Multi-stage transmission

A multi-stage transmission comprising:

• a drive gear shaft and a driven gear shaft disposed in parallel relative to each other;
• a plurality of drive gears and a plurality of driven gears supported on the drive gear shaft and the driven gear shaft, respectively, wherein the drive gears and the driven gears are constantly meshed with each other to constitute meshing gear combinations for different speeds;
• one of the drive gears and the driven gears are fixed to the gear shaft supporting the same, while the gear shaft supporting the other of the drive gears and the driven gears is a hollow gear shaft;
• and
• the other gears are supported on the hollow gear shaft individually in an engageable and disengageable manner through engaging means operated by gear shift driving means for gear shift;
• said engaging means comprises:
• engaging parts provided on an inner peripheral surface of each of the other gears at circumferentially spaced positions and having engaging surfaces in circumferential directions;
• engaging members provided in the hollow gear shaft and engageble respectively with the engaging parts of the other gears;
• and
• a plurality of parallel cam rods having sliding surfaces, respectively, in sliding contact with an inner peripheral surface of an inner hole of the hollow gear shaft so as to be movable in an axial direction of the hollow gear shaft, and being provided at axially spaced locations of the sliding surfaces thereof with a plurality of cam surfaces for acting on the engaging members, respectively, when moved axially;
• said gear shift driving means comprises:
• a control rod disposed axially slidably in the inner hole of the hollow gear shaft in sliding contact with the cam rods;
• and
• lost motion mechanisms interposed between the control rod and the plurality of cam rods and having therein respective springs acting axially of the control rod.