INDICATOR GP 2850898 - Caterpillar

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Pilot oil manifold (1) Hydraulic activation solenoid valve
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Cab (3) Hydraulic activation control lever (LOCKED position)
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Cab (3) Hydraulic activation control lever (UNLOCKED position)
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Partial diagram of pilot oil manifold (2) Pilot oil manifold (9) Pilot relief valve (24) Passage (pilot system oil) (25) Valve
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Hydraulic activation control lever (LOCKED position) (3) Hydraulic activation control lever (4) Lever (5) Plunger (6) Limit switchWhen hydraulic activation control lever (3) is shifted to the LOCKED position, hydraulic activation solenoid valve (1) of pilot manifold (2) is not energized. Because solenoid valve (1) is closed, pilot oil is not supplied to the main control valve or the swing control valve. Thus when the joysticks and/or pedals are operated, the cylinders and the motors are not activated. Limit switch (6) is mounted to hydraulic activation control lever (3) .The engine does not start unless hydraulic activation control lever (3) is in the LOCKED position. If someone unexpectedly attempts to operate the machine, the machine will not operate.When hydraulic activation control lever (3) is shifted to the UNLOCKED position, pilot oil passes through solenoid valve (2) and flows to the main control valve and the swing control valve.
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Partial diagram of hydraulic activation solenoid valve (UNLOCKED circuit) (1) Hydraulic activation solenoid valve (7) Solenoid (8) Spring (9) Spool (10) Control valve (11) Passage (12) Passage (13) Passage (15) Line (pilot oil to swing parking brake solenoid valve and swing control valve) (16) Line (pilot oil to main control valve) (17) Line (pilot oil to main control valve) (18) Passage (oil flow to hydraulic tank) (19) Valve (20) PassagePlunger (5) of limit switch (6) is mounted to the hydraulic activation control lever. See Illustration 5. When the plunger is depressed by lever (4), switch (6) is in the ON state.The hydraulic activation solenoid valve (1) consists of solenoid (7) and control valve (10). When hydraulic activation control lever (3) is in the UNLOCKED position, solenoid (7) controls valve (10). When solenoid (7) is energized, spool (9) moves in a downward direction against the force of spring (8). Passage (12) is opened so that pilot pressure oil from passage (13) acts on valve (19) through passage (11). Valve (19) moves in a downward direction. Pilot pressure oil in passage (20) flows through valve (19). Pilot oil is now delivered to the swing control valve and the swing parking brake through line (15). Pilot pressure oil in passage (20) is also delivered to the main control valve through lines (16) and (17).
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Partial drawing of hydraulic activation solenoid valve (LOCKED position) (1) Hydraulic activation solenoid valve (7) Solenoid (8) Spring (9) Spool (11) Passage (12) Passage (13) Passage (18) Passage (oil flow to hydraulic tank) (21) PassageWhen hydraulic activation control lever (3) is shifted to the LOCKED position, plunger (5) of limit switch (6) is not in the retracted position. Therefore, switch (6) is in the OFF state.When hydraulic activation control lever (3) is in the LOCKED position, solenoid (7) is not energized. Spool (9)