Moog RKP-II - Manual (Page 22)

Functional Description 3 Product Description
14 User Manual RKP-II (CA53461-001; Version 2, January 2010) © 2010 Moog GmbH
3.4 Functional Description
Functional Description The shaft (Pos. 11) transfers the drive torque to the star-shaped cylinder block
(Pos. 7), free of any axial forces, via a crossdisc coupling (Pos. 10). The
cylinder block is hydrostatically supported on the control journal (Pos. 6). The
radial pistons (Pos. 5) in the cylinder block run against the stroke ring (Pos. 3)
through hydrostatically balanced slipper pads (Pos. 4). The pistons and slipper
pads are joined by ball and socket joints and locking rings. The slipper pads
are guided in the stroke ring by two retaining rings (Pos. 2) and, when running,
are held against the stroke ring by centrifugal force and oil pressure.
As the cylinder block rotates, the pistons reciprocate due to the eccentric
positioning of the stroke ring, the piston stroke being twice the eccentricity. The
eccentric position of the stroke ring is controlled by two diametrically opposed
control pistons (Pos. 1, Pos. 8) and the pressure compensator (Pos. 9).
The oil flow to and from the pump passes through the pump ports and into and
out of the pistons through the porting in the control journal. The bearing
supporting the drive shaft is only subjected to external forces. The
compensator setting limits the system pressure and adjusts the pump flow
between zero and full flow to maintain the set pressure.
Fig. 4: Cross Section Radial Piston Pump RKP-II