Shift control system for an auxiliary section of a compound vehicular transmission

Abstract

A method and apparatus for operating a compound transmission automatically prevents a manually selected shift of the auxiliary section from occurring unless the vehicle speed is within a predetermined maximum limit or range. A shift controller initially determines if a request for a shift operation in the auxiliary section has been made by the operator of the vehicle. This determination may be inferred from a change in the position of a manually operable switch. If a shift request has been made, the shift controller determines if the main section of the transmission is in the neutral gear ratio. If the main section of the transmission is not in the neutral gear ratio, then the shift controller takes no further action. When the shift controller determines that the main section of the transmission is in the neutral gear ratio, then it determines if the speed of the vehicle is within a predetermined limit or range to enable shifting of the auxiliary section in a safe and efficient manner. If the vehicle speed is not within the predetermined limit or range, then the shift controller takes no further action. If, however, the vehicle speed is within the predetermined limit or range, the shift controller activates a shift actuator to effect the desired shift within the auxiliary section of the transmission.

Dependencies are inferred from the claim text.