A cable derailment responsive apparatus for use in terminating the operation of a cable drive for a chairlift, ski lift, gondola or the like is disclosed. The apparatus includes a spring biasing a portion of the pulley assembly for movement if the cable jumps the sheaves, further includes an electrical circuit having a plug-in connector that is mechanically pulled apart from the remainder of the circuit upon cable derailment to interrupt or deactivate the cable drive. Upon remounting of the cable on the sheave assemblies, the connector can be plugged back into the circuit to permit driving of the cable.