Hitachi Construction Machinery Co., Ltd.

Hitachi, Ltd.

Hitachi Construction Machinery

Yasuharu Gotoh

Ichiro Nakamura

Ken Ichiryu

Yoshimichi Akasaka

Eiji Kometani

Morio Tamura

Kazuyoshi Hatano

Nobuyoshi Hidao

Eiki Izumi

Shigetaka Nakamura

A sliding member is sulphonitride by heating at 480.degree.-600.degree. C. in the presence of both 10-500 ppm of a hydrogen sulfide gas and a 20-70 vol % ammonia gas, or by a method which comprises performing a primary heat treatment on the sliding member at 450.degree.-540.degree. C. in the presence of 50-200 ppm of a hydrogen sulfide gas and a 10-70 vol % ammonia gas, then ceasing the supply of the ammonia gas, slowly reducing the temperature to a level of 200.degree.-350.degree. C., and performing a secondary heat treatment at that temperature level. By the either method, the sliding member having a FeS.sub.2 on its topmost surface can be obtained.

Method of gas sulphonitriding

A bent-axis type variable displacement hydraulic machine provided with one of a hydrostatic radial bearing and a hydrostatic thrust bearing to support hydraulic reaction forces exerted on a cylinder block. The hydraulic machine is adapted to draw out a high oil pressure corresponding to a tilt angle of the cylinder block through a variable throttle means or through a control valve, and to supply the pressure of the hydrostatic radial or thrust bearing to thereby impart a hydrostatic supporting capacity commensurate with a tilt angle of the cylinder block and stably support a rotational shaft while minimizing oil leaks.

Bent axis type variable displacement hydraulic machine

A sliding member having a layer of FeS.sub.2 on its surface is formed by sulphonitriding the member by heatint it at 480.degree. C.-600.degree. C. in the presence of both 10-500 ppm of a hydrogen sulfide gas and 20-70 vol % ammonia gas. An alternate heating method involves performing a primary heat treatment on the sliding member at 450.degree.-540.degree. C. in the presence of 50-200 ppm of a hydrogen sulfite gas and a 10-70 vol % ammonia gas, then ceasing the supply of the ammonia gas, slowly reducing the temperature to between 200.degree.-350.degree. C., and performing a secondary heat treatment at that temperature level.

Sliding member, and method and apparatus for producing the same by gas

Described herein is a variable displacement bent axis type hydraulic machine having a center shaft within a casing in a tilted state along with a valve plate and a cylinder block, and provided with a tilt angle sensor mechanism for detecting the tilt angle of the valve plate. For the purpose of improving the resolution in angle detection, the tilt angle sensor mechanism is constituted by a support shaft rotatably supported on a side wall of the casing at a position deviated toward the valve plate from the pivoting point of the center shaft, a rocking lever having one end thereof securely fixed to the support shaft and the other end pivotally supported at one side of the valve plate, and an angle sensor adapted to detect the rotational angle of the support shaft resulting from rocking movement of the rocking lever. This arrangement permits a wider rotational angle for the support shaft to guarantee higher resolution in the tilt angle detection.

Variable displacement bent axis type hydraulic machine

A thrust hydrostatic bearing device for use in an axial piston machine includes a bearing sleeve fitted into a housing cover for rotatably supporting a drive shaft through a bearing and having a plurality of hydrostatic pads. The hydrostatic pads are disposed at locations which are symmetrical with respect to an axis lying in a cross-section taken perpendicular to the drive shaft, and these pads increase the performance and durability of the thrust hydrostatic bearing device for use in an axial piston machine.

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Tsuchiura, Japan

Yasuharu Gotoh