Multi-stage shock absorber

PROBLEM TO BE SOLVED: To solve without increase of friction resistance of a piston, a problem that the intermediate member of a multistage shock absorber deviates off a required level and collided with both side members. SOLUTION: When the rod 4 of a small diametral unit 1 is penetrated into a cylindrical body 3 by a part of X1, hydraulic fluid is led to flow into the insides of the contraction chamber 17 of a large diametral unit 2 and a peripheral oil chamber 16b through holes 3a, 15a by the volumetric part V1 (=Ar×X1) that the rod 4 is penetrated into the cylindrical body 3. Hydraulic fluid flow makes a piston 15 and the cylindrical body 3 penetrate lower into a cylindrical body 11 by X2=V1/(APU-APL+Ab). At this time, hydraulic fluid is led to flow from a center oil chamber 16a into the inside of an auxiliary chamber 14 through a vibration damping valve 19, and gas in the auxiliary chamber 14 is compressed. X2=X1×Ar/(APU-APL+Ab) can be obtained from the above-mentioned enumeration expression of X2, V1, the relation between X2 and X1 is determined by Ar/(APU-APL+Ab), and the cylindrical body 3 being an intermediate member can be prevented from being collided with both side members. Load is supported by differential pressure between lower side hydraulic pressure PL and upper side hydraulic pressure PU, and lower side hydraulic pressure PL and upper side hydraulic pressure PU are partitioned by a cylindrical contraction member 21, thus the periphery of the piston 15 does not need to seal.