PLATE AS 5008542 - Caterpillar

Illustration 1 g06262662There are two line relief valves located within the tilt circuit. The line relief valve is installed to regulate the pressure spikes. The pressure can spike from either the implement pump or any unusual outside forces acting on the work tool. When the pressure is higher than the setting of the line relief valve, the relief valve opens. This process allows the pressure spike to return to the hydraulic tank. This process will prevent high pressure from damaging any components in the hydraulic system.
Illustration 2 g06074967
Line relief valve
(1) Inlet
(2) Tank passage
(3) Cavity
(4) Poppet
(5) Tank passage
(6) Spring
(7) Makeup spool
(8) Valve
(9) Dump spool
(10) Spring
(11) Cavity
(AA) Supply oil
(BB) Tank oil
(CC) Active components
(DD) Surface areaIllustration 2 shows a line relief valve with the pressure at inlet (1) below the adjusted pressure of the valve.
Illustration 3 g06074972
Line relief valve
(1) Inlet
(2) Tank passage
(3) Cavity
(4) Poppet
(5) Tank passage
(6) Spring
(7) Makeup spool
(8) Valve
(9) Dump spool
(10) Spring
(11) Cavity
(AA) Supply oil
(BB) Tank oil
(CC) Active components
(DD) Surface area
(EE) Reduced supply pressureIllustration 3 shows a line relief valve with the pressure at inlet (1) that is starting to rise above the adjusted pressure of the valve. As the pressure begins to rise, the oil that is flowing into inlet (1) will shift valve (8) to the right. High-pressure oil flows past valve (8) into cavity (3). The oil pressure in cavity (3) works against the area of poppet (4). The force that is developed on the area around the end of poppet (4) overrides the force of spring (6). Poppet (4) shifts to the right.
Illustration 4 g06074975
Line relief valve
(1) Inlet
(2) Tank passage
(3) Cavity
(4) Poppet
(5) Tank passage
(6) Spring
(7) Makeup spool
(8) Valve
(9) Dump spool
(10) Spring
(11) Cavity
(AA) Supply oil
(BB) Tank oil
(CC) Active components
(DD) Surface area
(EE) Reduced supply pressureWhen poppet (4) shifts to the right, the pressure in cavity (3) will decrease. The pressure on the end of valve (8) overrides spring (10). Then, dump spool (9) moves toward the right. The flow of oil that is needed to lower the pressure at inlet (1) is allowed to flow out of tank passage (2).When the pressure at inlet (1) is less than the adjusted pressure, the force of spring (6) moves poppet (4) to the left. Poppet (4) will seat. Then, the combination of the pressure in cavity (3) and the spring force from spring (10) moves dump spool (9) left against the seat. The flow of oil to tank passage (2) is blocked, during this time.Makeup Valve
The line relief valve can be used as a makeup valve. The tilt cylinder is moving and the pump cannot supply the amount of oil that is needed to fill the void in the cylinder. Oil through the makeup valve is available to help with filling the void.
Illustration 5 g06074986
(1) Inlet
(7)