Weight operated limit switches are used on control/power circuit of reversing drives so as to limit their rotation/movement with in a predetermined position. complying to IEC/EN 60947-5-1, IEC/EN 60529, IEC 60068-2-78, IEC 60068-2-30.
When the snatch block of the crane reaches its top position the snatch boxes pushes a plate which is hanging from one end of the lever of the limit switches. due to the weight placed on the other end of the lever, this lever is pushed up. when the lever is pushed up the shaft to which this lever is connected rotates there by rotating the cams which eventually open the contacts.