Abstract: There is disclosed a squirrel-cage motor for a winch drive or other application and control means for operating the motor in hoist or lower directions at any one of a plurality of speeds in either direction. The motor and winch are provided with a load brake. In one embodiment, the stator comprises two stator windings having different numbers of poles to provide high speed (fewer poles) and low speed (more poles) windings. The control means comprises a direct current power source, an alternating current power source, means for connecting the sources to the stator windings so that different speed points and braking operations are achieved, and means for operating the load brake. Low speed results from simultaneously energizing the low speed winding and the high speed winding from the alternating current power source and the direct current power source, respectively. Intermediate speed results from energizing only the low speed winding from the alternating current power source.

Abstract: A hoist uses an alternating current three-phase variable speed reversible wound rotor motor to hoist and lower a load. An electromechanical brake and a tachometer generator are connected to the motor shaft. Controllable SCRs connected to the motor stator (primary) windings control motor direction and speed and motor braking in response to error signals resulting from comparison of reference signals from an operator's master control and feedback signals from the tachometer. During hoisting and lowering (when the electromechanical brake is released), direct current voltage derived from appropriate gating of the controllable SCRs is applied to the motor stator (primary) winding to effect direct current braking as required. This direct current flow is smoothed and rendered more effective by gating "on" a free-wheeling SCR which is connected across two of the motor stator (primary) windings.