HYDRAULIC JACK

PURPOSE:To perform constantly light operation of an operation handle by providing a valve means capable of being switched according to a heavy load and a light load state and switching a feed route for pressure oil to a ram cylinder, in a manual operation type hydraulic jack used for a hand pallet truck. CONSTITUTION:The pressure of oil in an oil tank 2 is increased by reciprocation of a plunger 8 through rotational operation of an operation handle 15 and pressure oil the pressure of which is increased is fed to a ram cylinder 3 to lift a ram 4. A pump port on the lower pressure side and a pump port on the high pressure side communicated with the large and small inside diameter parts 7a and 7b, respectively, of a pump cylinder 7 are respectively formed in the intermediate part of an oil passage running between the plunger 8 and the ram cylinder 3 and communicated with a through-hole 23. A suction valve, a suction and delivery valve, and delivery valve are incorporated on the same axis in the through-hole 23 and the valves are switched and controlled to a ram rise position during a light load, a ram rise position during a heavy load, a ram neutral position, and a ram machining position by means of a valve switching member 51.