A hydraulic intensifier comprising a reciprocating differential piston arrangement and a controller configured to control the supply of low pressure hydraulic fluid to the intensifier is provided. The controller comprises at least one solenoid operated pilot valve and electronic operator configured to operate the pilot valve.

A hydraulic piston pump motor in which water is used as a working fluid includes an axial directional passage opened on an end surface of one end of a shaft that couples to a cylinder block and drilled open along a shaft center of the shaft; a first radial directional passage drilled open along a radial direction of the shaft from the axial directional passage and configured to guide working fluid into a casing; a second radial directional passage drilled open from the axial directional passage along the radial direction of the shaft at a position closer to the one end of the shaft than the first radial directional passage; and an introduction passage communicating a passage, through which the higher pressure working fluid flows, among the supply passage and the discharge passage with the axial directional passage.

A hydraulic piston pump motor in which water is used as a working fluid includes an axial directional passage opened on an end surface of one end of a shaft that couples to a cylinder block and drilled open along a shaft center of the shaft; a first radial directional passage drilled open along a radial direction of the shaft from the axial directional passage and configured to guide working fluid into a casing; a second radial directional passage drilled open from the axial directional passage along the radial direction of the shaft at a position closer to the one end of the shaft than the first radial directional passage; and an introduction passage communicating a passage, through which the higher pressure working fluid flows, among the supply passage and the discharge passage with the axial directional passage.