Rotary swash plate hydraulic pump

A rotary swash plate hydraulic pump comprising:

• a casing;
• a cylinder block disposed in the casing so as to prevent relative rotation of the cylinder block and including a plurality of cylinder bores that are open on one end surface of the cylinder block;
• a rotary swash plate rotatably housed in the casing so as to face the one end surface of the cylinder block;
• a plurality of pistons each of which is inserted into a corresponding one of the plurality of cylinder bores and reciprocates within the corresponding one of the plurality of cylinder bores by rotation of the rotary swash plate;
• and
• a variable capacity mechanism that changes an effective stroke length of at least one piston included in the plurality of pistons, wherein:
• the variable capacity mechanism includes a plurality of spools arranged corresponding to the plurality of cylinder bores, respectively, and each of which reciprocates to open and close a path between a corresponding one of the plurality of cylinder bores and a tank, and changes the effective stroke length of the at least one piston by changing an opening/closing position of a corresponding one of the plurality of spools and placing at least a corresponding one of the plurality of cylinder bores and the tank in communication in a discharge process of the plurality of pistons.