To reduce machining manhour of communicating passages by providing a check valve at each communicating passage for communicating each cylinder hole to an operating oil storage chamber, and forming an orifice at a valve element of the check valve.
Each cylinder hole 2d is communicated with an operating oil storage chamber through each separate communicating passage 10. Each mounting hole 2h extended from the peripheral surface of a disc part 2b to the inner circumferential surface of the operating oil storage chamber is provided with a check valve 9. The check valve 9 is so constituted that when the operating oil in the cylinder hole 2d is going to flow toward the operating oil storage chamber, a valve element 92 is seated on a valve seat to impede it, and when operating oil in the operating oil storage chamber is going to flow toward the cylinder hole 2d, the valve element 92 is lifted from the valve seat 92 against the energizing force of a spring to allow it. A through hole 92a is piercingly formed in the valve body 92 of the check valve 9, and an orifice 92b is formed at the operating oil storage chamber side end part of the through hole 92a.
ISHIKAWA ISAO
NAKAJIMA SHINICHIRO
