OPERATION
5-46 / Driving the Vehicle
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5-27. 4x4 Transfer Case
5-27.1 4x4 Transfer Case (All Wheel Drive w/ Integral Transfer Case)
Some Pierce Custom Chassis with all wheel drive use a power-divider rear axle with integral transfer case. When
equipped with this type of system, torque to the front axle is delivered via a clutched differential.
The front drive axle can be engaged or disengaged while the vehicle is in motion.
To Engage Front Axle Drive
1. Reduce vehicle speed to less than 50 mph.
2. Ensure that rear wheels are not spinning faster than the front wheels and that the steering wheel is centered.
3. Remove foot pressure from the accelerator pedal and allow vehicle to coast.
4. Shift engagement switch.
5. Proceed with caution.
To Disengage Front Axle Drive
1. Remove foot pressure from the accelerator pedal and allow vehicle to coast.
2. Shift engagement switch.
3. Proceed with caution.
5-27.2 4x4 (All Wheel Drive) and Two-Speed Axle Combination
On certain chassis models a 4x4 option is offered in conjunction with a two-speed rear axle option. This configuration
is provided for those departments that require maximum grade climbing ability and 4x4 operation, while still desiring
normal highway speed capability. This configuration provides an interlock so that the 4x4 mode is available only
when the two-speed axle is in low range. Follow the same instructions for shifting into and out of 4x4 mode as
outlined above, but be sure that the two-speed axle is in low range.
Operation of the vehicle in all wheel drive mode increases the wear on the driveline components, tires,
and axles. Avoid engaging the front axle drive except in slippery or off-road conditions, or premature
component wear may result.
Use extreme caution when backing up a steep grade while the front drive axle is engaged. Weight
transfer from the rear axle to the front axle can cause overloading of the front drive gear and
component damage may result.
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