Abstract: A variety of shifter mechanisms are provided for controlling the axial distance between half-pulleys of a split pulley variable transmission, thus controlling the transmission ratio of the variable transmission. Some of these embodiments include a differential such that a variable transmission can be driven and shifted differentially by two inputs. A torque or rotation difference between the inputs results in a change in the transmission ratio and in-common torque or rotation is transmitted through the transmission to an output. The same motors used to drive the output of the transmission are thus also able to effect shifts in the transmission ratio. Accordingly, motor mass that is not being used to effect high-speed shifts may be used to drive the transmission output, and vice versa. The provided shifter embodiments are well-suited to application to nested-pulley variable transmissions, including nested-pulley infinitely variable transmissions.

Abstract: A continuously variable belt drive system including a driving pulley assembly, a driven pulley assembly, and a V-shaped belt engaged to transfer rotary power therebetween is disclosed herein. The driving pulley assembly includes an idler pulley portion. As the belt speed decreases, the belt migrates downward within the driving pulley assembly until it falls within the idler pulley portions, thereby isolating the belt from the rotation of the driving pulley assembly. The driving pulley assembly also includes a belt tensioning mechanism that maintains proper belt tension at all speeds and drive ratios. The tensioning mechanism relies upon a pivotably mounted centrifugal weight arm to provide tensioning as a function of speed. A compression spring provides axial pressure to maintain belt tension over all drive ratios. The spring, acts against a curved cam edge on a pivoting lever arm, which arm transfers an axial force to the rear sheave of the driven pulley assembly.

Abstract: An adjustable sheave including at least one pair of annular belt grooves defining annular discoidal flange members relatively movable on an end threaded hub support through an annular adjusting ring threadedly mounted on the threaded hub support end, the adjusting ring including locking means cooperable with one of the pair of flange members to tighten and bind the threads of the adjusting ring to the engaged threads of the hub support end.