MULTI-STAGE TYPE ACTUATOR

PURPOSE:To enable both generation of long stroke within a small space and easy manufacture of each of piston/cylinders constituted in multi stages by forming fluid flow bypasses communicating the internal and external parts to each other inside the small-diameter parts of said cylinders. CONSTITUTION:To elongate each of cylinders, fluid is first fed into them from a piping 51 which is connected to a cylinder tube 15. Fluid then have a primary piston/cylinder 30 elongated to the right and some of the fluid flows into a chamber III through a hole 10. The fluid then has a secondary piston/cylinder 35 elongated to the right and some of the fluid flows into a chamber V through a hole 11, thereby elongating a piston 37. At this time, fluid staggered in a chamber VI is forced to run into a chamber IV through a bypass passage 41. Fluid staggered in the chamber IV then flows into a chamber II through a bypass passage 42 when the piston 37 is distorted. Finally, the fluid flows out from the chamber II via a piping 52.