Patent attributes
The overhead door lift assembly integrates a traditional torsion spring and an electrically powered operator into a small package mountable in the available head space of conventional tractor trailers, cargo vehicles or other structures. The lift assembly includes a torsion spring counterbalance, electrical operator, and back tension mechanism. The electrical operator uses an electromagnetic clutch and gearbox that couples directly to the cable drums of the counterbalance. The electromagnetic clutch allows the overhead door to be manually raised and lowered in the event of a power interruption or operator malfunction. The back tension mechanism prevents cables from inadvertently unspooling from cable drums as the operator starts to move the overhead door from its horizontal open position to its vertical closed position.
