SEAL 2535021 - Caterpillar

Illustration 1 g00373832
Location of the Main Relief ValvesOne relief valve is not shown. (1) Implement pump. (2) Main relief valve.
Illustration 2 g00322843
Main Relief Valve (3) Oil inlet. (4) Valve. (5) Pilot valve. (6) Locknut. (7) Plunger. (8) Spring. (9) Spring. (10) Passage. (11) Oil outlet. There are three main relief valves. Each implement pump (1) has a relief valve (2). Each relief valve is installed in a manifold. Each relief valve is attached below each implement pump.The main relief valves are ahead of the other valves in the implement hydraulic system. The main relief valves are pilot-operated cartridge type valves. The pressure setting of each main relief valve is approximately 30400 kPa (4410 psi).The three main relief valves are identical. The three main relief valves operate identically.Implement system oil flows into inlet opening (3) through the orifice in the center of valve (4). The oil then flows into the chamber for spring (9). The oil in the spring chamber contacts pilot valve (5). When the oil pressure in the circuit is less than the relief valve setting, the relief valve is kept closed by the force of the pilot valve spring.If the oil pressure in inlet (3) and in the chamber for spring (9) achieves the relief valve setting, the oil will overcome the tension of spring (8). Pilot valve (5) is then moved to the right. When the pilot valve opens, the oil in the spring chamber flows past the open pilot valve. The oil then flows through passage (10) to the tank.When only the pilot valve is open, the force of spring (9) is acting on valve (4). The oil pressure in inlet (3) moves valve (4) far enough to the right so that implement oil can flow through the inlet opening. The oil can then flow through outlets (11) to the hydraulic tank. The oil pressure cannot increase to a pressure that is higher than the relief valve setting.The force of spring (8) keeps pilot valve (5) closed. If the force of spring (8) is changed, the relief valve pressure setting can be adjusted. In order to increase the pressure setting of the relief valve, loosen locknut (6) and turn plunger (7) clockwise. In order to decrease the pressure setting of the relief valve, loosen locknut (6) and turn plunger (7) counterclockwise.Turn plunger (7) clockwise by 1/4 turn in order to increase the relief valve pressure setting by 1275 kPa (185 psi). Turn plunger (7) counterclockwise by 1/4 turn in order to decrease the relief valve pressure setting by 1275 kPa (185 psi).