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| Illustration 1 | g03687461 |
Diverter valve cutaway (engine at low idle and machine stopped) (1) Diverter spool (2) Return passage to hydraulic tank (3) Passage (4) Spring (5) Outlet to steering control valve (6) Passage (7) Orifice (8) Check valve (9) Passage (10) Inlet from steering pump (11) Check valve (12) Supply passage for secondary steering pump (13) Spring (14) Reversing spool (15) Passage to left end of reversing spool (16) Passage (17) Passage (18) Passage to right end of reversing spool | |
The main components of the secondary steering diverter valve are: diverter spool (1), check valves (8), and reversing spool (14) .
When the engine is running, the oil from the steering pump flows through inlet (10) and orifice (7) to check valve (8). The force of the oil opens the check valve. The oil flows past the check valve and through outlet (5) to the steering control valve. Check valve (11) will not allow oil to flow to passage (3) .
The pressure of oil before orifice (7) is more than the pressure of oil after the orifice. These pressures are also felt through passages (9) and (6) respectively.
The oil before orifice (7) flows through passage (9) to the left side of diverter spool (1). The pressure of the oil after orifice (7) is the same as the pressure of the oil to the right end of diverter spool (1).
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| Illustration 2 | g03687466 |
Schematic for the diverter valve (1) Diverter spool (2) Return passage to hydraulic tank (3) Passage (4) Spring (5) Outlet to steering control valve (6) Passage (7) Orifice (8) Check valve (9) Passage (10) Inlet from steering pump (11) Check valve (12) Supply passage for secondary steering pump (13) Spring (14) Reversing spool (15) Passage to left end of reversing spool (16) Passage (17) Passage (18) Passage to right end of reversing spool | |
As the engine rpm increases, the oil flow from the steering pump also increases. Due to the increased oil flow past orifice (7), there is an increase in the difference of the oil pressure before and after the orifice.
When the force of the oil on left end of diverter spool (1) is more than combined force of oil and spring (4) on the right end, diverter spool (1) will move to the right.
No oil is sent from the secondary steering pump until the machine moves. When the machines moves, the pump is turned by the output transfer gears in the transmission. Oil from the hydraulic tank is supplied to the secondary pump through supply passage (12). Oil flows from the hydraulic tank through supply passage (12), to reversing spool (14).
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| Illustration 3 | g03687473 |
Diverter valve cutaway (engine at low idle and machine in forward motion) (1) Diverter spool (2) Return passage to hydraulic tank (3) Passage (4) Spring (5) Outlet to steering control valve (6) Passage (7) Orifice (8) Check valve (9) Passage (10) Inlet from steering pump (11) Check valve (12) Supply passage for secondary steering pump (13) Spring (14) Reversing spool (15) Passage to left end of reversing spool (16) Passage (17) Passage (18) Passage to right end of reversing spool | |
When the machine moves in a forward direction, the secondary steering pump sends pressure oil into passage (17). The pressure of this oil is felt through passage (18) to the right end of reversing spool (14) .
The force of this oil moves the reversing spool to the left. The oil flows through passage (16) to the secondary steering pump. Oil from the secondary pump can then flow from passage (17) into passage (3). Passage (3) routes the oil to check valve (11) and diverter spool (1) .
If the engine rpm is low, diverter spool (1) will be to the left. Oil flow past the diverter spool is stopped. The pressure of the oil in passage (3) increases until check valve (11) opens.
When check valve (11) opens, oil from secondary steering pump flows past check valve (11) and combines with the oil from the main steering system and flows through outlet (5). This combined oil then flows to the steering control valve.
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| Illustration 4 | g03687477 |
Diverter valve cutaway (engine at high idle and machine in forward motion) (1) Diverter spool (2) Return passage to hydraulic tank (3) Passage (4) Spring (5) Outlet to steering control valve (6) Passage (7) Orifice (8) Check valve (9) Passage (10) Inlet from steering pump (11) Check valve (12) Supply passage for secondary steering pump (13) Spring (14) Reversing spool (15) Passage to left end of reversing spool (16) Passage (17) Passage (18) Passage to right end of reversing spool | |
If the engine rpm is high, oil flow from the steering pump increases. Because of the increased oil flow past orifice (7), there is an increase in the difference of the oil pressure before and after the orifice.
When the force of the oil on left end of diverter spool (1) is more than the combined force of the oil and spring on the right end, diverter spool (1) will shift to the right.
The oil from the secondary steering pump flows into passage (3). The oil flows around spool (1), into passage (2), and back to the hydraulic tank. Only the main steering pump flow is sent to the steering control valve through outlet (5). Check valve (11) will not let the steering pump oil flow into passage (3) .
If there is a failure of the steering pump, or if the engine stops, there will be a loss of steering oil flow. Diverter spool (1) will move to the left. As long as the machine moves, the flow of oil from the secondary steering pump will provide oil for the steering operation.
The oil will flow through passage (3), past check valve (11), and through outlet (5). Check valve (8) will prevent the loss of flow through inlet (10) and the stopped steering pump.
When the machine moves in a reverse direction, the secondary steering pump turns in the opposite direction. The pressure oil from the pump is sent through passage (16) and (15) to left end of reversing spool (14) causing reversing 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 as when the machine moves forward.