A seal kit is only useful when it matches the cylinder’s current internal geometry, fluid and operating temperature. Two cylinders with the same bore and rod diameter may have different gland grooves, piston designs or material requirements. A generic kit can create a new leakage problem.
Why bore and rod size are insufficient
A nominal 100 mm bore and 60 mm rod do not identify the piston seal groove, gland depth, backup rings or bearing arrangement. Changes in production revision or fluid may alter materials while the external dimensions stay the same. Parker’s cylinder service resources list seal kits by series and parts identification, illustrating why kit selection needs more than a pair of diameters. Start with serial number, drawing revision and the kit list approved for the installed cylinder.
Parker’s cylinder safety and service materials link seal failure to bearing wear, damaged surfaces and fluid incompatibility. A repair plan should therefore identify the cylinder serial number and drawing revision, then inspect the rod, gland, bore and guides before opening a kit. Store seals with their material identification and approved shelf-life information from the supplier. After assembly, record part numbers, measured clearances and the pressure or leakage checks that were actually performed. The precise test limits come from the relevant cylinder specification, not from a universal pass number.
Use the failed parts as evidence
Before discarding the old seals, note which lip failed, the direction of extrusion, uneven wear, hardening or chemical swelling. Inspect rod finish, gland groove, bushing clearance and bore condition. A seal that extrudes may point to pressure or gap conditions; a torn wiper may indicate external debris; a chemically softened part may point to the fluid. The observations guide whether a simple kit replacement is enough or the rod, guide or operating conditions must change. Photograph and label parts in removal order.
A repeat-failure example
A rolling-line cylinder receives the same seal kit twice in one year. The second failure again shows one-sided wear and metal particles in the gland. A third identical kit is unlikely to solve it. Measure bushing clearance, rod straightness and mounting alignment, and examine the fluid sample for abrasive debris. Keep the failed seals labeled by cylinder side and orientation so the wear pattern survives disassembly. If a new guide or seal material is approved, record the revised kit number and drawing revision in the service system. Otherwise, a future technician may unknowingly repeat the old repair.
Close the repair record
Record the installed part numbers and materials, the fluid, measured clearances, assembly instructions followed and the test performed after repair. Preserve the pressure and leakage result with the cylinder serial number. Store spare kits with supplier identification and expiry or shelf-life instructions, protected from heat, light and contamination as specified by that supplier. If the repair changes the seal design, revise the parts list and approved drawing so the next technician does not unknowingly revert to the old arrangement.
Checks to put on the drawing or test plan
- Match the kit to serial number, groove dimensions and drawing revision.
- Confirm seal material compatibility with the actual oil and temperature.
- Record failed-part observations and post-repair test evidence.
Failure mode to avoid: Replacing seals without checking a worn bushing or scratched rod can quickly destroy the new kit.
Information to request before approval
- Cylinder ID and approved drawing.
- Fluid and temperature history.
- Failed seal photos and measured bearing condition.
For a related explanation, see rod bushing inspection guide.
Références techniques : Parker Cylinder Safety Guide; Parker cylinder service resources. The cited manuals and product data describe their makers’ equipment; this article is independent engineering guidance and does not assign their ratings to Yongjian products.