M312, M315, M318 and M320 Excavators Hydraulic System Relief Valve (Signal Limiter) Caterpillar


Relief Valve (Signal Limiter)
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M312, M315, M318 and M320 Excavators Hydraulic System [SENR6260]
HYDRAULIC SYSTEM
VALVE GP-RELIEF
M312, M315, M318 and M320 Excavators Hydraulic System Relief Valve (Line and Makeup)
M312, M315, M318 and M320 Excavators Hydraulic System Relief Valve (Signal Limiter)
1.1. Heavy Lift



Illustration 1g00814693



Illustration 2g00544128

Typical example

(1) Main relief valve

(2) Signal limiter relief valve

The load sensing signal limits the maximum system pressure. When the load sensing signal pressure is increased, the system pressure increases.

The relief valve for the load sensing signal controls the maximum load sensing pressure that is sent to the pump controls. During normal operation, the relief valve for the load sensing signal limits the load sensing signal pressure to a maximum of 31000 ± 500 kPa (4500 ± 75 psi).

When the load sensing signal pressure is greater than the pressure setting of the relief valve for the load sensing signal, the poppet is moved upward against the spring force. Load sensing signal pressure flows to the tank.

Heavy Lift

When heavy lift is activated, the solenoid valve for heavy lift on the pilot manifold is energized., Pilot hydraulic oil is sent to the top of the relief valve for the load sensing signal.

Pilot hydraulic oil pushes the spool in the downward direction, which compresses the spring in the relief valve for the load sensing signal. The maximum load sensing signal pressure is increased to 35500 to 36000 kPa (5150 to 5220 psi).

To adjust the maximum load sensing pressure, turn the adjustment nut inward or turn the adjustment nut outward.

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