Plunger pump

A plunger pump comprising:

• a cylinder having inside a cylinder chamber;
• a plunger disposed in the cylinder so as to be relatively movable forward and backward to the cylinder chamber so that an outer circumferential face of the plunger is in slide contact with an inner circumferential face of the cylinder, and having a cut face on an outer periphery of an distal end;
• and
• a suction port and a discharge port provided to the cylinder to communicate with the cylinder chamber,
• the plunger pump transferring fluid by reciprocating the plunger in an axial direction while rotating the plunger relative to the cylinder chamber to let the suction port and the discharge port alternately communicate with the cylinder chamber,
• wherein the cylinder includes a cylinder main body and a spacer section being disposed in an inner portion of a proximal end side of the cylinder main body, and sliding against a portion of the plunger closer to the proximal end side than a portion of the plunger advancing and retracting into the cylinder chamber, and
• the plunger pump further comprises a seal section provided on the proximal end side of the cylinder for sealing the cylinder main body, the plunger and the spacer section.