HY28-2668-01/GC/NA,EU
GOLD CUP
®
Series - Application Manual
Piston Pumps & Motors
1.5
Parker Hannifin Corporation
Hydraulic Pump Division
Marysville, Ohio USA
Section 1
Figure 1.9 shows the ring checks which are used for replenishing check valves. The ring
checks are located in the main ports (Figure 1.4). They consist of cylindrical shaped spring
steel strips wrapped inside each system port and held in place by a retainer screw and nut.
Large port areas at the ring check allow higher flow rates with small motions of the ring,
thereby reducing bending and fatigue. Upon closing, a squeeze film between the ring and
bore dampens the motion and prevents pounding. Both of these features are responsible for
the high reliability and fast response of this check valve design.
The valve block assembly bolts to the top surface of the pump port block at the rear. This as-
sembly holds the pressure compensator overrides valves, servo relief valve and replenishing
relief valves and can be removed and replaced as an assembly. Its functions and the circuitry
are described in the Circuitry Section 2.
GOLD CUP
®
hydrostatic transmission package motors are equipped with hot oil shuttle valves
and low pressure replenishing relief valves as standard. They are available in both variable
and fixed displacement versions.
All package motors use a rotating group of the same principle and design as the package
pump. There are slight internal porting differences to enhance the motoring capabilities.
Fixed displacement motors (Figure 1.10) have a fixed-angle cam instead of a rocker and
cradle assembly. There are no stroking mechanisms or controls.
PACKAGE MOTOR
CONFIGURATION
Figure 1.10
Fixed displacement motor
Figure 1.9
Ring check assembly
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