HOSE AS 2186637 - Caterpillar

Illustration 1 g00869695
Cross Section View of the Main Relief Valve
Illustration 2 g00869710
Oil FlowOil enters the main relief valve at pressure port (1). The oil flows through orifice (13) and the oil flows through the opening in poppet (2). When the oil pressure in cavity (14) exceeds the force of spring (10), poppet (8) moves off seat (7). When the poppet moves off the seat the oil flows through port (9) and out of the relief valve.
Illustration 3 g00869708
The oil pressure in cavity (14) will drop to low pressure. Poppet (2) will overcome the force of spring (6). Poppet (2) will move and poppet (2) will seat against poppet (8). No oil can flow back to the hydraulic tank. This will cause a decrease in pressure within cavity (14).
Illustration 4 g00869742
When the pressure within the oil cavity decreases, the pressure on relief valve poppet (5) is greater than the pressure in oil cavity (14). Relief valve poppet (5) will move off seat (4). The oil that is above the adjusted pressure is allowed to drain to the hydraulic tank through low pressure port (3). The pressure in the main hydraulic system stays at the adjusted value or below the adjusted value.The adjustment for the pressure setting is done by loosening locking nut (12) and turning adjuster (11).