Patent ID: 8302746

Claim:
A hydraulic shock absorber which comprises: a primary piston which is slidably fitted into a cylinder and partitions the cylinder into first and second fluid chambers; and a piston rod which is connected to the primary piston and slidably penetrates through an end wall of the cylinder, the piston rod comprising an enlarged-diameter portion which extends through the end wall of the cylinder, and a reduced-diameter portion integrally attached to the enlarged-diameter portion; wherein: a step portion of the piston rod is defined between the enlarged-diameter portion and the reduced-diameter portion; the piston rod penetrates through the primary piston, and includes on the outer circumferential surface of the piston rod at least one groove which selectively communicates between the first and second fluid chambers, the groove extending in an axial direction along the piston rod from an area of the enlarged-diameter portion proximate the step portion to an area of the reduced-diameter portion; and the first and second fluid chambers are communicated with each other through the at least one groove.