ALTERNATOR GP-CHARGING 2354178 - Caterpillar

Illustration 1 g03657642
(1) Swing parking brake
(2) Valve (swing parking brake)
(3) Line (pilot)
(4) Line (pilot for swing brake release)
(5) Displacement change valve for the right travel motor
(6) Displacement change valve for the left travel motor
(7) Line (pilot for two-speed travel)
(8) Pilot control valve (stick and swing)
(9) Pilot control valve (bucket and boom)
(10) Main control valve
(11) Swing control valve
(12) Boom control valve
(13) Passage (boom lower)
(14) Right travel control valve
(15) Left travel control valve
(16) Blade control valve
(17) Stick control valve
(18) Bucket control valve
(19) Auxiliary control valve
(20) Boom swing control valve
(21) Angle blade control valve
(22) Hydraulic activation solenoid valve
(23) Travel speed solenoid valve
(24) Center bypass
(25) Passage
(26) Pressure reducing valve
(27) Inline filter
(28) Passage
(29) Hydraulic lockout switch
(30) Two-speed travel relay
(31) Two-speed travel switch
(32) Passage
(33) Parallel feeder passage
(34) Passage
(35) Passage (boom raise)
(36) Signal line (load sense)
(37) Supply line
(38) Proportional pressure compensator
(39) Main pump
(40) Hydraulic tank
(41) Solenoid valves
(42) Pilot manifold
(43) Pilot control valve (travel)
(44) Pressure switch (travel)
(45) Pilot control valve (blade)
(46) Pressure switch (blade) Pilot Oil Circuit
Oil flow is supplied to the pilot system from main pump (39). The pilot system performs the following functions.
Reduce main system pressure to pilot pressure in order to operate the control devices.
Provide pilot oil pressure to travel pilot control valve (43), stick and swing pilot control valve (8), blade pilot control valve (45), and boom and bucket pilot control valve (9).
Provide pilot oil pressure to the swing brake control valve (2) and displacement change valves (6) and (5).Oil from main pump (39) flows through line (37) and into parallel feeder passage (33). The hydraulic oil flows from parallel feeder passage (33) to pilot manifold (42). Oil flows through pilot manifold (42), through passage (28), and into inline filter (27). The oil then flows into pressure reducing valve (26) and into passage (25). The oil in passage (25) divides into three paths. The first path is into center bypass (24). The second path is through travel speed solenoid valve (23). The third path is through hydraulic activation solenoid valve (22).When the boom swing function, the angle blade, or the auxiliary function is used, the pilot oil is directed by solenoid valves (41).The pressure within the pilot system is regulated by pressure reducing valve (26).Pilot Control Valve Circuits
When the hydraulic activation control lever is placed in the UNLOCKED position, hydraulic lockout switch (29) closes. This action activates hydraulic activation solenoid valve (22).The pilot oil flows through pilot manifold (42) to passage (28). Then, the oil flows to the following pilot control valves: stick and swing (8), bucket and boom (9), travel (43) and blade (45). When any of the pilot control valves are operated, the pilot oil flows to the selected valve within main control valve (10). The pilot oil shifts the stem of the selected control valve.Implement Circuit
Note: The following examples are for a BOOM LOWER and a BOOM RAISE function. A stick, bucket, swing, blade, or travel function have a similar operation.When the joystick for the boom is moved to the BOOM LOWER position, pilot oil from pilot control valve (9)