VALVE GP-PRESSURE REDUCING 4T5017 - Caterpillar

Illustration 1 g03506198
Pilot oil manifold
(1) Pilot oil manifold
(2) Hydraulic activation solenoid valve
Illustration 2 g03508655
Cab
(3) Hydraulic activation control lever (LOCKED position)
Illustration 3 g03508838
Cab
(3) Hydraulic activation control lever (UNLOCKED position)
Illustration 4 g03509090
(3) Hydraulic activation control lever
(4) Plunger
(5) Bar
(6) Limit switch Limit switch (6) and plunger (4) are located on a bracket with hydraulic activation control lever (3). The limit switch is activated by hydraulic activation control lever (3).When hydraulic activation control lever (3) is shifted to the LOCKED position, solenoid valve (2) of pilot oil manifold (1) is not energized. Pilot oil is not supplied to the pilot control valves. Thus when the joysticks and/or the travel levers/pedals are operated, the cylinders or the motors are not activated. The engine will not start unless hydraulic activation control lever (3) is in the LOCKED position. If some one unexpectedly operates the machine, the machine will not operate.When hydraulic activation control lever (3) is placed in the UNLOCKED position, solenoid valve (2) is energized and pilot oil passes through the solenoid valve. Pilot oil now flows to the pilot control valves.
Illustration 5 g01435987
Partial diagram of solenoid valve (hydraulic activation) (UNLOCKED circuit)
(2) Hydraulic activation solenoid valve
(7) Solenoid
(8) Spring
(9) Spool
(10) Control valve
(11) Passage
(12) Passage
(13) Passage
(14) Passage (return oil)
(15) Passage (pilot oil to swing brake solenoid valve)
(16) Swing brake solenoid valve
(17) Passage (pilot oil flow to pilot valves/joysticks)
(18) Valve (hydraulic activation)
(19) Passage When hydraulic activation control lever (3) is placed in the UNLOCKED position, plunger (4) of limit switch (6) is depressed by control lever (3). Limit switch (6) is in the ON state.The hydraulic activation solenoid valve (2) 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) opens. Pilot pressure oil from passage (13) flows through passage (11) and to valve (18). The spool in valve (18) moves in a downward direction. Pilot pressure oil in passage (19) flows through valve (18). Pilot oil is now delivered through passage (15) to swing brake solenoid valve (16). Pilot pressure oil in passage (19) is also delivered to the pilot control valves (joysticks and travel levers/pedals) through passage (17).
Illustration 6 g03028976
Partial drawing of solenoid valve (hydraulic activation) (LOCKED position)
(1) Hydraulic activation solenoid valve
(7) Solenoid
(8) Spring
(9) Spool
(11) Passage
(12) Passage
(13) Passage
(14) Passage (return oil)
(20) Passage When hydraulic activation control lever (3) is moved to the LOCKED position, plunger (4) of limit switch (6) is not depressed by control lever (3). Limit 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) is forced upward by spring (8). Passage (20) opens and passage (12) closes. Passage (13) is not open to passage (11). Pilot oil supply to passage (17) is stopped. Pilot oil supply to the pilot control valves (joysticks and travel levers/pedals) is blocked. The cylinders and the motors cannot be activated.