TC FB TG4 NBR Double Lip Oil Seal Ring — Ø50–100mm Rotary Shaft Seals

Measure the shaft's inner diameter (ID), the bore's outer diameter (OD), and the housing depth (height). Match all three dimensions to the variant listed as ID × OD × Height. For example, a 70mm shaft in an 85mm bore with a 10mm housing depth needs the 70 × 85 × 10mm seal. When in doubt, measure twice — a seal that is even 1mm too large or too small will not seat correctly. Conversions: 50mm ≈ 1.97", 75mm ≈ 2.95", 100mm ≈ 3.94".

TC refers to the double-lip skeleton design with a metal reinforcement case. FB (Fully Bonded) means the rubber is bonded to the metal outer shell for a secure, leak-free press fit in the housing bore. TG4 is a lip geometry designation indicating a garter-spring-loaded primary lip, which maintains consistent radial contact force on the shaft as the lip wears over time — a key advantage over springless designs.

TC-type skeleton oil seals are generally designed for low-pressure dynamic sealing — typically up to 0.05 MPa (≈7 psi) of differential pressure. They are not intended for high-pressure hydraulic circuits. For higher-pressure applications, a lip seal with a backup ring or a different seal type is generally recommended. Contact us to confirm suitability for your specific pressure conditions.

The NBR compound offers good resistance to water, petroleum-based oils, and mild chemicals. The secondary dust lip provides additional protection against external contaminants, making these seals suitable for outdoor equipment such as agricultural machinery and construction equipment. For continuous submersion or exposure to aggressive chemicals (e.g., ketones, strong acids, or brake fluid), a Viton (FKM) seal is generally a better choice.

For best results, the shaft surface in the sealing zone should typically be ground or polished to Ra 0.2–0.8 µm (8–32 µin). Shaft hardness of HRC 45 or higher is generally recommended to minimize lip wear. Peripheral shaft speeds up to approximately 4–6 m/s are typically suitable for standard NBR TC seals, though this varies with operating temperature and lubrication conditions.

NBR is generally compatible with mineral-based engine oils, gear oils, ATF (automatic transmission fluid), and standard hydraulic oils. It is not recommended for use with synthetic esters, phosphate ester fluids, or brake fluids. If your application uses a fully synthetic PAO or ester-based lubricant, verify compatibility before installation or contact us for guidance.

Apply a thin film of clean grease or the retained fluid to the seal lip before installation. Use a seal driver or a flat press plate that contacts only the outer metal casing — never strike the rubber lip directly. Press the seal in squarely until the face is flush with or slightly below the housing bore face. Avoid driving the seal over keyways or splines without a protective installation sleeve to prevent lip damage.