brake FORD F750 2012 12.G Owner's Guide

3. Select the appropriate drive gear.
4. Push and hold the yellow, dash-mounted parking brake knob until
the
light turns off, then release.
WARNING:Hold the brake pedal down while moving the
gearshift lever from position to position. If the brake pedal is not
held down, the vehicle may move unexpectedly resulting in property
damage, personal injury or death.
Parking brake light illumination due to low air pressure
If at any time during vehicle operation air pressure becomes too low, the
parking brake may apply and the
light turns on.
If the parking brake is applied due to low air pressure, immediate service
is required to the parking brake system.
Parking brake warning system (hydraulic brake vehicles only)
If the
light blinks and a chime sounds when pulling the yellow
control knob out, this indicates the parking brake is not functioning
properly; seek service for the parking brake immediately.
With the ignition key not in the run position:
•A chime sounds if the parking brake remains released (or in an
unknown state). The chime extinguishes in approximately eight
minutes or until the parking brake is applied. Seek service for the
parking brake immediately.
Parking brake light (
) operation (light only works when the ignition
key is in the run position):
•On - Parking brake applied
•Off - Parking brake released and no faults/malfunctions
•Blink and chime - Parking brake released (or unknown) and
faults/malfunctions exist
Releasing spring manually
WARNING:Do not attempt to disassemble the parking brake
chamber under any circumstances. The high spring load may
cause serious injury.
If hydraulic pressure is released from the spring brake chamber the
power spring applies the brake and, unless hydraulic pressure can be
re-established, the spring brake must be released as follows in order to
move the vehicle.
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WARNING:Block the wheels to help prevent the vehicle from
moving.
WARNING:Unexpected and possibly sudden vehicle movement
may occur if these precautions are not taken.
Loosen the jam nut (1) and un-thread the adjustment rod (2) from the
chamber to reduce tension on the cable (3). Continue to un-thread the
adjustment rod all the way and remove it from the chamber. The nut and
shaft are metric.
AIR BRAKES (IF EQUIPPED)
General air brake information
After starting the engine, give the air compressor time to build up the air
pressure to 60 psi (414 kPa) before moving the vehicle.
WARNING: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.
WARNING:Avoid repeated light application of the brake pedal.
This depletes air pressure faster and could result in loss of
braking capability.
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Periodically check the air pressure
gauge while driving. Pressure should
range between approximately
100–125 psi (690–862 kPa). The air
compressor governor cut-in and
cut-out 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 condition may be caused by excessive brake applications depleting
the system air pressure. If this condition occurs, stop driving the vehicle
until the compressor has fully recharged the air system.
WARNING:Do not move the vehicle when the air pressure is
insufficient because the brake system may be inoperative.
Select a gear ratio to help slow your vehicle before descending grades.
Supplement with brakes as required to safely slow the vehicle and avoid
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 orange
stripe is painted on the air chamber push rod at the slack adjuster stroke
dimension which requires service when visible during brake application.
Air brake inspection and adjustment or repairs should be performed by a
qualified service technician in accordance with the instructions in the
service manual.
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Cam brakes - automatic slack adjusters
Standard air brakes (cam) are
equipped with automatic brake
adjusters. Automatic adjustment
occurs during brake applications.
Inspect brakes for proper
adjustment at the intervals listed in
theScheduled Maintenance Guide
chapter.
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.
Emergency air brake
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. These systems are all controlled by the brake pedal in the
same manner as for normal stops.
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.
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Air brake reservoir draining
WARNING:Failure to drain air brake reservoirs can result in a
reduction or loss of braking ability due to fluid accumulation in
the reservoir and/or possible freeze-up during cold weather.
Drain all the air brake reservoirs
daily, completely to 0 psi/kPa, by
opening the draincock at the ends
of the tanks (where accessible.
Pull-chains are used when the
drains are undercab or otherwise
inaccessible). Close draincock after
complete draining. Air tanks
equipped with automatic moisture
ejector valves may also be drained
manually as required to maintain a
dry air system. Contact your dealer if you are unsure of the air reservoir
locations or the draining procedure.
Parking brake
WARNING:Do not use the gearshift selector in place of the
parking brake; unexpected and possible sudden vehicle
movement may occur if these precautions are not taken. Always set
the parking brake fully AND make sure the gearshift selector is in R
(Reverse) for vehicles equipped with manual transmission, N (Neutral)
for vehicles with automatic transmission (except Allison 2200
transmission) or P (Park) (Allison 2200 transmission).
If the service brakes should fail to operate while the vehicle is in motion,
you can make an emergency stop with the parking brake. Since the
parking brake only applies stopping power to the rear wheels, the
vehicle’s stopping distance greatly increases and the handling of the
vehicle is adversely affected. Repairs should be made immediately to an
inoperative air brake system circuit.
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Parking brake control (knob)
Pull the yellow parking brake knob
out to apply the parking brake. Push
the knob in to release the parking
brake.
WARNING:This control is used for parking only. Do not leave
the vehicle unattended after setting the parking brake without
placing the transmission in R (Reverse) for manual transmission, N
(Neutral) for automatic transmission (except Allison 2200
transmission) or P (Park) (Allison 2200 transmission). Use of wheel
chocks is also recommended in hilly or off-road usage.
The
light illuminates and
remains illuminated (when the
ignition is turned to the on position)
until the parking brake is released.
