2021 FORD F650/750 Owners Manual

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.
HILL START ASSIST WARNING: The system does not
replace the parking brake. When you
leave your vehicle, always apply the
parking brake. WARNING:
You must remain in
your vehicle when the system turns on.
At all times, you are responsible for
controlling your vehicle, supervising the
system and intervening, if required.
Failure to take care may result in the loss
of control of your vehicle, serious
personal injury or death. WARNING:
The system will turn
off if a malfunction is apparent or if you
rev the engine excessively. Failure to take
care may result in the loss of control of
your vehicle, serious personal injury or
death.
The system makes it easier to pull away
when your vehicle is on a slope without the
need to use the parking brake.
When the system is active, your vehicle
remains stationary on the slope for two to
three seconds after you release the brake
pedal. This allows time to move your foot
from the brake to the accelerator pedal.
The system releases the brakes
automatically once the engine has developed sufficient torque to prevent your
vehicle from rolling down the slope. This
is an advantage when pulling away on a
slope, for example from a car park ramp,
traffic lights or when reversing uphill into
a parking space.
The system activates on any slope that
causes your vehicle to roll.
Note:
There is no warning light to indicate
the system is either on or off.
Using Hill Start Assist
1. Press the brake pedal to bring your vehicle to a complete standstill. Keep
the brake pedal pressed and shift into
first gear when facing uphill or reverse
(R) when facing downhill.
2. If the sensors detect that your vehicle is on a slope, the system activates
automatically.
3. When you remove your foot from the brake pedal, your vehicle remains on
the slope without rolling away for
about two to three seconds. This hold
time automatically extends if you are
in the process of driving off.
4. Drive off in the normal manner. The system releases the brakes
automatically.
Note: When you remove your foot from the
brake pedal and press the pedal again when
the system is active, you will experience
significantly reduced brake pedal travel. This
is normal.
Switching the System On and Off
Vehicles with Manual Transmission
You can switch this feature on or off in the
information display. The system
remembers the last setting when you start
your vehicle.
134
F650750 (TBC) , enUSA, Edition date: 202010, Second-Printing Brakes

Vehicles with Automatic Transmission
You cannot turn the system on or off.
When you switch the ignition on, the
system automatically turns on.
AIR BRAKES (IF EQUIPPED)
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. WARNING:
Do not move the
vehicle when the air pressure is
insufficient because the brake system
may be inoperative.
After starting the engine, give the air
compressor time to build up the air
pressure to
60 psi (414 kPa) before moving
your vehicle. Periodically check the air pressure gauge
while driving. Pressure should range
between approximately 100 psi (690 kPa)
to
130 psi (896 kPa). The air compressor
governor cut-in and cutout 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 may happen because
excessive brake applications are depleting
the system air pressure. If this condition
occurs, stop driving your vehicle until the
compressor has fully recharged the air
system.
Select a gear ratio to help slow your vehicle
before descending grades. Supplementing
with brakes, as required, help to safely slow
the vehicle and avoids 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 painted orange indicator is on
the air chamber push rod at the slack
adjuster stroke dimension that requires
service when visible during brake
application.
A qualified service technician should
perform air brake inspection and
adjustment or repairs keeping to the
instructions in the service manual.
135
F650750 (TBC) , enUSA, Edition date: 202010, Second-Printing BrakesE210336 E206772

Cam Brakes - Automatic Slack
Adjusters
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. Standard air brakes (cam) are equipped
with automatic brake adjusters. Automatic
adjustment occurs during brake
applications. Inspect brakes for proper
adjustment at the specified intervals. See
Scheduled Maintenance (page 319).
Emergency Air Brake 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. 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. The brake pedal
controls all these systems in the same
manner as for normal stops.
EXHAUST BRAKE
(IF EQUIPPED)
WARNING:
Do not use tow/haul
when the road surface is slippery. Failure
to follow this instruction could result in
the loss of control of your vehicle. WARNING:
Do not use diesel
engine exhaust braking when the road
surface is slippery. Failure to follow this
instruction could result in the loss of
control of your vehicle.
Note: Installing an exhaust or auxiliary
brake does not necessarily protect the
engine from exceeding the maximum
governed speed. Use the primary brakes to
make sure the engine never exceeds the
maximum governed speed under any
circumstance.
Note: Before starting the engine, make sure
that the exhaust brake is off. Do not switch
the exhaust brake on until the engine has
reached normal operating temperature.
Note: Engine speed has a major influence
on limiting performance. When engine
speed stays at the maximum allowable
level, the exhaust brake operates at peak
performance.
Note: Exhaust brakes operate effectively
with automatic transmissions. However,
performance varies with engine speed and
the gear selected by the transmission.
136
F650750 (TBC) , enUSA, Edition date: 202010, Second-Printing BrakesE210337

