Hitachi Construction Machinery Co., Ltd.

Hitachi, Ltd.

Hitachi Construction Machinery

Eiji Kometani

Ken Ichiryu

Yasuharu Gotoh

Morio Tamura

Kazuyoshi Hatano

Nobuyoshi Hidao

Ichiro Nakamura

Eiichi Hazaki

Masaya Imai

Yoshimichi Akasaka

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 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

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.

Thrust hydrostatic bearing device for use in axial piston machine

A hydraulic pump or motor having: oil grooves in the internal partial-spherical surface of a piston for introducing pressure oil between said internal partial-spherical surface and a ball; oil grooves in the peripheral surface of the large diameter portion of said piston for introducing pressure oil between the outer peripheral surface of the large diameter portion of said piston and a cylinder; small diameter passages provided through said piston and extending from the upper end of said piston to said oil grooves, while communicating with an oil chamber for said piston; and necked or throttle portions provided in said small diameter passages, respectively, to thereby give rise to pressure drops for oil which is passing through said small diameter passages.

Hydraulic pump or motor

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Eiji Kometani