Front control valve 25/222578 JCB 3CX/4CX, genuine

Front control valve 25/222578 is a genuine JCB part for the JCB 3CX and 4CX backhoe loaders.

The front (loader) control valve controls the raising and lowering of the backhoe loader's front arms and the crowd and dump of the shovel; on machines with a multi-purpose shovel the clam line is fed from this block too. Husco makes the control valves of JCB backhoe loaders, and this block is supplied as a genuine part under the JCB number. The catalogue also lists a similar loader valve as an OEM Husco version. As the clearance between spool and body wears, internal leakage grows: the arms drop under load, the shovel tips and the services slow. External leakage from the spool seals leaves oil under the lever. Check the cylinder seals and relief valves before replacing the block, since they can give the same symptoms. The block is heavy; lift it with two people or a hoist. The genuine block comes with the spool configurations and factory pressure settings specified by JCB. The block is chosen by part number, and its section count, port layout and linkage connections are compared with the old block.

Specifications

Compatibility

The OEM Husco loader valve in the catalogue: 25/222579. Other parts are in Hydraulic control valves.

Fitting

Before removing the block, label the hoses and pipes, release the pressure and disconnect the control linkage. Put the new block on a clean surface, make the connections with new O-rings and tighten the mounting bolts evenly, since overtightening distorts the body and can jam the spools. Adjust the linkage so the spools sit exactly central in neutral and make a full stroke. On first start, slowly run every function through its full stroke to bleed the air and measure the main relief pressure with a gauge.