2001 FORD F650 brakes

Occasional or intermittent brake squeal may result from environmental
conditions such as cold, hot, wet, snow, salt, mud, etc. This condition will
not affect braking effectiveness. The brakes should be checked only if
squeal occurs continuously with every application.
If brakes do not grip well
²If you have been driving through deep water, gently apply the brakes
several times while the vehicle is moving slowly.
²Let the brakes cool if you have been using them excessively, as in
mountain driving or after several fast, high speed stops.
²Check brake adjustment.
²Check brake linings for excessive wear.
²Check system air pressure.
Air brakes
After starting the engine, give the air compressor time to build up the air
pressure to 414 kPa (60 psi) before moving the vehicle.
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 will
deplete air pressure faster and could result in loss of braking
capability.
Periodically check the air pressure
gauge while driving. Pressure should
range between approximately 703 to
930 kPa (105-135 psi). The air
compressor governor cut-in and
cut-out pressure settings are preset
at the factory and are not
adjustable.
0 30 12090 60
150AIR
PRESSUREPSI
Driving
114

When air pressure is insufficient
(below 534 kPa [60 psi]), 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. Do not move the
vehicle in this condition 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
All Ford air chamber push rods have orange stroke indicator stripes that
alert the operator when the braking system requires adjustment or
repair. The orange stripe is painted on the air chamber push rod at the
slack adjuster readjustment stroke dimension.
Air brake inspection and adjustment should be performed by a qualified
service technician in accordance with the instructions in the Ford Truck
Service Manual.
Cam brakesÐautomatic slack adjusters
Standard air brakes (cam) are
equipped with automatic brake
adjusters. Automatic adjustment
occurs during forward and reverse
brake applications. Inspect brakes
for proper adjustment at the
intervals listed in the vehicle Service
Maintenance Guide.
!
BRAKE
Driving
115

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 will function for emergency
stopping. These systems are all controlled by the brake pedal in the
same manner as for normal stops.
Do not continue to operate the vehicle with a failure of one of
the systems. Take the vehicle to your dealer for service
immediately.
Anti-lock braking system (if equipped)
For information on the anti-lock braking system (ABS), refer to
Hydraulic brakesin this chapter.
Driving with ABS
Maintain a steady brake pedal application; you do not need to pump or
remove your foot from the pedal. The ABS keeps the wheels rolling
during braking to maintain control and reduce stopping distances. For
information on the anti-lock braking system (ABS), refer toHydraulic
brakesin this chapter.
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.
Driving
116

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.
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.
PARKING
BRAKE
PULL TO
RELEASE
APPLY
PUSH TO
Driving
117

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.
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.
Driving
118

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.
When 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.
TRAILER
AIR SUPPLY
NOT FOR PARKING
PULL
TO
TOEVACUATE
PUSH
SUPPLY
PARKING
BRAKE
PULL
TOAPPLY
PUSH
TORELEASE
Driving
119

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.
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).
TRAILER
AIR SUPPLY
NOT FOR PARKING
PULL
TO
TOEVACUATE
PUSH
SUPPLY
Driving
120

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.
Exhaust brake (if equipped)
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:
²off-highway driving
²mountain driving
²heavy traffic
²high speed highway driving
It is not available with automatic transmissions.
The exhaust brake is a butterfly
type valve mounted in the exhaust
pipe. When the operator's foot is not
on the accelerator pedal and the
exhaust brake switch is in the ON
position, an air cylinder shuts the
butterfly valve, restricting the flow
of exhaust gases and retarding the
engine. This retarding action is
carried through the engine and drivetrain, slowing the vehicle and
reducing the need for frequent service brake applications.
Exhaust brakes are not intended for use as the primary braking system
during vehicle operation.
Driving
121