Abstract: A transmission, in which power is transmitted from one variable diameter pulley to another through an endless band, has an automatic band tensioning mechanism. The band tensioning mechanism includes a tensioning shaft, an adjusting wheel rotatably mounted on the shaft, and a spring connected between the shaft and the wheel. A worm engaged with the wheel is mounted on a shaft slidably received in a locking member. The worm has a locking shoulder at one end which is normally urged, by the spring acting through the wheel, into engagement with a locking shoulder on one end of the locking member. The worm is moved out of locking engagement against the bias of the spring for rotation of the worm and wheel, and tightening of the spring.

Abstract: An auxiliary speed reducer unit can be detachably mounted upon a main speed reducer unit to form a compound speed reducer. The main unit includes a housing and a worm shaft rotatably journalled therein with an end portion of the worm shaft extending from the housing. The auxiliary unit has a housing with an opening therein for receiving the end portion of the main unit worm shaft. An input worm shaft is rotatably journalled within the auxiliary housing and has a worm thereon that meshes with a worm gear. Within the worm gear is a central bore of a size to receive and key with the end portion of the main unit worm shaft. Annular grooves on opposite faces of the worm gear receive annular projections having a radial width less than said grooves. The projections extend from opposite sides of the auxiliary unit housing to support the worm gear in a loosely rotatable manner for limited play in the plane of the gear while the gear is in mesh with the input worm.