2003 FORD F750 parking brake

Parking brake
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 R (Reverse) for vehicles equipped with manual
transmission or N (Neutral) for vehicles with automatic transmission.
Unexpected and possible sudden vehicle movement may occur if
these precautions are not taken.
If the service brakes should fail to operate while the vehicle is in motion,
you can make an emergency stop with the parking brake. The stopping
distance, however, will be much greater than normal. Repairs should be
made immediately to an inoperative air brake system circuit.
Parking brake control
Pull the yellow parking brake knob
out to apply the parking brake. Push
the knob in to release the parking
brake.
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
or N (Neutral) for automatic
transmission. Use of wheel chocks
is also recommended in hilly or
off-road usage.
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.PARKING
BRAKE
PULL TO
RELEASE
APPLY
PUSH TO
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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.
Releasing spring brake manually
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.
Block the wheels to prevent the vehicle from moving.
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 68 Nm
(50 lb-ft) 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 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.
Trailer brake (if equipped)
During normal operation, the trailer
brakes operate whenever the tractor
brakes are applied. A manual control
lever is provided so the trailer
brakes can be applied separately, if
required. To apply the trailer brakes,
pull the trailer brake control
downward to the APPLIED position.
Do not use the trailer brake
manual control lever for
parking.
Trailer air supply control (MV-3) (Tractor package)
The MV-3 control module is a two-button, push-pull control valve housed
in a single body which includes a dual circuit supply valve and a check
valve.
Operation
During initial charge, with the system completely discharged, both
buttons are out.
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When a trailer is hooked-up
correctly and system pressure
reaches 448 kPa (65 psi), the red
control (trailer supply) may be
pushed in and should stay in,
charging the trailer system and
releasing the trailer brakes.
The yellow control (parking brake)
may now be pushed in, which will
supply air to the tractor spring
brakes, releasing them.
Normal operating position
With both controls pushed in, air is supplied to the trailer and to the
tractor spring brakes; all brakes are released.
Actuation of trailer parking or emergency brakes
To actuate the trailer brakes only,
pull out the red control (trailer air
supply), exhausting the trailer
supply line. The trailer brakes are
now applied either by air emergency
or spring brakes, depending on the
type of trailer system. This mode
would be used to uncouple from the
trailer during bob-tail operation.
TRAILER
AIR SUPPLY
NOT FOR PARKING
PULL
TO
TOEVACUATE
PUSH
SUPPLY
PARKING
BRAKE
PULL
TOAPPLY
PUSH
TORELEASE
TRAILER
AIR SUPPLY
NOT FOR PARKING
PULL
TO
TOEVACUATE
PUSH
SUPPLY
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System park
With both controls in for normal run modes, the parking brakes on both
tractor and trailer may be actuated by pulling the yellow control (parking
brake) out, which exhausts the air from the tractor spring brakes and
simultaneously causes the red control (trailer supply) to pop out,
applying the trailer brakes. This complies with federal regulations stating
one control must apply all the parking brakes on the vehicle.
Trailer charge
If both controls are out when parking the combination vehicle and it is
desired to recharge the trailer (leaving the tractor spring brakes
applied), the trailer air supply control may be pushed in, repressurizing
the trailer supply line. This mode could also be used to park a
combination vehicle with air actuated emergency brakes on the trailer to
provide demonstrated parking capability with tractor spring brakes only.
Automatic application
With both controls in (in the normal run configuration), if the supply
pressure to the push-pull valves is reduced to approximately 240 to 310
kPa (35-45 psi), the red control (trailer supply valve) must pop out,
applying the emergency or parking brakes on the trailer. If the red
control is held in manually and the pressure decreases to approximately
172 to 240 kPa (25-35 psi), a tripper piston within the MV-3 valve will
move upward. This will exhaust the trailer supply, causing the required
non-override feature. The yellow control (parking brake) will pop out at
approximately 138 to 207 kPa (20-30 psi).
