Axial piston pump (pump Piston) is a piston or piston of the reciprocating movement direction of the cylinder with the central axis of the piston pump. Axial piston pump with the transmission shaft of the plunger in the plunger hole in the reciprocating movement generated by the volume changes to work. As the plunger and the plunger hole are circular parts, processing can achieve high accuracy with high volume efficiency, therefore.