Dual Set Crossover Relief Valve
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| Illustration 1 | g03323491 |
Pressure circuit for SWING RIGHT operation (partial schematic) (1) Makeup line (2) Swing motor (3) Passage (supply oil) (4) Makeup port (5) Motor rotary group (6) Passage (return oil) (7) Relief valve (8) Swing energy recovery valve (9) Port (supply oil) (10) Check valve (11) Check valve (12) Port (return oil) (13) Check valve (14) Return passage (15) Slow return check valve (16) Swing IMV control valve (17) Line (18) Selector spool (19) Passage (20) Dual set crossover relief valve (21) Passage (22) Port (23) Return line (24) Swing relief solenoid valve | |
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| Illustration 2 | g02849276 |
Swing energy recovery valve (7) Relief valve (8) Swing energy recovery valve (20) Dual set crossover relief valve | |
Relief valves (20) and (7) are located in swing energy recovery valve (8) . Dual set crossover relief valve (20) limits the pressure in the left and right swing circuits to the swing relief valve setting. This action provides a cushion effect at a start or stop of the swing operation. Relief valve (7) limits the pressure in the swing accumulators.
When the swing joystick is returned to the NEUTRAL position during the swing right operation, the swing pump-to-motor spool and motor-to-tank spool shifts to the NEUTRAL position. Since the swing spools are in the NEUTRAL position, the oil delivery through port (9) to the motor rotary group (5) is now blocked at swing IMV (16) . The return oil from the motor rotary group through port (12) is also blocked at swing independent metering valve (16) .
The mass (weight and size) of the upper structure causes the upper structure to attempt to continue to rotate after the swing joystick is returned to the NEUTRAL position. The motor rotary group is also attempting to continue to rotate. The motor rotary group attempts to draw oil through port (9) and attempts to displace the oil through port (12) .
The oil supply to motor rotary group (5) is insufficient. A vacuum condition occurs in passage (3) . Return oil is supplied to the motor rotary group as makeup oil in order to prevent the vacuum condition. For more information concerning the makeup operation, refer to Systems Operation, "Oil Makeup (Swing System)".
Since the flow of return oil from the motor rotary group through port (12) is blocked at swing independent metering valve (16) , the pressure of the blocked oil in passage (6) increases. The increased oil pressure in passage (6) flows to swing energy recovery valve (8) , selector spool (18) , and acts on dual set crossover relief valve (20) .
Swing Relief Solenoid Valve ON
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| Illustration 3 | g02867676 |
Dual set crossover relief valve (CLOSED) (19) Passage (22) Port (25) Valve (26) Spring chamber (27) Spring (28) Valve (29) Spring (30) Passage (31) Orifice (32) Return passage (33) Passage (34) Chamber (35) Piston (36) Passage | |
When swing relief solenoid valve (24) is activated by the machine ECM, pilot oil flows from the pilot pump through solenoid (24) , line (17) , and port (22) . Pilot oil enters passage (36) which forces piston (35) to shift to the left which causes a higher spring force on valve (28) . A higher pressure is now needed to open dual set crossover relief valve (20) . The larger pressure results in a greater overall system pressure. The greater system pressure allows more pressure in the swing circuit for better control when the swing accumulators discharge.
OPEN Position (Swing Relief Solenoid Valve ON)
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| Illustration 4 | g02869142 |
Dual set crossover relief valve (OPEN) (19) Passage (25) Valve (26) Spring chamber (27) Spring (28) Valve (29) Spring (30) Passage (31) Orifice (32) Return passage (33) Passage (34) Chamber | |
Oil pressure in passage (19) nears the relief pressure setting. Oil pressure in passage (19) overcomes the force of spring (29) . The oil pressure opens valve (28) . The oil in valve chamber (34) goes through passage (33) to return passage (32) . The oil is called low-pressure oil. The oil pressure from passage (19) decreases at orifice (31) . The oil then goes through spring chamber (26) to valve chamber (34) . Because of the decreased oil pressure in spring chamber (26) , the oil pressure from passage (19) pushes valve (25) to the right against the force of spring (27) . Passage (30) now opens allowing the high-pressure oil flow from passage (19) to return passage (32) .
CLOSED Position (Swing Relief Solenoid Valve OFF)
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| Illustration 5 | g02868938 |
Dual set crossover relief valve (CLOSED) (19) Passage (25) Valve (26) Spring chamber (27) Spring (28) Valve (29) Spring (30) Passage (31) Orifice (32) Return passage | |
When main pump oil pressure in passage (19) is less than the main relief pressure setting, valve (25) and valve (28) are closed by the force of spring (27) and spring (29) . The oil in passage (19) goes through orifice (31) . Oil enters spring chamber (26) . The pressure in passage (19) and the pressure in spring chamber (26) are equal. Valve (25) shifts left by the force of spring (27) . Valve (25) closes passage (30) . There is no oil flow from passage (19) to return passage (32) .
Note: If the machine ECM activates an event code related to the swing hybrid system, the machine ECM will de-energize swing relief solenoid valve (24) . The machine ECM will also disable the swing energy recovery valve. This action allows the machine to operate without the swing hybrid system.