Transmission with range engagement assurance

Abstract

An auxiliary transmission module has an auxiliary transmission having an input shaft, an output shaft, and a mechanical synchronizer, and a controller. The controller is configured to command a downshift for the auxiliary transmission, control the input shaft to a generally synchronous speed with the output shaft for engagement, and increment the speed of the input shaft by a predetermined speed differential above the speed of the output shaft or engagement if the auxiliary transmission is unengaged after controlling to the generally synchronous speed. A method of downshifting includes commanding a downshift for the auxiliary transmission, controlling an input shaft to a generally synchronous speed with an output shaft for engagement, comparing a rotational speed upstream with a rotational speed downstream to verify engagement, and controlling the input shaft to an asynchronous speed with the output shaft for engagement during a recycle event when it is unverified.

Dependencies are inferred from the claim text.