Reservoir selection
The number one service reservoir will at all times be selected as the
primary supply source for the MV-3. This is accomplished automatically
by the function of the dual circuit supply valve contained in the body of
the MV-3. Only in the event of a pressure drop of more than 207 kPa (30
psi) below that of the number two service reservoir will the dual circuit
supply valve shuttle and establish the front service reservoir as the
supply.
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Drain all the air brake reservoirs
daily, completely to 0 kPa/psi, by
opening the draincock at the bottom
of the tanks. 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.
STEERING
Your vehicle is equipped with power steering. Power steering uses energy
from the engine to decrease the driver’s effort in steering the vehicle.
Never hold the steering wheel to the extreme right or the extreme left
for more than a few seconds when the engine is running. This action
could damage the power steering pump.
Suspension and steering
The suspension and steering linkage in your vehicle should be inspected
periodically for the following:
•Spring leaf damage
•Spring sag
•Abnormal looseness
•Damaged seals
The following changes indicate a need to inspect and service your
vehicle:
•Changes in steering action
•Hard steering
•Excessive free play
•Unusual sounds when turning or parking
If the steering wanders or pulls
This condition can be caused by any of the following conditions:
•Underinflated tire(s) on any wheel(s)
•Front end out of alignment
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Air suspension dump valve
The dump valve switch activates the
dump valve. The dump valve
releases air from the air springs and
lowers the rear suspension, allowing
you to back under a low trailer
when necessary.
DRIVING WITH AN AUTOMATIC TRANSMISSION (IF EQUIPPED)
Allison automatic transmission
Do not allow your vehicle to coast in N (Neutral). Transmission
braking is not available in N (Neutral). Allowing the vehicle to
coast in N (Neutral) could result in loss of vehicle control and severe
transmission damage.
The Allison automatic transmissions are a torque converter type, full
power shifting and fully automatic. They also have the added flexibility
of manually selecting and holding in the lower drive ranges which permit
the drive selection of the most suitable gear range to match varying road
and load conditions. To prevent destructive overspeeding of the engine,
the hold feature is not infinite, resulting in upshifts from the hold range
to the next higher range at some speed above the no-load governed
speed of the engine.
Allison AT-545
These transmissions have no P (Park) position. Before leaving
the driver’s seat, always shift into N (Neutral) and set the
parking brake. Shut off the engine and remove your ignition key.
Always use wheel chocks for hilly or off-road parking. Unexpected and
possibly sudden vehicle movement may occur if these precautions are
not taken.
This transmission provides four forward speeds and one reverse range.
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R (Reverse)
Use this position to back the vehicle. Completely stop the vehicle before
shifting from R (Reverse) to any forward gear (1, 2, 3 or D). The reverse
warning signal will sound when the selector is in R (Reverse). Reverse
has only one gear and provides the greatest gear reduction.
N (Neutral)
Place the selector in N (Neutral) before starting the engine. Shift to N
(Neutral) and set the parking brake any time the engine is to be running
while the operator is not at the controls. The engine should be at idle
speed when any shift from N (Neutral) to a drive range is made.
D (Drive-Normal driving position)
The transmission starts in first gear and automatically shifts through
second, third and fourth depending on load and speed demands. This
range is used for highway driving under normal conditions.
3 and 2 (Third and Second)
Use these ranges when road, load or traffic conditions require a lower
gear. These ranges provide greater engine braking than D (Drive). When
conditions are improved that no longer require these lower gears, shift
back to D (Drive).
1 (First)
The transmission has to be manually shifted into 1 (First) and will not
shift into a higher gear. This range is used for extra heavy loads or where
maximum reduction is required.
Allison MD Series transmissions
These transmissions have no P (Park) position. Before leaving
the driver’s seat, always shift into N (Neutral) and set the
parking brake. Shut off the engine and remove your ignition key.
Always use wheel chocks for hilly or off-road parking. Unexpected and
possibly sudden vehicle movement may occur if these precautions are
not taken.
These transmissions are electronically controlled and have a push button
shifter. MD transmissions are available in five- or six-speed driving
ranges.
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