Bent axis type axial piston pump/motor

A bent axis type axial piston pump/motor comprising:

• a cylinder block, which is arranged inside a casing, has a shaft attachment hole on a shaft center of one end face, and includes a plurality of cylinder bores on a circumference having the shaft center as a center;
• a plurality of piston rods, each of which are arranged in the cylinder bores of the cylinder block with a supporting end projecting out from the cylinder block;
• a center shaft, which has a base portion attached to the shaft attachment hole of the cylinder block and has a supporting end projecting out from the shaft attachment hole;
• a drive shaft rotatably supported by the casing with one end arranged inside the casing;
• a retainer plate for supporting the supporting end of the center shaft in a tiltable manner at a position to be on a shaft center at one end face of the drive shaft arranged inside the casing, and supporting the supporting end of the piston rod in a tiltable manner on a circumference having the shaft center as a center at one end face of the drive shaft;
• a valve plate, which is interposed between another end face of the cylinder block and the casing, rotatably supports the cylinder block at inside the casing, and carries out a switching control of pressure with respect to the plurality of cylinder bores according to a rotation position of the cylinder block;
• and
• a push spring, which is arranged in the shaft attachment hole of the cylinder block to act to push the cylinder block against the valve plate,
• the piston rod stroke moving in the cylinder bore according to tilt angles of the drive shaft and the cylinder block when the drive shaft and the cylinder block are rotated around the shaft centers respectively, wherein
• the center shaft includes,
• an outer race, which is attached to the shaft attachment hole of the cylinder block, includes a shaft portion accommodation hole at one end, and includes a spring accommodation hole at the other end, and
• an inner shaft, which includes a supporting portion having an outer shape dimension larger than the base portion at a distal end of the base portion having a shaft shape, and is attached to the shaft portion accommodation hole of the outer race through the base portion, and
• one end of the outer race is attached to the shaft attachment hole of the cylinder block with the push spring accommodated in the spring accommodation hole, and supported in a tiltable manner at an end face of the drive shaft by way of the supporting portion of the inner shaft.