Abstract: This scaffold hoist uses a transmission mechanism whose output shafts are fastened to the hoist housing, and whose case rotates, carrying a sheave which impels the mechanism along the cable. The transmission mechanism is advantageously a quadrant drive for extremely high torque-to-weight ratio.The sheave has a peripheral groove, tapered and deep enough to seat a cable having any of three different diameters, at different depths in the groove.The cable wraps around three-quarters of the sheave. Around five-eighths of the sheave, a chain presses the cable into the groove. The chain rollers enter the groove deeply enough to engage even the smallest-diameter cables of interest, while clearing the sheave periphery. The chain side bars ride along the sides of the sheave, holding the chain and cable in position.A resettable overspeed brake uses a rotary cam that jams a cable of any of the three sizes, at correspondingly various cam angles.

Abstract: An improved cable hoist apparatus having a drive sheave, a tensioning sheave, a pressure inducing chain and a brake system including a set of gears, linkage and brake actuating means. The linkage includes means for disengaging the gears under extreme operating conditions without loosening the chain from around the cable. An improved shaft assembly prevents binding and a solenoid actuated primary brake is manually operated.