| 摘要 |
The present invention comprises a support frame secured within the cargo box of a pick up truck. The frame supports a drive train comprising a differential driven by an motor. One differential shaft drives a first cable winch while the other shaft incorporates a clutch to drive a second and third winch either independantly from each other or in unison. A system of pulleys ensures that cable wind on the first and second winches is toward the front of the cargo box while on the third winch it is toward the rear. The cable ends are secured to a cargo platform. When the electric motor is engaged the first and second winches are rotated, in a counterclockwise direction which winds the cable into the winch body. The retracting cable first raises and then draws the platform onto the frame. During this process the third winch freewheels and releases cable as necessary. Unloading the platform requires that the clutch mechanism is engaged to couple the second and third winches together. The motor is reversed and the first, second, and third winches rotate in a clockwise direction. The third winch retracts cable while the first and second winches release cable. The retracting cable, draws the platform off the support frame and toward the rear of the cargo box. As the platform draws far enough rearward to tilt off the support frame, the clutch is disengaged and the third winch freewheels, leaving the platform to continue to lower under its own weight.
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