Gears on sleeves have a hub (4) with teeth that are matched to a sliding collar (5) and a shaft hub (6), which is splined to the shaft. Splined to a rotating gear, a gear on a sleeve will also turn, spinning freely on its sleeve until the sliding collar engages (7) both the gear hub and shaft hub. The collar engages the driven gear by means of a shifting fork (not shown) which fits into the groove (8) on the outside of the collar.