TRANSMISSION 2990321 - Caterpillar

Illustration 1 g06199238
Main control valve
(1) Solenoid manifold
(2) Hydraulic lock solenoid valve
Illustration 2 g06199231
Cab
(3) Hydraulic activation control lever (LOCKED position)
Illustration 3 g06199232
Cab
(3) Hydraulic activation control lever (UNLOCKED position)
Illustration 4 g06199250
(3) Hydraulic activation control lever
(4) Limit switch lever
(5) Bar
(6) Limit switchLimit switch (6) and lever (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 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 g06199316
Partial diagram of solenoid valve (hydraulic activation) (UNLOCKED circuit)
(2) Hydraulic lock solenoid valve
(7) Passage (pilot oil to valve)
(8) Passage (pilot oil flow to pilot valves)
(9) Passage (return oil)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.When hydraulic activation control lever (3) is in the UNLOCKED position, solenoid (2) controls the hydraulic lock valve. When solenoid (2) is energized, the spool moves. Passages (7) and passages (8) open. Pilot pressure oil from passage (7) flows through passage (8). Pilot oil is now delivered through passage (8) to the pilot control valves.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 (2) is not energized. Passage (9) opens and passage (7) closes. Passage (7) is not open to passage (8). Pilot oil supply to passage (8) is stopped. Pilot oil supply to the pilot control valves is blocked. The cylinders and the motors cannot be activated.