Bucket ram seal kit JS330 903/21071 JCB JS, aftermarket

For the JCB JS crawler excavators: bucket ram seal kit JS330 903/21071, an aftermarket part. According to the product card, the kit is for the bucket cylinder of the JS330 built before 01.02.2011.

The main signs that the seals need changing are an oil ring on the rod and drips from the gland, the boom or dipper creeping down under load (internal leakage past the piston seal) and slower movements. A leaking cylinder lowers the tank level, and dust getting in wears both the seals and the pump and valves. Seal replacement should therefore not be put off.

Specifications

Compatibility

According to the product card, 903/21071 is a hydraulic cylinder seal kit. Fit is confirmed by the part number. Other parts are in Repair kits.

Fitting

No sharp tools are used when fitting the seals: fold the seal slightly into a kidney shape, insert it in the groove and ease it into place by hand. Fit the rod seal and wiper in the gland grooves the right way round, as a reversed seal leaks at once under pressure. Cover the rod threads and edges with a thin protective sleeve or tape as they pass through the gland. After assembly, test the cylinder first without load, then under load, and check the seal area again after a day's work. After the first working day, grease the cylinder mounting pins and check the rod for any trace of oil.