GUARD AS-SENSOR 1G9514 - Caterpillar

Illustration 3 g00627797
Load check and flow compensator valve during load check (1) Load sensing signal from signal duplication valve (2) Load sensing signal to load signal control valve (3) Load check valve and compensator valve (4) Orifices (5) Feeder passage (6) Supply passage (7) True load signal to other circuits and signal duplication valve (8) Load signal from other circuitsThe control spool is moved slightly to the left. Implement carry pressure is directed around the control spool to the feeder passages. Implement carry pressure passes through the small orifices in the load check valve. Implement carry pressure then goes into the spring passage between the compensator piston and the load check valve. The load check valve is held down by the combination of the spring force and the force of the pressure.Operation During Flow Compensation
Illustration 4 g00786225
Load check and flow compensator valve during flow compensation (1) Load sensing signal from signal duplication valve (2) Load sensing signal to load signal control valve (3) Load check valve and compensator valve (5) Feeder passage (6) Supply passage (7) True load signal to other circuits and signal duplication valve (8) Load signal from other circuits (9) Return oil flow from implementAs the control spool shifts, pump flow goes through the throttling slots into the supply passage. The compensator piston and the load check valve will move up when the pump discharge pressure is higher than the implement carry pressure. The pump discharge pressure flows through the orifices in the load check valve to the feeder passage and to the implement. The true load signal from the feeder passage is also sent to the signal duplication valve. The signal duplication valve duplicates the true load signal from the feeder passage.The signal duplication valve sends the load sensing signal pressure to the spring chamber which is on top of the compensator piston. Load sensing signal pressure is also sent through the passage to the load sensing control spools in the pump regulator control valves in order to upstroke the pumps.During a stall condition or very slow implement movement, the load sensing control spool maintains pump discharge pressure 1860 kPa (270 psi) higher than the load sensing signal pressure. When the pump discharge pressure is higher than the load sensing signal pressure, the compensator piston will remain in the full open position.When another implement circuit is activated and a higher true load signal pressure occurs, the signal duplication valve will send a higher load sensing signal pressure to the compensator piston. The load sensing signal pressure oil on top of the compensator piston pushes the compensator piston downward. This decreases the oil flow that is passing from the supply passage through the orifices into the feeder passage.When the implement control levers are moved back toward the neutral position, the control spool will shift to the right. When the load sensing signal pressure decreases, the oil flow from the implement pumps decreases. The reduced load sensing signal pressure in the spring chamber on top of the compensator