EXHAUST BRAKE (IF EQUIPPED)
An exhaust brake is an auxiliary braking system that assists, but does
not replace, the primary service brake system. It is intended to help
control vehicle speed; it is not a vehicle stopping device.
A switch on the instrument panel, in
combination with the accelerator
and clutch pedal, 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
To operate the brake, push the switch up to turn it on. Push the switch
down to turn it off.
Note:Before starting the engine, make sure that the exhaust brake
switch is pushed down to the off position. Do not turn the exhaust brake
on until the engine has reached normal operating temperature.
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.
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 can’t select another gear because of maximum RPM being governed.
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 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 use to ascend the hill.
Note:Engine speed has a major influence of retarding performance.
When engine speed is maintained at the maximum allowable level, the
exhaust brake operates at peak performance.
Note:Maximum exhaust brake performance is related to the type of
transmission your vehicle is equipped with.
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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 (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.
ANTI-LOCK BRAKE SYSTEM (ABS)
Your vehicle is equipped with an anti-lock braking system (ABS). This
system helps you maintain steering control during emergency stops by
keeping the brakes from locking. Noise from the ABS pump motor and
brake pedal pulsation may be observed during ABS braking; any
pulsation or mechanical noise you may feel or hear is normal.
When hard braking is required, apply continuous force on the brake
pedal. Do not pump the brake pedal since this reduces the effectiveness
of the ABS and increases your vehicle’s stopping distance. The ABS
activates immediately, allowing you to retain steering control during hard
braking and on slippery surfaces. However, the ABS does not decrease
stopping distance.
ABS warning light
The
light in the instrument cluster momentarily illuminates when the
ignition is turned on. If the light does not illuminate during start up,
remains on after the vehicle reaches 5–10 mph (8–16 km/h), or flashes,
the ABS may be disabled and may need to be serviced.
Even when the ABS is disabled, normal braking is still effective. If
the
light illuminates with the parking brake released, have your
brake system serviced immediately.
1
2
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several transmission upshifts and downshifts; during this learning
process, slightly firmer shifts may occur. After this learning process,
normal shift feel and shift scheduling will resume.
P (Park)
This position locks the transmission and prevents the rear wheels from
turning.
To put your vehicle in gear:
1. Start the engine
2. Press the brake pedal
3. Move the gearshift lever into the desired gear
To put your vehicle in P (Park):
1. Come to a complete stop
2. Move the gearshift lever and securely latch it in P (Park)
WARNING:Always set the parking brake fully and make sure
the gearshift is latched in P (Park). Turn the ignition to the off
position and remove the key whenever you leave your vehicle.
R (Reverse)
With the gearshift lever in R (Reverse), the vehicle will move backward.
Always come to a complete stop before shifting into and out of R
(Reverse).
N (Neutral)
With the gearshift lever in N (Neutral), the vehicle can be started and is
free to roll. Hold the brake pedal down while in this position.
D (Drive)
This is the normal driving position for the best fuel economy. This
position allows automatic upshifts and downshifts through gears one
through six.
4 (Fourth)
This position allows automatic upshifts and downshifts in gears one
through four.
2 (Second)
Use 2 (Second) to start-up on slippery roads or to provide additional
engine braking on downgrades.
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Allison 2500
This transmission is available with a column-mounted gearshift lever. The
gear positions are displayed on the RNDL in the instrument cluster.
WARNING: To avoid sudden, unexpected vehicle
movement and possible personal injury or death:
1. Bring the vehicle to a complete stop.
2. Shift the transmission into N (Neutral).
3. Apply the parking brake and make sure it is holding properly.
4. Turn the engine off when you leave the vehicle.Never leave the
vehicle unattended when the engine is running.
Transmission fluid operating temperatures - 2200/2500 models
Allison 2200 and 2500 models:The sump/fluid reservoir temperatures
should not exceed 250°F (120°C). The converter temperature should not
exceed 300°F (144°C). he sump/fluid reservoir temperature should not
exceed 250 F (120 C).
