High pressure stall High pressure stall (4) 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 When the hydraulic system stalls under load or when the cylinders reach the end of the stroke, the main system pressure increases. But LS pressure (19) is regulated by LS relief valve on steering system and loader system.
The pressure difference between discharged pump and LS pressure equal to spring (18). It means no flow is necessary. Therefore, discharged pressure push flow compensator spool (13) left . Supply oil now flows past flow compensator spool (13) and through passage (23). The oil flows past flow compensator spool (13) and into passage (22). The oil then flows to control piston (10). Pump swash plate (2) will be minimum displacement if the operator does not turn the steering wheel and RCV, then the pump will return to low pressure standby. 6-18