Operating Instructions, On-Highway Transmissions
Allison automatic transmissions are electronically controlled and provide five or six forward ranges and one Reverse (R) range. Typically, a T-handle shift control is used by the driver to select the ranges. See figure and figure .
For vehicles equipped with a transmission stalk switch, see 'Allison Transmission Multifunction Stalk Switch' for operating instructions.
Note: The following information describes the various transmission ranges. Some ranges are not available, depending on the series of transmission installed in the vehicle.
Fig. 1, T-Handle Shift Control (typical shifter)
Fig. 2, T-Handle Shift Control (optional shifter)
Park (P)
Use Park (P) when starting or shutting down the engine, to check vehicle accessories, and to operate the engine in idle for longer than 5 minutes. This position places the transmission in Neutral (N) and engages the park pawl.
Auto-Apply Parking Brake (PB)
The Auto-Apply Parking Brake (PB) places the vehicle in Neutral (N) and applies the parking brake.
Reverse (R)
Reverse (R) is used to back the vehicle. When the selector is in Reverse (R), the reverse warning signal will sound. Always bring the vehicle to a complete stop before shifting from a forward range to Reverse (R), or from Reverse (R) to a forward range.
Notice: Extended idling in Reverse (R) may cause transmission overheating and damage.
Do not idle in Reverse (R) for more than 5 minutes. Select Park (P), Auto-Apply Parking Brake (PB), or Neutral (N) when time at idle exceeds 5 minutes.
Note: The shift into Reverse (R) may not succeed if a range inhibitor is active. Check for illumination of the RANGE INHIBIT indicator.
Neutral (N)
The Neutral (N) position places the transmission in Neutral (N). This position is used when starting the engine and for stationary operation.
Warning: Failure to apply the vehicle parking brakes when the transmission is in neutral may allow the vehicle to move unexpectedly, possibly causing property damage or personal injury.
When Neutral (N) is selected, the vehicle service brakes, or parking brake must be applied. Selecting Neutral (N) does not apply vehicle brakes unless an auxiliary system to apply the parking brake is installed.
Warning: Do not coast in neutral. Coasting in neutral can cause an accident, possibly resulting in severe personal injury or death.
Do not let the vehicle coast in Neutral (N). If the vehicle is allowed to coast in Neutral (N), you could lose control of the vehicle.
Notice: Coasting in Neutral (N) can cause severe transmission damage.
Drive (D)
Warning: When going downhill, use a combination of downshifting, braking, and other retarding devices to control vehicle speed and the engine's rated governed speed. Failure to do so could reduce vehicle braking, possibly causing loss of vehicle control and resulting in personal injury or property damage.
In the Drive (D) position, the transmission will initially go into First (1) range when Drive (D) is selected. As vehicle speed increases, the transmission will upshift automatically through each available range up to Fourth (4) range or Fifth (5) range. As the vehicle slows, the transmission will downshift automatically.
When going downhill, downshift to a lower transmission range to increase engine braking and to help maintain control. The transmission has a feature to prevent automatic upshifting above the lower range selected. However, during downhill operation, the transmission may upshift to the next higher range, if the engine is exceeding its governed speed in the lower range.
Notice: Do not idle in Drive (D) for more than 5 minutes. Extended idling in Drive (D) may cause transmission overheating and damage. Always select Auto-Apply Parking Brake (PB) or Park (P) if time at idle is longer than 5 minutes.
Note: The shift into Drive (D) may not succeed if a range inhibitor is active. Check for illumination of the RANGE INHIBIT indicator.
Fourth and Third Ranges (4 and 3) [optional]
Use the Fourth (4) or Third (3) range for city traffic and for braking on steep downgrades.
Third and Second Ranges (3 and 2) [standard]
Use the Third (3) or Second (2) range for heavy city traffic and for braking on steeper downgrades.
First Range (1)
Use First (1) range when pulling through mud or deep snow, when maneuvering in tight spaces, or when driving up or down very steep grades. First (1) range provides the vehicle with its maximum driving torque and maximum engine braking effect.