TorqShift6-Speed models:The sump/fluid reservoir temperatures
should not exceed 250°F (120°C).
Allison 3000 series
The Allison 3000 Series offers two shift modes: Performance and
Economy. Performance Mode gives the best all-around transmission
operation; Economy Mode provides operation at lower engine RPM while
maintaining adequate performance. The transmission defaults to
Performance Mode when you start the engine. Pressing MODE on the
shifter activates Economy Mode and illuminates the Mode ON lamp.
If the engine speed is above idle when a gear is selected using the
shifter, the vehicle won’t move; the shifter must be moved to re-select a
gear after the engine speed returns to idle.
Note:For more information regarding the Allison 3000 Series, refer to
the separateAllison 3000 Series Operator’s Manual.
Torque lock
If your vehicle is parked on an incline and P (Park) is not properly
engaged (the parking brake is not applied before the transmission is
shifted into P [Park]), the weight of the vehicle may generate an
excessive amount of torque on the parking pawl, making it difficult to
shift the transmission out of P (Park). Hold the brake pedal down while
shifting out of P (Park), then release the parking brake.
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Engaging the clutch
•Always start in the proper gear.An empty vehicle can start in a
higher gear than a fully loaded vehicle. Starting in too high a gear can
cause clutch slippage and excessive heat and wear on the clutch. A
gear that starts the vehicle moving at idle speed is the correct gear. If
the engine has to be revved to get the vehicle going, the gear
selection is too high.
•Do not shift until the vehicle has reached the proper speed.
Upshifting before the vehicle has reached the proper speed can cause
clutch slippage and excessive heat and wear on the clutch.
•Never hold a vehicle on a grade with the clutch.This causes the
clutch to slip and can actually burn up the clutch.
•Never coast with the clutch disengaged.The high RPM
(sometimes over 10,000), can actually burst the facing material of the
clutch.
•Never engage the clutch while coasting.Re-engaging the clutch
after coasting may not only cause a great shock to the clutch, but the
whole drivetrain. Internal engine damage and/or clutch and flywheel
failure can result from this.
If the transmission is equipped with a ceramic clutch, you must start the
vehicle moving in first gear and engage the clutch before pressing the
accelerator at idle. Also, don’t try to slip the clutch by raising engine
RPM and riding or feathering the clutch pedal since this causes erratic
engagement which can cause engine stalling and potential serious
damage to driveline components.
Clutch brake (non-synchronized transmissions) - Vehicle stationary
A clutch brake is used to stop transmission input shaft rotation so that
the initial 1 (First) or R (Reverse) gear selection can be accomplished
when the vehicle is stationary and the engine is at idle speed. Clutch
brake application occurs in the last inch (25 mm) of clutch pedal travel.
When using the clutch brake, fully press the clutch pedal and shift the
transmission into 1 (First) or R (Reverse). If the transmission won’t go
into one of these gears, slowly release the clutch pedal while applying
light pressure on the transmission shift lever until it shifts into gear.
Note:After engagement of 1 (First) gear,do notuse the clutch brake
for upshifting or downshifting. If you do, clutch brake life shortens and
gear selection shift efforts may increase.
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WARNING:Do not coast the vehicle with the clutch pedal
pressed or with the transmission in neutral. This practice could
result in loss of vehicle control.
To go forward
With the engine idling, press the clutch pedal in and shift into 1 (First).
Engage the clutch while pressing the accelerator to start forward.
Operate the clutch and upshift as required by driving conditions.
To go backward
Put the gearshift lever in R (Reverse) and engaging the clutch while
pressing lightly on the accelerator.
Shifting with a synchronized transmission
With the clutch pedal pressed in, use the 2 (Second) gear synchronizer
to stop the clutch disc rotation; this allows smooth engagement of 1
(First) or R (Reverse). To complete the gear engagement, it may be
necessary to apply light pressure to the gearshift lever during initial
engagement of the clutch. It takes a second or two to match gear speeds;
steady pressure on the gearshift lever helps the synchronizer perform its
job more quickly. If the gearshift lever is forced into position, this action
defeats the purpose of the synchronizer by causing gear clash.
