To achieve the stable movement by guiding the sliding of a check with spool with the outer periphery at the rear side of the check spool and a small diameter rod at the top end part and connecting the hole into which the small diameter rod is inserted to a tank or an atmosphere release part.
A pilot check valve for working on and off an injection is composed of a sleeve 43, the check spool 45 slidably inserted in the sleeve 43 and opened/closed to a sheet 44 in the sleeve 43, a pilot piston 49 slidably inserted in a piston chamber 51 at the back side of the spool 45 and advancing/retreating with a pilot operating hydraulic oil and abutted to the back part of the spool 45, a spring 48 disposed between the back part of the spool 45 and the piston chamber 51 and the small diameter rod 52 extending the top end part of the spool 45 so as to slidably insert into the hole 55 of the guide 54 fitted to the top end part of the sleeve 43. Further, a servo unit comprises two pieces of servo valves and two working oil exhaust pipings are arranged at the front part of an injection cylinder and also, two servo valves are parallel disposed and the pipings are connected with the respective inlet sides and at the outlet sides, an intermediate block is arranged so as to constitute both pipings into a confluence.
NAKAGAWA KAZUMASA
KAI NOBUTAKA
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