PURPOSE: To obtain a small-sized actuator by shifting a piston for varying the volume to the fluid working equipment such as wheel brake in the axial direction by a working pressure determining means, cutting off the sealed chambers on both the sides of the piston by a valve means and cutting off the sealed chamber from a pressure source.
CONSTITUTION: As for an antiskid actuator 1, a piston 9 fitted in a cylinder 8 is energized towrds a neutral position by springs 18 and 19 which act to the position rods 16 and 17 installed at both the edges of the piston 9. The sealed chambers 14 and 15 which are dividedly formed on both the sides of the piston 9 are connected with a master cylinder pressure conduit 4 through shut-off valves 20 and 21, and one sealed chamber 14 is connected with a wheel cylinder 5, and the other sealed chamber 15 is connected with an accumulator 22. A ball screw 17a is formed at the top edge part of the piston rod 17, and the working pressure is controlled by shifting the piston 9 by revolving a ball nut 23 which is screwed with the ball screw 17a by the revolution of a pinion 26 by a torque motor 25.
FUJISHIRO TAKESHI
YOSHIOKA SHIGEKI