2015 FORD F750 brake

Trailer Charge
If both knobs are out, and you want to recharge the trailer while leaving
the tractor spring brakes applied, the trailer air supply (A) can be
pushed in to recharge the trailer air supply line. You can also use this
mode to park a combination vehicle with tractor spring brakes.
Automatic Application
If both knobs are pushed in and the brake system air pressure is reduced
to approximately 35 psi (249 kPa), the trailer air supply (A) knob
automatically pops out applying the emergency or parking brakes on the
trailer. If the trailer air supply (A) knob is manually held in and the air
pressure is reduced to approximately 30 psi (207 kPa), a tripper piston
within the valve moves, exhausting the trailer air supply, applying the
trailer brakes. Further reduction of air pressure, while holding the trailer
air supply knob in, causes the parking brake knob to pop out at 25 psi
(172 kPa).
B
AB
A
B
A
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Actuation of Trailer Park (Emergency) or Tractor Bobtail Position
To actuate the trailer brakes only, pull out the trailer air supply knob
(A). This applies the trailer brakes whether the trailer uses emergency
or spring brakes.
You can also use this mode when the tractor or truck with trailer is used
during bobtail operation.
PARKING BRAKE
Hydraulic Brakes
WARNING:Do not use the gearshift selector in place of the
parking brake. Always set the parking brake fully AND make sure
the gearshift selector is in positionRfor vehicles equipped with a
manual transmission or positionP (if equipped)orNfor vehicles
equipped with an automatic transmission. Use of wheel chocks is also
recommended in hilly or off-road usage. Unexpected and possible
sudden vehicle movement may occur if these precautions are not taken.
WARNING:If the parking brake is fully released but the parking
brake warning lamp remains illuminated, the brakes may not be
working properly. See your dealer or a qualified service technician.
Apply the parking brake whenever the vehicle is parked. To set the
parking brake, pull the handle up until it snaps into the locked position.
When the parking brake is out of adjustment, seek service immediately.
The parking brake warning lamp in the instrument cluster
illuminates, and remains illuminated (when you switch on the
ignition), until you release the parking brake.
B
A
P
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Push the palm release lever (A) on
the parking brake handle (B) and
push down as far as possible to
release the brake. Driving with the
parking brake on causes the brakes
to wear out quickly and reduces
fuel economy.
We recommend you not use the parking brake to stop a moving vehicle.
However, if the normal brakes fail, you can use the parking brake to stop
your vehicle in an emergency. Since the parking brake only applies
retardation to the rear wheels, the vehicle’s stopping distance increases
greatly and the handling of your vehicle is adversely affected.
Power Park (Hydraulic Brake Vehicles Only)
This feature uses a brake chamber mounted on the chassis to power a
spring-applied, hydraulically released driveline parking brake.
The park brake dash-mounted, yellow knob-type switch controls the
Power Park Brake. The switch has three positions: apply (out), neutral
(central), and release (in). The switch is spring-loaded to return to the
neutral (central) position after pushing or pulling it.
There is no visual indication at the knob that the parking brake
is applied or released; check the instrument cluster. If the light
is illuminated, the parking brake is applied.
Applying the Parking Brake
Pull the yellow, dash-mounted parking brake knob. The parking brake
light illuminates indicating that the parking brake has been successfully
set.
Note:If the light blinks and a warning tone sounds when you pull the
control knob, the parking brake is not functioning properly. Seek
immediate service from your dealer. SeeParking brake warning
systemin this section.
Releasing the Parking Brake
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.
A
B
P
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Note:Read and understand the following steps and perform them
whenever you prepare to drive the vehicle.
Note:The parking brake does not disengage unless sufficient system air
pressure is available.
If your vehicle is equipped with a dash-mounted push button (Allison
3000 Series) or steering column-mounted (Allison 2200 and 2500) gear
selector:
1. Press and hold the service brake pedal while the engine is running.
2. Select the appropriate drive gear.
3. Push and hold the yellow, dash-mounted parking brake knob until the
parking brake light turns off, then release.
If your vehicle is equipped with a manual transmission:
1. Press and hold the service brake pedal while the engine is running.
2. Press and hold the clutch pedal.
3. Select the appropriate drive gear.
4. Push and hold the yellow, dash-mounted parking brake knob until the
parking brake light turns off, then release.
Parking Brake Light Illumination Due to Low Air Pressure
If the air pressure becomes too low at any time during vehicle operation,
the parking brake may apply and the parking brake light turns on.
If the parking brake applies due to low air pressure, immediate service is
required to the parking brake system.
Parking Brake Warning System
If the parking brake light blinks and a tone 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 tone sounds if the parking brake remains released (or in an
unknown state). The tone stops in approximately eight minutes or
until the parking brake is applied. Seek service for the parking brake
immediately.
Diesel engines:Parking brake light operation (the light only works
when the ignition key is in the run position):
•On:Parking brake applied.
•Off:Parking brake released and no faults or malfunctions.
•Blink and tone:Parking brake released (or in an unknown state)
and faults or malfunctions exist.
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Releasing Spring Manually
WARNING:Do not attempt to disassemble the parking brake
chamber under any circumstances. The high spring load may
cause serious injury.
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.
If you release hydraulic pressure from the spring brake chamber the
power spring applies the brake and, unless hydraulic pressure can be
re-established, you must release the spring brake as follows in order to
move your vehicle.
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. The nut and
shaft are metric.
CA
B
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Air Brakes
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 position
Rfor vehicles equipped with manual transmission or positionN(except
Allison 2200 transmission) orP(Allison 2200 transmission) for vehicles
with automatic transmission.
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.
WARNING:This control is used for parking only. Do not leave
the vehicle unattended after setting the parking brake without
placing the transmission inpositionRfor vehicles equipped with manual
transmission or positionN(except Allison 2200 transmission) orP
(Allison 2200 transmission) for vehicles with automatic transmission.
Use of wheel chocks is also recommended in hilly or off-road usage.
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 tank valve located on the supply or service air
tank for connection to an outside air supply. The valve lets you recharge
P
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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
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 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.
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.
Do not use impact wrenches as they may damage the piston and prevent
proper caging of the spring. Do not apply more than 50 foot-pounds
(68 newton-meters) 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.
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4. Turn the release stud14-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 brakes released.
Do not loosen or remove the release
stud and nut unless you completely assemble and securely clamp the
brake chamber.
6. After restoring the air pressure, unscrew and remove the release stud
and install in the carrying pocket. Install the access plug.
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