Swash-plate type piston pump

A swash-plate type piston pump, comprising:

• a cylinder block configured to be rotated with rotation of a driving shaft;
• a plurality of pistons accommodated in a plurality of cylinders provided in the cylinder block;
• a swash plate configured to reciprocate the piston so that a volume chamber of the cylinder is expanded/contracted with the rotation of the cylinder block;
• a biasing mechanism configured to bias the swash plate in a direction where a tilting angle is made larger;
• a control pin configured to drive the swash plate in a direction where the tilting angle is made smaller in accordance with a rise in a load pressure of a pressure chamber;
• a discharge channel configured to discharge the load pressure of the pressure chamber;
• and
• a casing configured to accommodate the cylinder block, the piston, the swash plate, the biasing mechanism, and the control pin, wherein
• the control pin is slidably inserted into a pin cylinder provided in the casing;
• and
• one end of the discharge channel is opened at all times in a sliding gap between the control pin and the pin cylinder.