Oil Seal 18mm-19mm-20mm ID Rotary Shaft Double Lip R23 TC TTO All Depths NBR

Measure three dimensions on your existing seal or housing: the inner diameter (shaft OD), the outer diameter (housing bore ID), and the depth (width). These correspond to the "Inner Ø x Outer Ø x Depth" option format used in this listing. For example, a seal marked 20 x 40 x 7 has a 20mm shaft bore, 40mm housing bore, and 7mm width. Always verify all three dimensions before ordering.

TC stands for a double-lipped seal design. The primary lip (inner) faces the oil side and retains lubricant; the secondary lip (outer) faces the atmosphere and acts as a dust and dirt excluder. This dual-lip configuration makes TC seals suitable for applications where both oil retention and contamination exclusion are required, such as gearboxes, differentials, and axle housings.

NBR (nitrile butadiene rubber) performs well with petroleum-based lubricants including engine oil, gear oil, ATF, and hydraulic fluid. It is rated for temperatures from approximately –40°C to +120°C. NBR is not recommended for use with brake fluid (DOT 3/4), phosphate ester hydraulic fluids, or steam. If your application involves these media, a FKM (Viton) seal would be more appropriate.

These are different naming conventions used by various standards bodies and manufacturers for the same basic double-lip rotary shaft seal with a metal case and garter spring. TC is the ISO/metric designation, R23 is a common DIN/European reference, and TTO is used in some aftermarket catalogs. All three refer to the same seal construction and are interchangeable when dimensions match.

Clean the housing bore and shaft thoroughly before installation. Lightly lubricate the seal lips and the outer case with the same oil the seal will be retaining. Press the seal squarely into the housing bore using a seal driver or a flat block of the correct diameter — never strike the seal directly with a hammer. Press until the outer face is flush with or slightly below the housing face. Avoid cocking the seal during installation, as this can damage the lip and cause immediate leakage.

TC NBR oil seals are suitable for moderate to high shaft surface speeds, typically up to approximately 4–8 m/s depending on the specific size and shaft finish. For very high-speed applications, shaft surface finish (Ra 0.2–0.8 µm recommended) and shaft hardness (HRC 45–60 recommended) are critical factors. If your shaft speed exceeds these ranges, consult the seal manufacturer's speed rating for the specific size selected.

All dimensions in this listing are metric (mm). If your shaft is imperial, convert the shaft diameter to millimeters (1 inch = 25.4mm) and match to the nearest available inner diameter. For example, a 3/4" shaft is 19.05mm, which would typically use a 19mm ID seal. Always verify the outer diameter and depth also match your housing before ordering.