TUBE AS-AIR VENT 2W8442 - Caterpillar

Illustration 1 g00466462
Check valve (A) Inlet port (B) Outlet port (1) Valve spring (2) Spring chamber (3) Passage (4) Valve spool
Illustration 2 g00466464
Location of the check valve (6) Check valveCheck valve (6) is located on the boom and hook control valve below the floorplate in the operator's compartment. This valve prevents back pressure from the accumulator and the pilot circuit from entering the pressure reducing valve. Check valve (6) allows flow in only one direction. A pressure difference of 345 kPa (50 psi) is required to open the check valve.Oil from the pressure reducing valve enters the check valve through port (A). The oil applies pressure to spool (4). Spool (4) is kept closed by the force of spring (1) and back pressure from the valve outlet. The back pressure is felt through passage (3) into spring chamber (2) .Once the pressure in port (A) is approximately 345 kPa (50 psi) above the back pressure, spool (4) opens and oil exits through port (B). This oil charges the accumulator and pressure is supplied to the pilot circuit.