Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Described is a bent axis type variable displacement hydraulic machine which is provided with a hydrostatic radial bearing 23 and/or a hydrostatic thrust bearing 28 to support hydraulic reaction forces exerted on a cylinder block 8. The hydraulic machine is arranged to draw out a high oil pressure corresponding to the tilt angle of the cylinder block 8 through a variable throttle means 34, 37, 51 or 54 or through a control valve 77 or 78, and to supply the pressure to the hydrostatic radial or thrust bearing 23 or 28 thereby imparting to a hydrostatic supporting capacity commensurate with the tilt angle of the cylinder block 8 to support a rotational shaft stably while holding oil leaks to a minimum.

Abstract: A bent axis type variable displacement hydraulic machine employing hydrostatic radial bearings for supporting hydraulic reaction forces exerted on the cylinder block. In a hydraulic machine of this sort, the number of pistons which are located in the high pressure are varies with the rotation of the cylinder block, and the resultant force of hydraulic reaction forces has an acting point at a position off the axis of the rotational shaft. Therefore, the hydrostatic radial bearings are located in such positions as to balance the moment loads which occur about the rotational shaft in relation with the acting point of the resultant force of radial hydraulic reaction forces on the drive disc of the rotational shaft. As a result, it becomes possible to lead to suppression of oil leaks from the sliding surfaces to a minimal rate and to prevent abnormal abrasive wear of each of the sliding surfaces.

Abstract: 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.

Abstract: 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.