Interlock assembly for vehicle transmission

Abstract

An interlock assembly for a vehicle transmission prevents more than one of a plurality of shift rails from being simultaneously moved axially out of a central neutral position to a gear engaging position. The interlock assembly includes an interlock plate having four semi-circular cut-outs (one for each of the shift rails) and two relative large interior openings. The interlock assembly further includes a backing plate which is somewhat smaller than the interlock plate and has two relatively small interior openings. A pair of threaded fasteners extend through the small openings of the backing plate and through respective spacer bushings disposed in the large interior openings of the interlock plate into threaded engagement with the housing of the hydraulic actuator. The spacer bushings prevent the interlock plate from being frictionally engaged between the backing plate and the housing of the hydraulic actuator. As a result, the interlock plate is loosely supported on the threaded fasteners and can slide freely in any direction relative thereto. Each of the four cut-outs of the interlock plate is formed having opposed tapered edges which cooperate with tapered grooves formed on the exterior surfaces of the four shift rails. When any one of the four shift rails is moved out of the central neutral position, the interlock plate slides to extend into the grooves of the other three shift rails. Thus, the interlock plate prevents the other shift rails from moving until all are in the central neutral position.