RING-QUAD 1067546 - Caterpillar

Boom Raise Operation
Illustration 1 g06028136
(A) Pressure oil port from upper main control valve
(1) Boom cylinder
(2) Control valve
(3) Manual lowering valve
(4) Relief valve
(5) Pilot valve
(6) SpoolDuring a BOOM RAISE, oil from the main control valve flows to boom control valve (2). As the oil pressure increases, check valve inside pilot valve (5) and spool (6) shift. Oil passing through the check valve in valve (5) acts along with the spring on the left end of spool (6). The shift of the check valve in spool (6) allows oil to flow to the head end of the boom cylinders. The rod is extended and the boom raises. Spool (6) is spring biased to allow free flow into the cylinder, and to block flow from out of the cylinder.Boom Lower Operation
Illustration 2 g06028174
(B) Pressure oil port from upper main control valve
(1) Boom cylinder
(2) Control valve
(3) Manual lowering valve
(4) Relief valve
(5) Pilot valve
(6) SpoolWhen the operator moves the joystick to the BOOM LOWER position, pilot oil flows from the upper main control valve to Port (X). The pilot pressure moves pilot valve (5) to the right, which reduces pressure on the spring biased side of spool (6). Cylinder load pressure shifts spool (6) to the left and allows oil to flow out of the cylinder head end cavity to passage (A) and the main control valve.Oil from the head end of the boom cylinder now flows through to the main control valve. The boom cylinder rod retracts and the boom lowers.Manual Boom Lower
Illustration 3 g06028176
(A) Pressure oil port from upper main control valve
(1) Boom cylinder
(2) Control valve
(3) Manual lowering valve
(4) Relief valve
(5) Pilot valve
(6) SpoolAs manual shut off valve (3) is turned counterclockwise, the needle valve opens, and oil from the head end of the boom cylinder flows to the hydraulic tank. This flow allows the boom to lower. Oil also flows across the anti-cavitation check valves in the upper main control valve and into cylinder rod end port B.