PISTON 5371739 - Caterpillar

Illustration 1 g01073235
Pilot Manifold
(1) Accumulator
(2) Implement Pump Pressure Sensor
(3) Screen
(4) Pump Supply from End Cover
(5) Passage to Implement Return Oil
(6) Pilot Drain from Implement Control Valves
(7) Passage to Implement Control Valves (Pilot Supply)
(8) Pilot Filter
(9) Passage to Hydraulic Oil Tank
(10) Implement Lockout Valve
(11) Relief Valve
(12) Pressure Reducing Valve
(EE) Pneumatic Pressure
(FF) Activated Component
(GG) Tank Pressure
(KK) First Pressure Reduction
(QQ) Reduced Pilot Pressure
Illustration 2 g01073263
Pressure Reducing Valve
(13) Spring
(14) Passage to Hydraulic Oil Tank
(15) Passage from Implement Pump
(16) Pilot Pressure
(17) Spool
(18) Adjustment Screw Pressure reducing valve (12) is located in the pilot manifold. Pressure reducing valve (12) regulates the pressure of the pilot supply to a predetermined setting.Oil from the implement pump flows to the inlet manifold, through the valve stack, and through the end cover to the pilot manifold through passage (4). This oil supplies the pilot circuit. The pump oil passes through screen (3) before the oil enters the pressure reducing valve through passage (15).If pilot pressure (16) is lower than the pressure setting, the forces of spring (13) plus the pressure of the oil in passage (14) hold spool (17) to the right. In this position, pump supply oil is directed into the pilot circuit through the passage for pilot pressure (16).If pilot pressure (16) is higher than the pressure setting, the pressure of pilot pressure (16) shifts spool (17) to the left. Passage (15) is blocked and pilot pressure (16) is allowed to drain to the hydraulic tank through passage (14).Spool (17) is constantly shifting. Therefore, pressure reducing valve (12) is constantly metering in order to maintain the pilot supply pressure.The setting for pilot pressure can be adjusted with adjustment screw (18).