TC Oil Seal NBR Rotary Shaft Seal Shaft Double Lip Metric Size Rotary Shaft

Measure three dimensions: the shaft outside diameter (this becomes the seal's inside diameter), the housing bore diameter (this becomes the seal's outside diameter), and the groove depth. Cross-reference all three against the variant options listed above. If the shaft is already installed, use a vernier caliper or digital micrometer for accuracy. When in doubt, consult your equipment's service manual or parts catalogue for the OEM seal part number, then match the dimensions.

"TC" denotes a double-lip seal with a garter spring. The primary (inner) lip faces the lubricant side and is held against the shaft by the spring to maintain a consistent sealing force. The secondary (outer) lip faces the atmosphere and acts as a dust excluder, preventing abrasive particles from reaching the primary lip and the bearing. A single-lip seal ("SC" type) omits the secondary lip and is typically used in cleaner environments or where space is limited.

NBR (nitrile butadiene rubber) is the most widely used seal material for petroleum-based lubricants — engine oil, gear oil, ATF, and hydraulic fluid. It performs reliably from approximately −40 °C to +120 °C (−40 °F to +248 °F). NBR is not recommended for use with brake fluid (DOT 3/4), phosphate-ester hydraulic fluids, or strong acids. If your application involves these fluids or sustained temperatures above 120 °C, consider a Viton (FKM) seal instead.

Clean the housing bore and shaft thoroughly before installation. Lightly lubricate the seal lip with the same oil or grease used in the application — never install a dry seal. Use a seal driver or a flat block of wood to press the seal squarely into the bore; never hammer directly on the seal face. Press until the outer face is flush with or just below the housing surface. Protect the lip from sharp shaft edges or keyways by wrapping the shaft with thin plastic film during installation, then sliding the film out once the seal is seated.

For reliable sealing, the shaft running surface should have a finish of Ra 0.2–0.8 µm (8–32 µin) and a hardness of at least 45 HRC in the contact zone. Surfaces that are too rough accelerate lip wear; surfaces that are too smooth can prevent the hydrodynamic oil film from forming. Avoid spiral machining marks, which can pump oil past the lip. If the shaft shows a wear groove from a previous seal, offset the new seal axially by 1–2 mm or use a repair sleeve.

TC oil seals are designed primarily for rotary shaft applications where the shaft rotates inside the stationary seal. They can also function in applications where the seal rotates with the housing while the shaft remains stationary ("reverse installation"), but lip wear rates may differ. They are not intended as static face seals or gaskets. For static sealing, an O-ring or gasket is the appropriate choice.

Common signs of a failed rotary shaft seal include visible oil weeping or dripping around the shaft exit point, oil staining on the housing or adjacent components, and lubricant contamination with dirt or water (indicating the dust lip has failed). A seal that has hardened, cracked, or lost its spring tension will no longer maintain adequate lip contact. Replacing the seal at the first sign of leakage prevents lubricant starvation in the bearing and avoids more extensive repairs.