Low pressure standby Low pressure standby (3) 1 2 4 6 14 15 LS pressure 12 13 X 21 10 24 22 L B 16 LS pressure oil System pressure oil Return oil L1 10 4 S 17 18 23 13 19 20 12 75796WE36 1 Drive shaft 2 Swash plate 4 Counter piston 6 Counter spring 10 Control piston 12 Pressure compensator spool 13 Flow compensator spool 14 Case drain 15 Passage 16 Passage 17 Spring 18 Spring 19 LS line from the metering pump 20 Cavity 21 Passage 22 Passage 23 Cavity 24 Cross-drilled hole Low pressure standby constitutes the following condition: a running engine and inactive steering and loader. There are no flow demands on the pump or pressure demands on the pump.
Therefore, there is no LS pressure in line (19). Before you start the engine, counter spring (6) holds swash plate (2) at the maximum angle. As the pump begins to turn, oil begins to flow and pressure increases in the system. Because of close centered steering control valve and close centered loader hydraulic system. As this pressure increase, the pressure pushes flow compensator spool (13) against spring (18). This causes flow compensator spool (13) to move left. This opens passage (23) in order to allow pressure oil to flow to control piston (10). The oil acts against control piston (10) in order to overcome the force of counter spring (6).
The oil causes control piston (10) to move to the left. When control piston (10) moves to the left, the piston moves swash plate (2) toward the minimum angle. Control piston (10) continues to move to the left until cross-drilled hole (24) allows the oil to drain to the case. 6-16