CARRIER-PLANET 5S7880 - Caterpillar

Illustration 1 g00624441
Front Control Valve (1) Signal duplication valve (2) Load sensing signal relief valveWhen the implement and travel control levers are moved and the implements are stalled, the signal duplication valve and load sensing signal relief valve perform the following functions:
Send an equal pressure signal to the load sensing control spools in the six implement pump regulator control valves.
Send an equal pressure signal to the two margin relief valves.
The load sensing signal relief valve regulates the maximum pressure in the circuit.When the implement and travel control levers are partially moved and the implements are not stalled, the signal duplication valve and load sensing signal relief valve perform the following functions:
Send an equal pressure signal to the load sensing control spools in the six implement pump regulator control valves.
Send an equal pressure signal to the two margin relief valves.
Allow individual hydraulic circuits to operate at different pressures.
Determine hydraulic flow demand and signal the pump regulator control valves which regulate the pump flow.Load Signal Network and Signal Duplication Valve
The load signal network is a network of passages and shuttle valves between the implement and travel control spools and the signal duplication valve. The shuttle valves are more commonly known as resolver valves. The load signal network directs true load signal pressure from each control spool through the resolver valves. The true load signal pressure is the actual pressure which is present in the cylinder or the travel motor. The highest true load signal pressure will pass through the network to the signal duplication valve.The signal duplication valve minimizes the effects of leakage in the implement and travel circuits through the load signal circuit. The signal duplication valve reduces the pump discharge pressure in order to match the highest true load signal pressure. This reduced pump discharge pressure is called the load sensing signal pressure. Load Sensing Signal Circuit and Load Sensing Signal Relief Valve
The load sensing signal circuit directs the load sensing signal pressure to the load sensing control spools in the implement pump regulator control valves, the load sensing signal relief valve, the margin relief valves and the flow compensator valves.The load sensing signal relief valve limits the maximum load sensing signal pressure that is sent to the load sensing control spools in the implement pump regulator control valves, the margin relief valves and the flow compensator valves.Implement Actuated
Illustration 2 g00519269
Signal Duplication Valve and Load Sensing Signal Relief Valve with an Implement Actuated (1) Signal duplication valve (2) Load sensing signal relief valve (3) Signal duplication valve spool (4) Outer chamber (5) Orifice (6) Center passage (7) Chamber (duplicated load signal pressure) (8) Duplicated load signal pressure (9) Orifice (10) Passage (pump discharge pressure) (11) Highest true load signal pressure (12) Passage to drain (13) Load sensing signal pressure to the load sensing control spools in the implement pump regulator control valves (14) Load sensing signal pressure to the front control valve, rear control valve, and the margin relief valves (15) Travel signal pressure from the travel parking brake solenoid