Abstract: A portable lifting jack has a drivable mechanism operating a jack shaft formed of telescoping lifting screws. A microprocessor controls power to selectively turn electric motor to drive the operating mechanism. An in-line current draw sensor senses electric load of the motor and communicates this to the microprocessor. One detected electrical load is an electric load spike indicative that the jack shaft has contacted a mechanical load. A potentiometer connected to the operating mechanism senses extended position of the telescoping lifting screws and communicates this position to the microprocessor, which is programmed to derive when snug contact is achieved with an encountered mechanical load and to pause operation of the electric motor. In a synchronized array of jacks, all are paused to await further operator input, which may be coordinated through a remote control.

Abstract: A portable lifting jack has a drivable mechanism operating a jack shaft formed of telescoping lifting screws. A microprocessor controls power to selectively turn electric motor to drive the operating mechanism. An in-line current draw sensor senses electric load of the motor and communicates this to the microprocessor. One detected electrical load is an electric load spike indicative that the jack shaft has contacted a mechanical load. A potentiometer connected to the operating mechanism senses extended position of the telescoping lifting screws and communicates this position to the microprocessor, which is programmed to derive when snug contact is achieved with an encountered mechanical load and to pause operation of the electric motor. In a synchronized array of jacks, all are paused to await further operator input, which may be coordinated through a remote control.