SHIM PACK 2V8369 - Caterpillar

Illustration 1 g03638244
Partial schematic, This schematic represents boom lower.
(1) Boom cylinders
(2) Boom lowering control valves
(3) Main control valve
(4) Manual boom lower
(5) Boom lowering PRV BOOM RAISE Operation
Illustration 2 g03638240
Boom lowering control valve
(6) Pilot supply line
(10) Supply line
(12) Drain line
(16) Passage
(19) Passage
(22) Passage
(23) Check valve
(24) Supply port
(25) Spool valve
(26) Drain port
(27) Passage
(28) Relief valve When the operator moves the joystick to the BOOM RAISE position, the pump oil flows from the main control valve through a line to port (10) of the boom lowering control valve. The pump oil flows into passage (16) and the pressure of the pump oil causes check valve (23) to shift downward against the spring. The pump oil flows through passage (16) to passage (19). This action allows pump oil to flow from port (10) to port (24) at the head end of the boom cylinders. The rods are extended and the boom raises.BOOM LOWER Operation
Illustration 3 g03638239
Boom lowering control valve
(6) Pilot supply line
(10) Supply line
(12) Drain line
(16) Passage
(19) Passage
(22) Passage
(23) Check valve
(24) Supply port
(25) Spool valve
(26) Drain port
(27) Passage
(28) Relief valve The oil in the rod end of the stick cylinder begins to flow to port (24) of the boom lowering control valve. As oil flows into passage (19), check valve (23) will remain closed. Simultaneously, pilot oil flow is provided to port (22) of the stick lowering control valve. The pilot oil at port (22) will cause spool (25) to shift to the left. The oil then flows from passage (24) to port (10). From port (10), the oil will flow through a line to the main control valve and back to the hydraulic tank.As the joystick is moved further to the BOOM LOWER position, the pilot pressure in port (22) increases. Spool (25) shifts further to the left which allows more oil from passage (19) to flow to passage (16). Oil from the head end of the boom cylinder now flows through port (24), to port (10), and then to the main control valve. The boom cylinder rod retracts and the boom lowers.When the joystick is returned to the NEUTRAL position, the loss of pilot oil pressure will allow the spring to force spool (25) to close. Oil in the rod end of the boom cylinder is trapped and the boom cylinders is held in position.Manual Boom Lower
Illustration 4 g03638237
Emergency valve group
(29) Port
(30) Seat
(31) Locknut
(32) Valve
(33) Ball
(34) Port As seat (30) is turned counterclockwise, ball (33) will shift. As ball (33) is shifted, oil is allowed to flow through port (29) and valve (32) to port (34). Oil from the head end of the boom cylinder flows through port (34) to the hydraulic tank. This action allows the boom to lower.Reference: For information on the location of the manual lower valve, see Operation and Maintenance Manual, "Equipment Lowering with Engine Stopped".