320D3 and 323D3 Excavators Systems Caterpillar

Illustration 1	g06309818
(1) Inlet port (oil flow from pilot pump) (2) Pilot relief valve (3) Port (oil flow to hydraulic tank) (4) Outlet lines (regulated pilot oil pressure)

Pilot relief valve (2) is located on the mounting base for the pilot oil filter. The pilot relief valve limits the pressure in the pilot system. The pilot relief valve setting is adjustable.

The pilot oil flows from the pilot pump to inlet port (1). When the pressure in the pilot oil system reaches the pressure setting of pilot relief valve (2), part of the pilot oil flow is returned to the hydraulic tank through port (3). The pressure of the pilot system oil in outlet lines (4) is equal to the pressure setting of the pilot relief valve.

Reference: For more information concerning the pilot relief valve setting, refer to Testing and Adjusting, "Relief Valve (Pilot) - Test and Adjust".