a trailer or operating in the
bobtail mode.
Suspension Conversions WARNING
When operating a loaded vehicle, the
driver must keep all adjustable axles
on the ground at all times, supporting
their share of the vehicle ’s load. Failure to
do so can overload other axles, tires,
wheels, springs, steering components,
brakes and frames, resulting in early
component failure, loss of vehicle control,
possible property damage and personal
injury. 138
F650750 (TBC), enUSA, First Printing Load CarryingE213409

We do not recommend performing, or
approve of, suspension conversions.
However, we understand that, on occasion,
others install aftermarket add-on
suspensions on the truck chassis that allow
operator control for weight transfer from
other axles (such as air lift axles).
139
F650750 (TBC), enUSA, First Printing Load Carrying

ESSENTIAL TOWING CHECKS
See Load limits in the Load Carrying
chapter for load specification terms found
on the tire label and Safety Compliance
label and instructions on calculating your
vehicle's load.
Remember to account for the trailer
tongue weight as part of your vehicle load
when calculating the total vehicle weight.
Hitches
Do not use a hitch that either clamps onto
the bumper or attaches to the axle. You
must distribute the load in your trailer so
that 10-15% of the total weight of the
trailer is on the tongue.
Safety Chains
Note: Do not attach safety chains to the
bumper.
Always connect the safety chains to the
frame or hook retainers of your vehicle
hitch.
To connect the safety chains, cross the
chains under the trailer tongue and allow
enough slack for turning tight corners. Do
not allow the chains to drag on the ground.
Trailer Brakes WARNING
Do not connect a trailer's hydraulic
brake system directly to your
vehicle's brake system. Your vehicle
may not have enough braking power and
your chances of having a collision greatly
increase. Electric brakes and manual, automatic or
surge-type trailer brakes are safe if you
install them properly and adjust them to
the manufacturer's specifications. The
trailer brakes must meet local and federal
regulations. The rating for the tow vehicle's braking
system operation is at the gross vehicle
weight rating, not the gross combined
weight rating.
Trailer Lamps
WARNING
Never connect any trailer lamp wiring
to the vehicle's tail lamp wiring; this
may damage the electrical system
resulting in fire. Contact your authorized
dealer as soon as possible for assistance
in proper trailer tow wiring installation.
Additional electrical equipment may be
required. Trailer lamps are required on most towed
vehicles. Make sure all running lights, brake
lights, turn signals and hazard lights are
working.
Before Towing a Trailer
Practice turning, stopping and backing up
to get the feel of your vehicle-trailer
combination before starting on a trip.
When turning, make wider turns so the
trailer wheels clear curbs and other
obstacles.
When Towing a Trailer
•
Check your hitch, electrical connections
and trailer wheel lug nuts thoroughly
after you have traveled 50 miles (80
kilometers).
• When stopped in congested or heavy
traffic during hot weather, place the
gearshift in position
P or position N to
aid engine and transmission cooling
and to help air conditioning
performance.
• Turn off the speed control with heavy
loads or in hilly terrain. The speed
control may turn off automatically
when you are towing on long, steep
grades.
142
F650750 (TBC), enUSA, First Printing Towing