HOOD A.-LH 1H1122 - Caterpillar

Illustration 1 g00473674
Line relief valve (closed position) (1) Passage (2) Valve (3) Valve (4) Spring chamber (5) Valve (6) Spring (7) Piston (8) Return passage (9) PassageHigh pressure oil which is between the cylinder and the control valve flows through passage (1). High pressure oil enters the line relief valve. The oil then flows through passage (9), through the opening of piston (7) and into spring chamber (4). If the oil pressure is less than the line relief valve pressure setting, valve (5) will remain closed by the force of spring (6). This equalizes the oil pressure in passage (1) and spring chamber (4). One surface of valves (2) and (3) face the spring chamber. One surface of valves (2) and (3) face the cylinder passage. The surface that faces the cylinder contains more surface area. Valves (2) and (3) are shifted all the way to the left. Valves (2) and (3) are held in position. The oil flow from passage (1) is now blocked to return passage (8).
Illustration 2 g00473675
Line relief valve (open position) (1) Passage (3) Valve (4) Spring chamber (5) Valve (6) Spring (7) Piston (8) Return passage (9) Passage (10) Valve chamber (11) Passage (12) PassageThe oil pressure in passage (1) increases to the relief valve setting. Valve (5) shifts