Releasing spring brake with air pressure
The air system in all vehicles with spring-actuated rear wheel parking
brakes is equipped with a tank valve located on the supply or service air
tank for connection to an outside air supply. The valve permits the
system to be recharged with air from an outside source, releasing the
spring-actuated parking brakes. The vehicle may then be towed in an
emergency.
An outside air source can be used only if the protected system is in
operating condition. If air pressure cannot be restored in the protected
air system, the spring-actuated brakes must be released manually.
P
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Releasing spring brake manually
WARNING: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.
If air pressure is released from the spring brake chamber the power spring
applies the brake and, unless air pressure can be re-established, the spring
brake must be released as follows in order to move the vehicle.
WARNING:Block the wheels to help prevent the vehicle from
moving.
WARNING:Unexpected and possibly sudden vehicle movement
may occur if these precautions are not taken.
Impact wrenches should not be used as they may damage the piston and
prevent proper caging of the spring. Do not apply more than 50 ft-lb
(68 N•m) torque to the release bolt nut.
1. Remove the stud tool and nut
from the carrying pocket on the
brake chamber assembly.
2. Remove the access plug from the
end of the spring chamber.
3. Insert the release stud through
the opening in the chamber and into
the spring pressure plate.
4. Turn the release stud one-quarter
turn to engage the stud tangs with
the slot in the pressure plate. Keep
the stud engaged and install the nut
on the release stud.
5. Tighten the nut until the spring is
fully caged and the brakes are
released. Do not loosen or remove
the release stud and nut unless the brake chamber is completely
assembled and is securely clamped.
6. When the air pressure is restored, unscrew and remove the release
stud and install in the carrying pocket. Install the access plug.
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EXHAUST BRAKE (IF EQUIPPED)
An exhaust brake is an auxiliary braking system that assists, but does
not replace, the primary service brake system. It is intended to help
control vehicle speed; it is not a vehicle stopping device.
A switch on the instrument panel, in
combination with the accelerator
and clutch pedal, allows the
operator to make maximum use of
the exhaust brake in the following
conditions:
•off-highway driving
•mountain driving
•heavy traffic
•high speed highway driving
To operate the brake, push the switch up to turn it on. Push the switch
down to turn it off.
Note:Before starting the engine, make sure that the exhaust brake
switch is pushed down to the off position. Do not turn the exhaust brake
on until the engine has reached normal operating temperature.
While approaching a steep grade, make sure that the exhaust brake
switch is in the on position. The exhaust brake actuates as soon as you
remove your foot from the accelerator pedal.
Before descending a hill or steep grade always select the proper gear. If
the transmission is taken out of gear while descending, it is possible that
you can’t select another gear because of maximum RPM being governed.
Make sure the engine speed does not exceed the maximum allowable
engine RPM; exceeding the maximum allowable engine RPM can result in
damage to the engine. Apply the service brakes to reduce the engine
RPM or make a slower descent by using a lower gear.
While going down the grade, use a low enough gear to descend safely
with a minimum application of the service brakes. As a general guideline,
use the same gear as you use to ascend the hill.
Note:Engine speed has a major influence of retarding performance.
When engine speed is maintained at the maximum allowable level, the
exhaust brake operates at peak performance.
Note:Maximum exhaust brake performance is related to the type of
transmission your vehicle is equipped with.
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Note:Manual transmissions should be downshifted to the lowest gear
possible, without exceeding the maximum RPM limit of the engine. This
maximizes the exhaust brake’s retarding effect.
Note:Exhaust brakes operate effectively with automatic transmissions,
but performance varies with engine speed and the gear selected by the
transmission.
Note:Installing an exhaust or auxiliary brake does not necessarily
protect the engine from exceeding maximum governed speed. The
primary brakes should be used to make sure the engine never exceeds
maximum governed speed under any conditions.
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.
Exhaust brake operating characteristics
When you remove your feet from both the accelerator and clutch pedals
and the exhaust brake switch is in the on position, the exhaust brake is
activated. The following conditions should exist if the brake is operating
properly:
•A slight change in the sound of the engine when the exhaust brake is
activated.
•A smooth braking effect; do not expect a retarding effect similar to
sudden, hard application of the service brakes.
•The retarding force possibly felt acting against your body when the
brake is applied, depending on the grade and vehicle load. The brake’s
retarding force is actually preventing the vehicle from going much
faster.
•Engine temperature remains in the normal operating range.
•During a descent, the tachometer usually shows a drop in engine RPM
depending on the grade and the vehicle load.
•Road speed usually decreases when the exhaust brake is applied
during a descent, except when the vehicle is carrying a heavy load or
the grade is extremely steep. In these instances, you may need to
apply the service brakes occasionally.
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TRAILER BRAKE HAND CONTROL (IF EQUIPPED)
The hand control, located on the
right-hand side of the instrument
panel, is used to apply the trailer
service brakes which are
independent of the truck or tractor
service brakes.
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 operates a valve that provides gradual control of air
pressure applied; when the valve is only partially applied, the trailer
brakes can be overridden by pressing fully on the brake pedal.
To apply the trailer brakes using the hand control, move the lever
downward. The further the lever is pushed 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 is
decreased to approximately 35 psi
(249 kPa).
The parking brake controls the
spring brakes on the tractor. When
the knob is pulled out it causes the
trailer supply valve to pop out,
applying both the tractor and trailer
parking brakes. The trailer brakes
may be independently released by pushing only the trailer air supply
valve in.
TRAILER
AIR SUPPLY
NOT FOR PARKING
TO
TOPULL
SUPPLY
EVACUATE
PUSH
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