STRUCTURE AND FUNCTION HYDRAULIC PUMP OPERATION 1. Operation of pump 1) Cylinder block (7) rotates together with shaft (1), and shoe (5) slides on flat surface A . When this happens, rocker cam (4) moves along cy- lindrical surface B , so angle ( between center liner X of rocker cam (4) and the axial direction of cylinder block (7) changes. (Angle ( is called the swash plate angle.) 2) Center line X of rocker cam (4) maintains swash plate angle α in relation to the axial di- rection of cylinder block (7), and flat surface A moves as a cam in relation to shoe (5).
In this way, piston (6) slides on the inside of cylinder block (7), so a difference between volume E and F is created inside cylinder block (7). The suction and discharge is carried out by this dif- ference F - E . In other words, when cylinder block (7) rotates and the volume of chamber E becomes smaller, the oil is discharged during that stroke. On the other hand, the volume of chamber F becomes larger, so in that stroke, the oil is sucked in.
3) If center line X of rocker cam (4) is in line with the axial direction of cylinder block (7) (swash plate angle = 0), the difference between vol- umes E and F inside cylinder block (7) be- comes 0, so the pump does not carry out any suction or discharge of oil. (In actual fact, the swash plate angle never becomes 0.) 10-40