FORD F750 2011 12.G Owners Manual

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 lb-ft
(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.
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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.
EXHAUST BRAKE (IF EQUIPPED)
Note:The exhaust brake is
intended to help control vehicle
speed; it is not a vehicle stopping
device.
An exhaust brake is an optional
auxiliary braking system that assists,
but does not replace, the primary
service brake system. An on-off
switch on the instrument panel, in
combination with the accelerator
and clutch pedal switches, 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
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Operation
Push the rocker switch up to turn
the exhaust brake on. Push the
switch down to turn the brake off.
Starting engine
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 temperatures.
Driving downhill
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. 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 would to ascend the hill.
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 will not be able to select another gear because of maximum RPM
being governed.
Note:Maximum exhaust brake performance is related to the type of
transmission your vehicle is equipped with.
Note:Manual transmissions should be downshifted to the lowest gear
possible, without exceeding the maximum RPM limit of the engine. This
will maximize the exhaust brake’s retarding effect.
Note:Exhaust brakes will operate effectively with automatic
transmission, but performance will vary with engine speed and the gear
selected by the transmission.
Make sure the engine speed does not exceed the maximum allowable
engine RPM. Exceeding the maximum allowable engine RPM will 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.
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Note:Engine speed has a major influence of retarding performance.
When engine speed is maintained at the maximum allowable level, the
exhaust brake will operate at peak performance.
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.
•Engine temperature remains in the normal operating range.
•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.
•During a descent, the tachometer usually shows a drop in RPM
depending on the grade and the vehicle load.
•Do not expect a retarding effect similar to sudden hard application of
the service brakes. The exhaust brake retards the vehicle with a
smooth braking effect.
•Depending on the grade and vehicle load, you may or may not feel the
retarding force acting against your body when the brake is applied.
The brake’s retarding force is actually preventing the vehicle from
going much faster.
•Engine speed has a major effect on retarding performance, with higher
engine speeds permitting greater retarding ability.
•Engine brake performance is closely related to the type of
transmission your vehicle is equipped with. Downshifting the manual
transmission to the lowest gear possible, without exceeding the
maximum engine RPM limit, will maximize retarding performance.
Exhaust brakes will operate effectively with automatic transmissions,
but performance will vary with engine speed and the gear selected by
the transmission.
Make sure the exhaust brake is turned off before shutting off the engine.
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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.
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 downward, the greater the air
pressure is applied to the brakes. The lever will remain in place until
manually moved.
To release the trailer brakes, move the lever upward completely.
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TRAILER AIR SUPPLY AND PARKING BRAKE MODULAR
CONTROLS (IF EQUIPPED)
The trailer air supply valve delivers air to the trailer supply and will
automatically pop 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.
Initial charge
With the air system completely discharged, both knobs (1 and 2) will be
out. When the air pressure reaches 70 psi (483 kPa) the trailer air
supply (1 – red knob) may be pushed in and should stay in charging the
trailer air system and releasing the trailer brakes.
TRAILER
AIR SUPPLY
NOT FOR PARKING
TO
TOPULL
SUPPLY
EVACUATE
PUSH
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The parking brake (2–yellow knob) can now be pushed in and supply air
to the tractor spring brakes, releasing them.
Normal driving position
With both knobs pushed in, air is then supplied to both trailer and
tractor spring brakes, and all brakes are released.
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System park
With both knobs pushed in (normal driving position), the parking brakes
for both the tractor and trailer can be applied by pulling the parking
brake knob (2) out, exhausting air from the tractor spring brakes,
simultaneously causing the trailer air supply valve to pop out, applying
the trailer brakes.
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 (1) can be
pushed in to recharge the trailer air supply line. This mode may also be
used to park a combination vehicle with tractor spring brakes.
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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 (1) knob will
automatically pop out applying the emergency or parking brakes on the
trailer. If the trailer air supply (1) knob is manually held in and the air
pressure is reduced to approximately 30 psi (207 kPa), a tripper piston
within the valve will move, exhausting the trailer air supply, applying the
trailer brakes. Further reduction of air pressure, while holding the trailer
air supply knob in, will cause the parking brake knob to pop out at 25 psi
(172 kPa).
Actuation of trailer park (emergency) or tractor bobtail position
To actuate the trailer brakes only, pull out the trailer air supply knob (1).
The trailer brakes are now applied whether emergency or spring brakes
are used on the trailer.
This mode is also used when the tractor or truck with trailer is used
during bobtail operation.
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ANTI-LOCK BRAKE SYSTEM (ABS)
A noise from the hydraulic pump motor and pulsation in the pedal may
be observed during ABS braking events. Pedal pulsation coupled with
noise while braking under panic conditions or on loose gravel, bumps,
wet or snowy roads is normal and indicates proper functioning of the
vehicle’s ABS. If the vehicle has continuous vibration or shudder in the
steering wheel while braking, the vehicle should be inspected by a
qualified service technician.
The ABS operates by detecting the
onset of wheel lockup during brake
applications and compensating for
this tendency. The wheels are
prevented from locking even when
the brakes are firmly applied. The
accompanying illustration depicts
the advantage of an ABS-equipped
vehicle (on bottom) to a non-ABS
equipped vehicle (on top) during hard braking with loss of front braking
traction.
ABS warning light
The
ABSwarning light in the instrument cluster momentarily illuminates
when the ignition is turned on and the engine is off. If the light does not
illuminate momentarily at start up, remains on after the vehicle reaches
5–10 mph (8–16 km/h), or continues to flash, the ABS needs to be
serviced.
With the ABS light on, the anti-lock brake system is disabled and normal
braking is still effective unless the brake warning light also remains
illuminated. (If your parking brake warning light illuminates, have your
vehicle serviced immediately.)
Using ABS
•In an emergency or when maximum efficiency from the ABS is
required, apply continuous full force on the brake. The ABS will be
activated immediately, thus allowing you to retain full steering control
of your vehicle and, providing there is sufficient space, will enable you
to avoid obstacles and bring the vehicle to a controlled stop.
•The ABS does not decrease the time necessary to apply the brakes or
always reduce stopping distance. Always leave enough room between
your vehicle and the vehicle in front of you to stop.
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