Patent ID: 7467723

Claim:
A hoist system including an elevated support for an upper hoist assembly including an electric motor driving a self locking worm gear and worm wheel in turn driving a chain drive engaging a hoist chain to positively drive said chain up or down, said hoist chain having a load support structure to an upper portion of said load support structure, said load support structure adapted to hold a load at a lower end of said load support structure to be raised or lowered by said driving of said hoist chain; a first load sensor connected between said upper and lower portions of said load support structure so as to sense the weight of said load, and generate corresponding signals; a control grip suspended from said upper portion of said load support structure at a location above said first load sensor, with a second load sensor connected to said control grip to only sense up or down forces manually exerted on said control grip by an operator and generate corresponding signals, said forces manually exerted on said control grip not affecting the load sensed by said first load sensor and said load not sensed by said second load sensor; said signals of both said first and second sensors transmitted to a hoist control to selectively allow a float mode in which said electric motor is only activated in response to forces directly exerted by a supported load to raise or lower a supported load; or, alternatively, a manual mode in which said electric motor is activated only in response to forces manually exerted on said control grip to raise or lower a supported load.