The main drive shaft driven in part by the cylinder rotation, uniformly distributed over seven cylinder plunger shaft around the center line of rotation, by the spring center column slide shoe assembly against the variable head (or swash plate) on . Thus, with the rotation of the cylinder and the piston reciprocates complete oil suction and pressure operation. Quantitative swash plate mechanism is always fixed on quantitative cap, we can not change the stroke of the plunger, so that the flow rate is fixed. The pump is only to replace the oil pan can also be used as a motor oil.