Shifting with a non-synchronized transmission
Refer toClutch brakeandDouble clutch proceduresin theClutch
section of this chapter.
Operating the Eaton FS-5205A 5–speed transmission
This transmission is equipped with
five forward gears and one reverse;
gears 2–5 are synchronized. The
shift pattern is embossed on the
gear shift knob.
Do not shift the transmission into R (Reverse) while the vehicle is
moving as this could damage the transmission.
R 2 4
3 5 1
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Care should be taken to avoid sudden accelerations when both drive
wheels are on a slippery surface.
WARNING:Sudden accelerations on slippery surfaces could
cause the wheels to spin, the vehicle to turn sideways on a
crowned road surface or in a turn, possibly resulting in loss of vehicle
control and personal injury.
Some drive axles have a driver-controlled differential lock. The
differential lock can lock or unlock the differential when the vehicle is
moving or stopped. When extra traction is required, the differential lock
provides full power to both axles.
When the differential is locked, the vehicle’s turning radius increases
(vehicle “under-steers”).
The differential can be locked or unlocked when the vehicle is moving at
a constant speed of under 25 mph (40 km/h) and while the wheels are
not slipping. The differential must not be locked when the vehicle is
traveling down steep grades and traction is minimal.
Note:Never use the differential lock at vehicle speeds above 25 mph
(40 km/h).
The differential lock and differential lock light automatically disengage at
speeds above 25 mph (40 km/h). The differential lock remains off until
either the vehicle is restarted or the differential lock switch is turned off
then back on.
Axle conversions
It is not recommended, or approved, for axle conversions to be
performed. However, it is understood that, on occasion, aftermarket
add-on axles are installed by others on the truck chassis which allow
operator control for weight transfer from other axles (i.e., air lift axles).
WARNING:When operating a loaded vehicle, the driver must
keep all adjustable axles on the ground at all times, supporting
their share of the vehicle’s load. Failure to do so can overload other
axles, tires, wheels, springs, steering components, brakes and frames,
resulting in early component failure, loss of vehicle control, possible
property damage and personal injury.
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To shift the axle from LOW to HIGH with the vehicle moving, accelerate
to approximately 35 mph (56 km/h), press the lower part of the switch
while the transmission is in N (Neutral), then release and apply the
accelerator.
To shift the axle from HIGH to LOW with the vehicle stopped, place the
transmission in N (Neutral), then press the upper part of the switch.
Note:Do not shift the axle to LOW with the vehicle in motion.
Split-shifting (combined axle and transmission shift - manual
transmissions only)
Split-shift sequence
Ratio combination1234567891011
Transmission gear 1st 1st 2nd 2nd 3rd 3rd 4th 4th 5th 6th 6th
Axle range LO HI LO HI LO HI LO HI LO LO HI
To downshiftthe axle to a slower ratio and shift the transmission, shift
the transmission and move the switch to the lower ratio before the
clutch is re-engaged.
To upshiftthe axle and shift the transmission, move the switch to a
faster ratio and make the transmission shift in the usual manner.
Ratio extender use
Low end:A two-speed axle can be used as a ratio-extender when
split-shifting is not necessary. For low end use, just shift the axle into
LOW to start out, and shift to HIGH when the extra torque is no longer
needed.
Transmission (5-speed) 1st 1st 2nd 3rd 4th 5th 6th
Two-speed axle Axle low Axle high
High end:To use the two-speed axle as a high end ratio-extender, stay
in the LOW range for normal upshifts and only shift the axle to HIGH on
the freeway for greater road speed.
Transmission (5-speed) 1st 2nd 3rd 4th 5th 6th
Two-speed axle Low for gradeability Axle high
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