Page 132 - Fluid Power Engineering

106 Cha pte r F o u r

FIGURE 4.17 The inclined pistons swash plate pump.

4.6.4 Axial Piston Pumps with Rotating Swash
Plate-Wobble Plate
In axial piston pumps with rotating swash plates (see Fig. 4.18), the
swash plate is rotated by the driving shaft. The cylinder block is fixed.
The pistons are displaced inwards by the rotating swash plate, while
the piston displacement in the opposite direction is insured by a
spring. During the pump operation, the pumping chamber is con-
nected with the inlet and exit lines through the check valves. The inlet
line check valves should be of low cracking pressure to avoid pump
cavitation. The pump displacement is calculated by Eq. (4.25).

4.6.5 Radial Piston Pumps with Eccentric Cam Ring
Radial piston pumps are usually used in applications requiring high
pressures, above 400 bar. In presses, for example, operating pressures
are required to be up to 700 bar. The radial piston pumps can operate