Abstract: In a hydraulic rotary machine having rotational shaft provided within a casing a rotational shaft, a cylinder block rotationally interlocked with the rotational shaft and formed with a plural number of cylinder bores, and pistons slidably received in the cylinder bores and adapted to slide back and forth within the cylinder bores while the rotational shaft and the cylinder block are put in rotation in synchronism with each other, a multitude of minute pits are formed at least either on sliding surfaces on the side of the cylinder bores, each one of the minute pits are in an elliptical shape defining a moderately sloped surface in one side and an acutely sloped surface in the other side, and the moderately sloped surfaces of the minute pits are oriented to face a direction in which said pistons are put in sliding movement in said cylinder bores under a greater load than in the other direction.

Abstract: In a hydraulic rotary machine having rotational shaft provided within a casing a rotational shaft, a cylinder block rotationally interlocked with the rotational shaft and formed with a plural number of cylinder bores, and pistons slidably received in the cylinder bores and adapted to slide back and forth within the cylinder bores while the rotational shaft and the cylinder block are put in rotation in synchronism with each other, a multitude of minute pits are formed at least either on sliding surfaces on the side of the cylinder bores, each one of the minute pits are in an elliptical shape defining a moderately sloped surface in one side and an acutely sloped surface in the other side, and the moderately sloped surfaces of the minute pits are oriented to face a direction in which said pistons are put in sliding movement in said cylinder bores under a greater load than in the other direction.

Abstract: Cooling water is sprayed under a predetermined pressure range and at a predetermined discharge rate over the both surfaces of a sheet to be treated which is reciprocated lengthwise at such a velocity that the product of the reciprocating velocity and thickness of the sheet may be maintained within a predetermined range. The spraying direction of each spray nozzle is individually controlled so that any water remaining over the surface of the sheet may be expelled out. The method and apparatus is especially adapted for use in the normalizing process and in the process for cooling hot-rolled sheet steel.