SHIELD AS 8X5620 - Caterpillar

Illustration 2 g03877087
Left and right control valves
(1) Left control valve
(2) Port - lift cylinder head end
(3) Port - lift cylinder rod end
(4) Port - tilt cylinder head end
(5) Port - tilt cylinder rod end
(8) Lift cylinder line relief valve - head end
(9) Lift cylinder check valve - rod end
(10) Tilt cylinder line relief valve - head end
(11) Tilt cylinder line relief valve - rod end
(12) Right control valve
(17) Left raise solenoid valve
(18) Left rackback solenoid valve
(26) Right rackback solenoid valve
(27) Right raise solenoid valve
(28) Hydraulic lockout solenoid valve
(29) Left lowering solenoid valve
(30) Left dump solenoid valve
(31) Left float solenoid valve
(32) Right dump solenoid valve
(33) Right lowering solenoid valve
(39) Supply oil from left implement pump
(40) Supply oil from right implement pump The implement control valves are located in the front frame below the boom. When an implement is activated, oil from the implement control valve is directed to the lift cylinders and/or tilt cylinders.Tilt Control Valve HOLD Position
Illustration 3 g03087536
Section view - HOLD position
(1) Rackback solenoid
(2) Line relief valve
(3) Line relief makeup valve
(4) Dump solenoid
(5) Pilot oil chamber
(6) Tilt spool
(7) Tank port
(8) Valve passage
(9) Supply oil passage
(10) Internal passage In the HOLD position, pilot oil pressure is present at both ends of the control valve tilt spool. The pilot oil and the centering springs keep the lift spool in the centered position. The control valve lift spool blocks oil flow to the tilt cylinder, and oil from the tilt cylinder is blocked by the tilt spool. The oil is trapped and the cylinder will remain in the HOLD position.Oil from the implement pump enters the supply passage, flows around the tilt spool, and flows to the lift spool. The flow of oil through the lift control valve is similar to the flow of oil through the tilt control valve. However, the tilt control valve has priority over the lift control valve.The head end and rod end line relief valves limit the oil pressure in the head end and rod end of the tilt cylinder.Tilt Control Valve DUMP Operation
Illustration 4 g03087896
Section view - dump position
(1) Rackback solenoid
(2) Line relief valve
(3) Line relief makeup valve
(4) Dump solenoid
(5) Pilot oil chamber
(6) Tilt spool
(7) Tank port
(8) Valve passage
(9) Supply oil passage
(10) Internal passage When the operator moves the implement control lever to the DUMP position, the tilt lever position sensor sends a PWM signal to the implement ECM. Then the implement ECM sends current that energizes the dump pilot hydraulic actuator solenoid.The solenoid moves the spool for the pilot hydraulic actuator and the pilot oil at the right end of the tilt spool is drained to the tank. The pilot oil pressure on the left end of the tilt spool moves the tilt spool right to the DUMP position.The tilt spool directs oil from the implement pump to the load check valve. Oil flows through the load check valve and through the tilt spool to the rod end of the tilt cylinder. The tilt spool also opens the tank passages to allow the oil from the