When operating the PTO unit with the vehicle stationary, first set the
parking brake (chock the wheels if the vehicle is on a hill or other
unlevel surface).
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.
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.
Driving
102
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.
Driving
103
4 and 2 (Fourth 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. Use this position when pulling through mud or
snow, driving up steep grades, hauling extra heavy loads or where
maximum reduction is required.
Allison 2400 series
This transmission provides four ranges and one reverse range.
P (Park)
Use this position when you start the engine. The engine is designed to
start in the P (Park) or N (Neutral) position only.
Always come to a complete stop before shifting into P (Park). Make sure
the gearshift is securely latched in P (Park). This position locks the
transmission and prevents the rear wheels from turning.
Always set the parking brake fully and make sure the gearshift
lever is latched in P (Park). Turn off the ignition whenever you
leave your vehicle.
When parking on hilly or off-road terrains, be sure to set the parking
brake fully and chock the wheels to prevent unexpected and possibly
sudden vehicle movement.
R (Reverse)
Use this position to move the vehicle backwards. Completely stop the
vehicle before shifting from a forward gear (1, 2, 4 or D) to R (Reverse),
or from R (Reverse) to any forward gear. The reverse warning signal will
sound when the selector is in R (Reverse). Reverse has only one gear
and provides the greatest gear reduction.
Driving
108
N (Neutral)
This position can be used when starting the engine. The engine is
designed to start in the P (Park) or N (Neutral) position only. The
engine should be at idle speed when any shift from N (Neutral) to a
drive range is made.
The N (Neutral) position may also be used during stationary operation of
the Power Take-Off (PTO), if equipped.
Do not allow your vehicle to coast in N (Neutral). Engine
braking is not available in N (Neutral). Allowing your vehicle to
coast in N (Neutral) may result in loss of vehicle control and severe
internal transmission damage.
D (Drive—Normal driving position)
In this position, the transmission starts in first gear and automatically
shifts through second, third and fourth depending on load and speed
demands. When the vehicle is slowing down, the transmission will
automatically downshift. This range is used for highway driving under
normal conditions.
4 and 2 (Fourth and Second)
Use this position when road, load or traffic conditions make it desirable
to restrict the automatic shifting to a lower range. These ranges provide
greater engine braking than D (Drive). When conditions 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. Use this position when pulling through mud or
snow, driving up steep grades, hauling extra heavy loads or where
maximum reduction is required.
Power take-off (PTO) operation with an Allison automatic
transmission (except MD applications and vehicles equipped with
a Caterpillar 3126E engine)
The power take-off can be operated while the vehicle is standing or
moving.
To engage the PTO, apply the brakes and shift to any gear other than N
(Neutral) - this stops the rotation of the PTO drive gear in the
transmission - then engage the PTO.
Driving
109
WRECKER TOWING
Always unload your vehicle before towing it. The recommended method
of towing is with the drive wheels off the ground.
Before towing, make sure:
•the parking brake is released.
•if air pressure has been lost, to release the brakes manually.
Improper towing of the vehicle will not allow sufficient lubrication of the
transmission which may cause serious damage to internal transmission
components. Always follow the outlined towing procedures.
•To tow a vehicle on the front wheels,the steering wheel must be
in the straight ahead position. Secure the steering wheel with a
holding device (such as provided by a towing company).
•To tow a vehicle on the rear wheels,it will be necessary to remove
the drive axles or disconnect the driveshaft. If the drive axles are
removed, the ends of the axle housing must be sealed to prevent the
loss of axle lubricant during towing.
•To tow a vehicle with an inoperative rear axle,the rear wheels
must be raised onto a dolly or tow the vehicle on the front wheels.
•If your vehicle is equipped with tow hooks,chains must be
fastened directly to the tow hooks on the vehicle.
•If your vehicle is not equipped with tow hooks,chains must be
routed under the bottom edge of the bumper with a protection bar to
protect the bumper, and attached to the vehicle chassis. Under no
circumstances is the vehicle to be lifted or towed by attaching chains
directly to the bumper.
RAISING THE VEHICLE
Never lift the vehicle by the bumper. When raising the vehicle, attach
chains to or place the jack(s) directly beneath the main structural
members of the vehicle.
PUSH-STARTING YOUR VEHICLE
Avoid attempting to start a vehicle by pushing. Instead, use jumper
cables as described underJump starting your vehiclein theRoadside
emergencieschapter. Vehicles with an automatic transmission cannot be
started by pushing.
Roadside emergencies
125
CHECKING UNDER THE HOOD
Opening the hood
The hood and fenders are held in position by a latch located on each
fender.
The parking brake must be fully set before opening the hood or
possible personal injury may occur.
If you must leave the engine running while checking under the
hood, do not allow any loose clothing, jewelry, hair or other
items to get near moving engine components or possible personal
injury may occur.
To open the hood:
1. Set the parking brake, shift into N (Neutral) (automatic transmission)
or 1 (First) (manual transmission) and turn the engine off.
2. Lift upward on the bottom of
each latch.
3. Pull the bottom of each latch
away from the fender.
Maintenance and care
126
1. Start the engine and let it run until it reaches normal operating
temperature (the engine coolant temperature gauge indicator will be
near the center of the normal area between H and C).
2. Park the vehicle on level ground.
3. Set the parking brake and shift into N (Neutral) (automatic
transmission) or 1 (First) (manual transmission).
4. Turn off the engine and wait a few minutes for the oil to drain
completely into the oil pan.
5. Open the hood. Protect yourself from engine heat.
6. Locate and carefully remove the
engine oil level indicator (dipstick).
7. Wipe the indicator clean. Insert the indicator fully, then remove it
again.
•If the oil level isbetween FULL and OPERATING RANGE,the oil
level is acceptable.DO NOT ADD OIL.
•Maintain the oil level between ADD and OPERATING RANGE on the
dipstick by adding oil as required.
•The distance from ADD to OPERATING RANGE on the dipstick
represents 1.9L (2 quarts).
•Oil levels above OPERATING RANGE may cause engine damage. Some
oil must be removed from the engine by a qualified service technician.
8. Put the indicator back into the engine and ensure it is fully seated.
Maintenance and care
128
Adding and replacing engine coolant-Caterpillar 3126 B engine
Refer to the engine operator’s manual for engine cooling system
information.
FAN CLUTCHES
Your vehicle’s cooling system is equipped with a viscous variable speed
fan clutch.
•The fan clutch helps control cooling, increase performance, improve
fuel economy and reduce noise.
•The fan clutch is controlled by bimetallic spring sensors. Do not
tamper with these sensors as this may change their calibration or keep
the fan clutch from operating at all.
Stay clear of the fan/fan area while the engine is running or
possible personal injury may occur.
CHECKING AND ADDING POWER STEERING FLUID
Checking power steering fluid level
Check the power steering fluid level using the following procedure. Refer
to the Scheduled Maintenance Guide for the recommended service
intervals. If adding fluid is necessary, use only MERCONAT F.
1. Set the parking brake, shift into N
(Neutral) (automatic transmission)
or 1 (First) (manual transmission)
and turn the engine off.
2. Open the hood.
3. Clean the top of the power
steering fluid reservoir.
4. Remove the dipstick from the
reservoir and wipe the dipstick
clean.
5. Reinstall the dipstick. Remove it again and check the fluid level.
Maintenance and care
136