Hydraulic cylinder

摘要

A hydraulic cylinder in which a recess (21) is formed in a piston rod (3) side end surface (20) of a piston (4) so that the recess (21) serves as an axial fitting portion, and an end of the piston rod (3) is fitted into the recess (21) of the piston (4) to ensure the coaxial relationship between the piston rod (3) and the piston (4). Axial threaded holes (24) are formed in an end surface (23) of the piston rod (3) and axial bolt through-holes (25) are formed in the piston (4). The end surface (20) of the piston (4) is disposed in face-to-face contact with the end surface (23) of the piston rod (3), and under the condition bolts (22) are inserted through the bolt through-holes (25) and screwed into the threaded holes (24) to fix the piston (4) to the piston rod (3). Accordingly, the strength of a piston connecting portion can be improved with a simple structure without use of any special high-strength material for the piston rod and without any special heat treatment.