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When lever 1 is turned counterclockwise about fixed axis D of the pump, fluid from tank 2 is drawn into cylinder 3 through suction valve 4. When lever 1 is turned in the opposite direction, fluid from the pump cylinder is delivered through opening ball-type discharge valve 8 into power cylinder 5, lifting plunger 6 of the jack together with the load. To lower the load, lever 1 is inclined clockwise somewhat farther than its extreme working position. At this, lug a of plunger 7 of the pump pushes back the ball of discharge valve 9, and pin d at the end of plunger 7 pushes back the ball of delivery valve 8. Both valves are opened and the fluid drains back to tank 2. The speed at which the load is lowered can be regulated by opening valves 8 and 9 more or less.