PURPOSE: To maintain the constant descending speed of a pallet, whether an automobile is loaded thereon or not, by providing a proportional valve, a reducing valve having an external drain type check and a compensation valve respectively between an actuator for elevating and lowering the pallet and a hydraulic source, and maintaining a constant differential pressure between the upstream and downstream sides of the proportional valve.

CONSTITUTION: For causing a pallet 11 to descend, a proportional valve 18 is kept at a position (b) and a selector valve 19 is selected at a position (b). As a result, oil is returned from a hydraulic cylinder 14 to a tank 22 via a reducing valve 20, the selector valve 19 and the proportional valve 18 in order, thereby causing the pallet 11 to descend. In this case, the reducing valve 20 acts to keep pressure constant at the upstream side of the valve 18, and differential pressure becomes constant between the upstream and downstream sides of the valve 18. Thus, flow control is undertaken in compensated pressure state. According to this construction, the descending speed of the pallet 11 can be kept constant, whether an automobile is loaded thereon or not.