Hitachi Construction Machinery Co., Ltd.

Yoshitomo Yabuuchi

Takeshi Kobayashi

Takashi Niidome

Naoyuki Okuno

Tsuyoshi Yamada

A nitriding layer () is formed on the front surface side of a base material of a cylinder block () including an opening side end surface (B) and each cylinder hole (). Then, a piston sliding surface (A) of each cylinder hole () is formed as a compound layer-removed hole () by removing a compound layer () that is located on the front surface side of the nitriding layer () by using polishing means such as, for example, honing and so forth. Further, a compound layer-removed surface () is formed on a part (A) where a compound layer-removed hole () and a cylinder inlet side tapered surface (B) of each cylinder hole () intersect by using the polishing means such as, for example, the honing and so forth. This compound layer-removed surface () is formed as a tapered-state inclined surface of an angle &#x3b1;.

Axial piston-type hydraulic rotary machine

A motion converting section () and a translation bar () of a feedback mechanism () are provided between a lateral side of a swash plate () and a control sleeve () of a regulator (). When the swash plate () is in a neutral position, the motion converting section () is located in an initial position (F&#x2014;F) at one end of axial direction along an axis line (O&#x2014;O) passing through a tilting center (C) of tilting motions, and, when the swash plate () is driven to tilt in a forward or reverse direction, displaced to the other end of axial direction along the axis line (O&#x2014;O) to convert a tilting motion of the swash plate () into an axial displacement. Through the translation bar (), the axial displacement is transmitted to the control sleeve () of the regulator () as an axial displacement.

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Kasumigaura, Japan

Yoshitomo Yabuuchi