Description

Type 4012 is an effective hoist controller for applications where speeds can very with the load and frequent lowering is not required.  Timing devices or frequency responsive relays for accelerating contactors provide smooth acceleration control.

The first hoist position of the master switch provides low torque for taking up slack cable and hoisting light loads.  Subsequent master switch points allow additional contactors to close until the desired hoisting speed is attained.  Movement of the master switch in the lowering direction produces similar results.  The load is driven downward against the retarding action of the mechanical load brake and timed or frequency responsive accelerating relays provide smooth acceleration.

Type 4012 reversing control panels are suitable for use with a ac wound rotor motors on crane hoist drives.

Type 4012 controllers are for use on hoists that are equipped with a mechanical load brake or a means of providing control of overhauling loads.  These controllers provide good speed control hoisting and lowering, within the capability of the mechanical load brake.