193-8481 1938481 Cylinder Overhaul Seal Kit for Mini Excavator 304.5 305.5 306

Q: What four differentiated raw materials compose all sealing spare parts inside this swing cylinder repair kit?
A: The whole kit is constructed from high abrasion-resistant cast PU main dynamic seals, talc mineral modified anti-extrusion PTFE back-up rings, hydrolysis-stable HNBR rubber static sealing pieces and cotton woven cloth resin-soaked wear-resistant guide rings for piston supporting.

Q: What is the original natural color of each material seal without extra artificial pigment or surface coating?
A: Cast PU sealing rings are clean ivory white, talc-filled PTFE back-up parts are pale ash grey, HNBR rubber fittings are uniform matte black, cotton base fabric wear rings are light ginger brown tone.

Q: What core sealing task does cast PU finish inside mini excavator swing motor cylinder?
A: As the primary reciprocating sealing component, cast PU depends on outstanding compression resilience to block high-pressure hydraulic oil leakage when swing cylinder drives upper machine body to rotate left and right continuously during frequent spot excavation and material shifting on tight construction plots.

Q: Why is talc compounded PTFE matched as auxiliary back-up ring behind PU main seal for swing cylinder structure?
A: It fills tiny assembly clearances in piston grooves and effectively prevents soft PU seal edge from being squeezed and ruptured under instant hydraulic pressure surge generated by sudden swing rotation load change when mini digger hits hard underground stones or compact soil.
Q: What unique functional merits make HNBR superior over ordinary NBR rubber for swing cylinder static sealing positions?
A: HNBR owns excellent anti-hydrolysis and anti-ageing performance, keeping stable sealing tightness after long-time contact with aged high-temperature hydraulic fluid and intermittent muddy water splashing at outdoor open-air construction environments all year round.

Q: At which fixed static installation spots of swing motor cylinder do HNBR rubber seals get assembled?
A: HNBR components are mainly fitted for flange sealing of swing cylinder end caps and threaded connector gaps of auxiliary oil passages, stopping invisible slow oil seepage at stationary assembly joints exposed to outdoor dust and moisture.

Q: What supportive function can cotton base resin impregnated wear fabric realize for swing cylinder reciprocating piston?
A: It bears partial lateral radial load of moving piston during swing rotation stroke, corrects minor piston offset and lowers metal friction loss between piston outer circle and inner cylinder bore wall to extend overall seal service cycle.