TUBE AS 1215351 - Caterpillar

CLOSED Condition
Illustration 1 g02140504
Line relief valve (CLOSED position)
(1) Passage
(2) Piston
(3) Valve
(4) Valve
(5) Spring chamber
(6) Valve
(7) Spring
(8) Return passage
(9) Passage
(10) Spring
(11) Spring The high pressure between the cylinder and the control valve is transmitted to passage (1). This oil pressurizes the line relief valve. The pressure oil flows from passage (1) through passage (9) of piston (2). The oil then flows into spring chamber (5). When the oil pressure is lower than the line relief valve pressure setting, valve (6) remains in the CLOSED position by the force of spring (7). The oil pressure in passage (1) and the oil pressure in spring chamber (5) are equal. Spring (10) and spring (11) force piston (2), valve (3), and valve (4) to the left. The high-pressure oil is not able to flow from passage (1) to return passage (8). The high pressure between the cylinder and the control valve is maintained.OPEN Condition
Illustration 2 g02140505
Line relief valve (OPEN position)
(1) Passage
(2) Piston
(4) Valve
(5) Spring chamber
(6) Valve
(7) Spring
(8) Return passage
(9) Passage
(10) Spring
(11) Spring
(12) Spring chamber
(13) Passage
(14) Passage As pressure spikes occur in the line between the cylinder and the control valve, the oil pressure is momentarily higher in passage (1) than spring chamber (5). Piston (2) and valve (4) are forced to the right against spring (10) and spring (11). high-pressure oil is able to flow from passage (1) to passage (14), and to return passage (8) which relieves the pressure spike.high-pressure oil flows through passage (9) into spring chamber (5). Because the high-pressure oil is equal on the left side and the right side of piston (2) and valve (4), spring (10) and spring (11) force piston (2) and valve (4) to the left which closes the flow of oil from passage (1) to return passage (8).When the high-pressure oil in passage (1) and spring chamber (5) reaches the line relief valve pressure setting, valve (6) overcomes the force of spring (7) and shifts to the right. When valve (6) shifts to the right, high-pressure oil flows from spring chamber (5) to spring chamber (12), to passage (13), and then to return passage (8). The high-pressure oil in passage (1) becomes low pressure. The low-pressure oil is not high enough to overcome the force of spring (7). Valve (6) shifts to the left which stops the flow of oil from spring chamber (5) to spring chamber (12).Makeup Condition
Illustration 3 g02140506
Line relief valve (makeup operation)
(1) Passage
(3) Valve
(4) Valve
(5) Spring chamber
(8) Return passage
(9) Passage
(13) Shoulder The line relief valve functions as a makeup valve in the following manner:When oil from one end of the cylinder is discharged through the line relief valve,