TM 5-3805-258-24-1S T E E R I N G S Y S T EMS U P P L E M E N T A L S T E E R I N G S Y S T EMS Y S T E M S O P E R A T I O Npassage (18) to the right end of reversing spool (14).The force of this oil moves the reversing spool to theleft. Oil from the supplemental pump can then flowfrom passage (17) into passage (3). Passage (3) takesthe oil to check valve (11) and diverter spool (1).If the engine rpm is low, the diverter spool will beto the left. Oil flow past the diverter spool is stopped.The pressure of the oil in passage (3) increases untilcheck valve (11) opens. This lets the oil from thesupplemental pump flow past check valve (11) tocheck valve (8). The oil then flows together with theoil from the primary system and goes through outlet(5). This combined flow of oil then goes to the steer-ing control valve.DIVERTER VALVE SCHEMATIC(Engine at LOW rpm end Machine in FORWARD Motion)1. Diverterspool. 2. Return passage to hydraulic tank. 3.Paasage. 4. Spring. 5. Outlet to steering control valve.6.Paaaage. 7. Orifice. 8. Checkvalve.9. Passage. 10. Inletfrom primary steering pump section. 11. Check valve.12.Supply paasage (for supplemental steering pump). 13.Spring. 14. Reversing spool. 15. Passaga to left end ofspool. 16. Pasaage. 17. Paaaage. 18. Passage to right endof spool.If the engine rpm is high, diverter spool (1) will beto the right. The oil from the supplemental pumpflows into passage (3). The oil flows around spool (1),into passage (2), and back to the hydraulic tank.Only the primary pump flow is sent to the steeringcontrol valve through outlet (5). Check valve (11)will not let the primary oil flow into passage (3).If there is a failure of the primary steering pumpsection, or if the engine stops there will be a loss ofprimary flow. Diverter spool (1) will move to the left.As long as the machine moves, the flow from thesupplemental pump will provide the oil for the steer-ing operation. The oil will flow through passage (3),past check valve (11), and through outlet (5). Checkvalve (8) will prevent the loss of flow through inlet(10), and the stopped primary pump.When the machine moves in a reverse direction,the supplemental pump turns in the opposite direc-tion. The pressure oil from the pump is sent throughpassages (16) and (15) to the left end of reversingspool (14). This causes the spool to move to the right.The pressure oil can then flow through passage (16)into passage (3). The rest of the oil flow is the same aswhen the machine moves forward.DIVERTER VALVE SCHEMATIC(Engine at HIGH rpmand Machine in Forward Motion)1. Diverterspool. 2. Return passage to hydraulic tank. 3.Passage. 5. Outlet to atearing control valve.6. Pas-sage.7. Orifice. 8. Check valva.9. Passage. 10. Inlet fromprimary steering pump section. 11. Checkvalve.12. Sup-ply passage (for supplemental steering pump). 13.Spring. 14. Reversing spool. 15. Passage to left end ofspool. 16. Passage. 17. Passage. 18. Passage to right endof spool.3-69
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