Overload protection apparatus for hoisting machine

摘要

The disclosure relates to an overload protection apparatus for hoisting machines such as rope hoists or chain blocks. One gear incorporated in the reduction gear train of the hoisting machine is composed of an outer and an inner gear units between which torque is transmitted through resilient means acting therebetween. The resilient means are adapted to be compressed, upon receipt of an excessively large torque, i.e. in case of an overload, to allow a relative movement in the direction of rotation between the outer and the inner gear units. The relative movements of the gear units in the direction of rotation is then converted into a movement in the direction of thrust. Detecting switch is provided for opening an electric circuit for lifting, upon detecting the movement in the direction of thrust, thereby to stop the lifting operation.