Caterpillar 5J-8300 U-Cup Rod Seal

Caterpillar 5J-8300 U-Cup Rod Seal is a urethane U‑cup seal used to seal hydraulic cylinder rods in Cat equipment, serving as the primary rod sealing element in Caterpillar cylinder assemblies. The part number is 5J-8300 and it is molded in URE material, categorized as a U‑cup rod seal. Dimensions listed for this part are A = 0.41 in (10.49 mm) and B = 3.50 in (88.95 mm). As a Caterpillar replacement component, it is designed to fit the original packing profile and help prevent hydraulic fluid leakage as the rod moves within the cylinder. The U‑cup design provides a simple, robust sealing solution suited to the hydraulic systems used in heavy equipment, with material and geometry chosen to resist wear and provide reliable sealing across demanding operating conditions.