PURPOSE: To improve riding comfortableness while reducing fluttering motion by arranging the second movable member, which moves in the direction of narrowing a cross sectional area of a flow passage in the case of resonance, on the flow passage in which the cross sectional area is changed by means of the first movable member so that resonant frequency of a sub spool can be set to accord with the resonant frequency of a suspension.
CONSTITUTION: In a nut 18 attached on the tip of a piston rod 9, a spool body 24, etc., is mounted inside of its cylindrical housing part 18a. Here, a main spool 40 as the first movable member for defining the inside of the spool body 24 into an expanding side pressure receiving chamber D1 and a compression side pressure receiving chamber D2 is arranged slidably inside spool body 24, while on the one hand, a sub spool 50 as the second movable member is arranged slidably in a flow passage 9a formed on a piston rod 9. On the basis of elastic force of springs 51 and 52 to support the sub spool 50 from the upper and lower sides and mass of the sub spool 50, this sub spool 50 sets its resonant frequency to accord with resonant frequency of a suspension.
TSUCHIYA YUKIHIRO
KANARI ITSUYO
ATSUGI UNISIA CORP