Patent ID: 8181756

Claim:
A shock absorber decreasing an impact force of a reciprocating rod provided in a reciprocating unit at a time of stopping the reciprocating rod, the shock absorber comprising: a hollow rod having an attaching hole formed therein and being attached coaxially with the reciprocating rod; an outer cylindrical body mounted outside the hollow rod and axially movable relatively to and coaxially with the hollow rod, a liquid accommodating space being formed between circumferential surfaces of the outer cylindrical body and the hollow rod, and separated from the attaching hole; an annular piston provided outside the hollow rod so as to be slidable axially along the hollow rod, partitioning the liquid accommodating space into a first liquid chamber and a second liquid chamber each separated from the attaching hole, and applying a resistance force to a flow of the liquid from the first liquid chamber to the second liquid chamber at a time of an impact-force absorption movement of the hollow rod to the outer cylindrical body; a restoring means provided in the first liquid chamber and returning the hollow rod to an original position located before an impact-force absorption; an outside gap formed between an outer circumferential face of the annular piston and an inner circumferential face of the outer cylindrical body, and applying a resistance force to the flow of the liquid from the first liquid chamber to the second liquid chamber; and an inside gap formed between an inner circumferential face of the annular piston and an outer circumferential face of the hollow rod, and guiding the liquid from the second liquid chamber to the first liquid chamber together with the outside gap.