The retarder is at the output of the transmission and consists of a vaned cavity and a vaned rotor which is splined to and driven by the output shaft. When the retarder is activated, fluid is directed into the retarder cavity. The interaction of the fluid with the rotating and stationary vanes causes the retarder rotor speed, and the output shaft, to decrease and slow the vehicle.

When the retarder is deactivated, the retarder cavity is evacuated.

Additional retarder information can be obtained by ordering our free Motor Home video, "Operating the Allison MH Series Transmission" (VI3424EN). Click on this link for ordering details.

Motor Home Video