HOIST CONTROL WITH LIMIT SWITCHES

摘要

A hoist control system having a limit switch assembly is utilized in a pendant controlled pneumatic hoist to limit hoist travel to a predetermined range within preset upper and lower limits. The hoist travel limits and the range are controlled by a pair of limit switches which are actuated by a pair of actuating members which move in response to rotation of the hoist motor. The initial positions of these movable members are independently preset by initially setting them on a threaded shaft which is mounted proximately to the limit switches. The shaft rotates in response to hoist motor rotation causing the constrained movable members to move linearly along the threaded rotating shaft until they actuate one of the limit switches. The actuated limit switch controls a valve assembly to prevent supply air from driving the hoist motor to thereby stop further hoist movement.