MCI SERVICE INFORMATION

Allison™ Transmission Retarder Operation

This tip is being written as an informational tool for the correct operation of Allison WTEC transmissions equipped with hydraulic retarders. When used properly, this feature assists in the deceleration of the coach which also reduces the wear of brakes/brake shoes.

The transmission retarder is enabled by a switch on the driver's console. When enabled, the transmission retarder is activated by two different methods; either with the application of the service brake pedal or by releasing the throttle pedal. A joystick on the driver's console selects the amount of retardation. Typically, retardation increases as the lever is moved to the rearmost position, but some coaches have been set up with maximum retardation in the foremost position, so refer to the decal next to the joystick for the specific retarder operation.

Inside the air brake valve are two switches that activate the retarder as the brake pedal is applied. Retardation increases with brake pedal travel.

For smooth operation and minimal heat generation, the suggested method of operation is initial application of the retarder in the lowest joystick position, and slowly moving the joystick towards the maximum retardation position as increased deceleration is required.

Additional information is available on Service Bulletin #2706.

If you need further assistance, please call the MCI Customer Support Center at (800) 241-2947.