Hitachi Construction Machinery Co., Ltd.

Akinori Ro

Mitsuhiro Yoshimoto

Tomohiko Yasuoka

A hydraulic cylinder in which a recess ( ) is formed in a piston rod ( ) side end surface ( ) of a piston ( ) so that the recess ( ) serves as an axial fitting portion, and an end of the piston rod ( ) is fitted into the recess ( ) of the piston ( ) to ensure the coaxial relationship between the piston rod ( ) and the piston ( ). Axial threaded holes ( ) are formed in an end surface ( ) of the piston rod ( ) and axial bolt through-holes ( ) are formed in the piston ( ). The end surface ( ) of the piston ( ) is disposed in face-to-face contact with the end surface ( ) of the piston rod ( ), and under the condition bolts ( ) are inserted through the bolt through-holes ( ) and screwed into the threaded holes ( ) to fix the piston ( ) to the piston rod ( ). 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.

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Ibaraki-ken, Japan

Akinori Ro