MUFFLER AS 2090801 - Caterpillar

Illustration 1 g00874172
Pilot Valve (Oil Manifold) (1) Primary reducing valve. (2) Secondary reducing valve.The reducing valves are located in the pilot valve. The primary reducing valve regulates the pressure for the pilot oil system. The pressure in the pilot system is regulated for the proper pressure that is required in order to shift the spools in the main control valve. The secondary reducing valve is adjusted lower than the primary reducing valve. The secondary reducing valve is set for a pressure that is required to shift the spools in the main control valve, if the lift arms are raised and the engine is not running.
Illustration 2 g00873763
Pressure reducing valve (3) Locking nut. (4) Adjustment screw. (5) Housing. (6) Spring plunger. (7) Spring. (8) Poppet. (9) Tank port. (10) Regulated port. (11) Input port.Illustration 2 shows the flow of oil when the pressure at the inlet is below the pressure setting.Oil enters the reducing valve through input port (11). The oil flows into the bore in poppet (8). The oil that is flowing into the bore of the poppet flows through the regulated port. Poppet (8) has two sets of holes through the poppet. The lower set of holes are lined up with port holes (10). Regulated port (10) is a passage for the regulated oil. Poppet (8) is at a stationary position that is held by the force of spring (7). The pressure regulated oil flow is allowed to travel through the system. The pressure setting can be changed by loosening locking nut (3) and rotating adjustment screw (5). Spring plunger (6) moves inside housing (6). This will change the pressure setting of the reducing valve.
Illustration 3 g00873777
Pressure Reducing Valve (7) Spring. (8) Poppet. (9) Tank port. (10) Regulated port. (11) Input port.illustration 3 shows the flow of oil when the pressure at the inlet is above the pressure setting.In addition to the function of reducing pressure, this version of pressure reducing valve is a relieving valve. The pressure reducing valve is designed with an internal path to the hydraulic tank. If the pressure in the valve exceeds the pressure setting, the pressure reducing valve will open and oil can flow to the tank port. As the pressure at inlet port (11) begins to rise above the pressure setting, poppet (8) starts pushing against spring (7). When the pressure in the inlet is above the adjusted pressure, the poppet overcomes the force of the spring. The poppet moves in the housing. The upper row of holes in poppet (8) will be aligned with the tank port (9). The oil can flow to the hydraulic tank through tank port (9). When the oil pressure at port (11) is below the pressure setting, the oil can flow to regulated port 10.