HARNESS AS-PUMP 3410134 - Caterpillar

The main control valve is located in the hydraulic system between the main pump and the actuators (cylinders and motors). According to the machine operation, components in the main control valve control the flow of pump oil. The components also control the pressures in the circuits for the right pump (17), left pump (18), swing pump (20), and pilot pump (19). In this way, the operating speed and directions of the cylinders and motors are changed, and the pressure of the pump oil is controlled.Operation and Functions
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Main control valve (1) Return port (2) Boom II control valve (3) Blade control valve (4) Flow switching valve (5) Stick control valve (6) Inlet port (right pump) (7) Right travel control valve (8) Return port (9) Bucket control valve (10) Inlet port (swing pump) (11) Boom swing control valve (12) Swing control valve (13) PTO control valve (14) Left travel control valve (15) Inlet port (left pump) (16) Boom I control valveThere are eleven major valves in the main control valve. Oil is directed from the pumps to these valves in the following manner:Oil from the right pump (17) enters the main control valve through inlet port (6) and the oil flows to the bucket control valve (9), boom I control valve (16), and right travel control valve (7) .Oil from the left pump (18) enters through inlet port (15) and the oil flows to the left travel control valve (14), stick control valve (5), and the PTO control valve.Oil from the swing pump (20) enters through inlet port (10). The oil flows to boom II control valve (2). boom swing control valve (11), blade control valve (3), and swing control valve (12) .The major valves in the main control valve have the following functions:Control in the NEUTRAL position - When the joysticks are in the NEUTRAL position, oil passes through the center bypass passage in the main control valve. The oil is exhausted through return ports (1) and (8) .Operation of individual valves - Individual valves are used in extending the cylinder rods and retracting the cylinder rods. These valves are also used to actuate the hydraulic motors. Pump oil is supplied to the valves through the center bypass passage and the parallel feeder passages.Prevention of leakage and drift in cylinders and motors - This function is performed through the use of load check valves.Release of the swing brake - Oil under pressure is required to release the swing brake.Limitation of circuit pressure - This function is performed through the use of relief valves.Changeover from single flow to combined flow - The oil supply to the PTO (power take-off) can be changed to single flow or combined flow. Oil for single flow operations is provided by the swing pump. Oil for combined flow operations is provided by the left pump and the swing pump.Straight travel - The straight travel control enables the machine to continue straight travel even though an implement or the PTO is used.Individual Valve Operation
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Bucket