Dipper ram seal kit JS (pre-2011) 903/20916 JCB JS, aftermarket

Dipper ram seal kit JS (pre-2011) 903/20916 is an aftermarket part for the JCB JS crawler excavators. According to the product card, the kit is for the dipper cylinder of JS excavators built before 24.10.2011.

The kit is chosen by the rod and bore diameters of the cylinder (for example 50 x 80 mm) and by cylinder type. Even two cylinders with the same diameters can have different seal profiles and groove sizes, so the kit is chosen by the cylinder's part number or the kit's own number. The number and shape of the parts depend on the gland and piston design of the cylinder.

Specifications

Compatibility

According to the product card, 903/20916 is a hydraulic cylinder seal kit. Fit is confirmed by the part number. Other parts are in Repair kits.

Fitting

Before the repair, disconnect the cylinder from the hydraulics, release the pressure and clean it outside, then dismantle it on a clean bench. Remove the old seals with plastic or brass tools so the grooves are not scratched. Wet the new seals with clean hydraulic oil and fit them the right way round; piston seals can be softened in warm oil if needed and sized with a calibrating sleeve. Pass the rod through the gland without damaging the seal and tighten the piston nut to the specified torque. After assembly, cycle the cylinder through full strokes a few times without load to purge air and check for leaks. After the first working day, grease the cylinder mounting pins and check the rod for any trace of oil.