Change speed transmissions and controls therefor

Claim 1

A change speed transmission providing a finite plurality of speed ratios, said transmission comprising drive means adapted to drivingly engage said speed ratios, a rotatable shaft with a surface, said drive means slidable on said shaft, cam means including two cam tracks on the surface of said shaft between said shaft and said drive means to engage selectively said drive means, indexing means operable and mounted on said shaft to move said cam means, one of said cam tracks comprising a zigzag form and the other of said cam tracks comprising two substantially parallel linear portions interconnected by a linear and curved portion, and in which a first drive means is associated with said one cam track and a second drive means is associated with said other cam track, the arrangement being such that rotation of said shaft firstly axially moves said first drive means in a first axial direction and maintains said second drive means axially stationary, secondly reverses the direction of movement of said first drive means and, moves said second drive means in an axial direction, and thirdly moves said first drive means axially in said first direction and maintains said second drive means axially stationary, and a manually operable control for indexing movement of said indexing means by successive movement for selection of alternate ratios which are zero speed ratios.