TG4 / TC Rotary Shaft Oil Seals

TG4 oil seals—also known as TC oil seals, rotary shaft lip seals or skeleton oil seals—are the most widely specified radial seal for rotating equipment. The design combines a stamped steel outer case for press-fit retention, a rubber sealing element molded to the case, a primary sealing lip with a garter spring, and a secondary dust lip that excludes contamination from the sealing interface. This double-lip construction makes TG4/TC seals suitable for gearboxes, electric motors, pumps, compressors, wheel hubs and industrial axles where both fluid retention and particle exclusion are required. The TG4 designation is common in Asian and European supplier catalogs, while TC is the equivalent designation used by Parker, NAK and other major seal manufacturers. Both refer to the same geometry: a metal-cased double-lip rotary shaft seal with a spring-loaded primary lip. Our TG4/TC range is manufactured to ISO 6194 and DIN 3760 tolerances, with standard inside diameters from 20 mm to 210 mm and common cross-section widths of 7 mm, 8 mm, 10 mm and 12 mm. Shaft diameters outside this range, special widths and single-lip variants are available as custom orders. NBR is the standard lip material for TG4 seals in general industrial and automotive oil service. It provides excellent resistance to mineral oils, greases, water-glycol mixtures and hydraulic fluids from -40°C to +120°C. FKM is specified when operating temperatures rise above +120°C, when synthetic lubricants or fuels are present, or when aromatic hydrocarbons and acids would attack NBR. For each application we select the appropriate Shore A hardness—typically 70 or 75 Shore A for general service, and 80 to 90 Shore A for high-pressure or abrasive environments. Installation of TG4 seals requires a clean bore with a small lead-in chamfer and a shaft surface finish of approximately Ra 0.2–0.8 µm without circumferential machining marks. The seal should be pressed squarely into the bore until it seats against the housing shoulder. Lubricating the sealing lip and shaft before assembly prevents dry-start damage and extends service life. For high-speed applications, proper ventilation and heat dissipation should be considered to avoid lip hardening and cracking.