An exhaust brake is an auxiliary braking
system that assists, but does not replace,
the primary brake system. It helps control
vehicle speed. It is not a vehicle-stopping
device.
Use the button on the instrument panel, in
combination with the accelerator pedal,
to maximize the use of the exhaust brake
in the following conditions:
•
Off-highway driving.
• Mountain driving.
• Heavy traffic.
• High-speed highway driving. To switch the exhaust brake on, press the
button. A light on the instrument cluster
indicates the system is on. Press the button
again to switch it off.
While approaching a steep grade, make
sure that the exhaust brake switch is on.
The exhaust brake begins working as soon
as you remove your foot from the
accelerator pedal. Before descending a hill or steep grade,
always select the proper gear. If you take
the transmission out of gear while
descending, you may not be able to select
another gear because of maximum
governed RPM.
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 driving down a 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.
Exhaust Brake Operating
Characteristics
The exhaust brake switches on when you
remove your feet from the accelerator
pedal and the exhaust brake is on.
If the brake is working properly, you may
notice:
•
A slight change in engine sound when
the exhaust brake turns on.
• A smooth braking effect. Do not expect
a retarding effect similar to sudden,
hard application of the service brakes.
• A retarding force possibly felt acting
against your body during brake
application, depending on the grade
and vehicle load. This force helps your
vehicle resist increasing speeds down
grades.
• Engine temperatures remaining in the
normal operating range.
137
F650750 (TBC) , enUSA, Edition date: 202010, Second-Printing BrakesE215226

•
A drop in engine RPM, depending on
grade and vehicle load, during a
descent.
• A decrease in road speed when
applying the exhaust brake during a
descent, except when your vehicle is
carrying a heavy load or the grade is
extremely steep. In these instances,
you may need to apply the service
brakes occasionally.
TRAILER BRAKES
Trailer Brake Hand Control (If Equipped) 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 is located on the
right-hand side of the instrument panel. It
applies the trailer service brakes, which are
independent of the truck or tractor service
brakes.
It operates a valve that provides gradual
control of air pressure applied. When the
valve is only partially applied, you can
override the trailer brakes by pressing fully
on the brake pedal. To apply the trailer brakes using the hand
control, move the lever downward. The
further you push the lever 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 decreases to approximately 35 psi
(249 kPa)
.
The parking brake controls the spring
brakes on the tractor. When you pull the
knob out, it causes the trailer supply valve
to pop out, applying both the tractor and
trailer parking brakes. You can
independently release the trailer brakes by
pushing only the trailer air supply valve in.
138
F650750 (TBC) , enUSA, Edition date: 202010, Second-Printing BrakesE210339 E210340
A
B
12
A320
A E210341

Initial Charge
With the air system completely discharged,
both knobs (A and B) are out. When the
air pressure reaches 70 psi (481 kPa), the
trailer air supply (A - red knob) may be
pushed in and should stay in, charging the
trailer air system and releasing the trailer
brakes. You can push in the parking brake (B -
yellow knob) and supply air to the tractor
spring brakes, releasing them.
Normal Driving Position
Push in both knobs (A and B) to supply air
to both trailer and tractor spring brakes,
releasing all brakes.
139
F650750 (TBC) , enUSA, Edition date: 202010, Second-Printing BrakesE210342 E210343 E210343

System Park
With both knobs (A and B) pushed in
(normal driving position), the parking
brakes for both the tractor and trailer can
be applied by pulling the parking brake
knob (B) 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 (A and B) 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.
140
F650750 (TBC) , enUSA, Edition date: 202010, Second-Printing BrakesE210344 E210342

Automatic Application
If both knobs (A and B) 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).
Actuation of Trailer Park (Emergency)
or Tractor Bobtail Position To actuate the trailer brakes only, pull out
the trailer air supply (A) knob. 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.
141
F650750 (TBC) , enUSA, Edition date: 202010, Second-Printing BrakesE210345 E210345