How to Read Oil Seal Types: Understanding TC, TG, TB and EC Structures

Number of hits：202026-10-05 11:25:07　

Oil seal model codes such as TC, TG, TB, and EC are commonly seen in industrial sealing catalogs. However, these designations should not be interpreted as a universal code in which every letter always has exactly the same meaning across all manufacturers.

The safest way to identify an oil seal is to consider its complete structure, dimensions, material, and application rather than relying on the model letters alone.

TC Oil Seal: A Common Double-Lip Structure

A TC oil seal is commonly associated with a double-lip radial shaft seal. The primary sealing lip retains oil or lubricant, while the outer dust lip helps prevent dust, dirt, and other contaminants from reaching the shaft sealing area.

A spring-loaded sealing lip is commonly used to maintain radial contact with the rotating shaft. Depending on the product design, the metal case may also be covered or partially covered by elastomer.

TC-type seals are widely used in motors, gearboxes, pumps, machinery, and other rotating equipment.

TG-Type Designs: Pay Attention to the Specific Construction

TG designations can refer to oil seals with an external-threaded outer surface. The thread-like structure on the outside of the seal can help improve the seal's fit and sealing characteristics in the housing.

However, TG is not a sufficient description of every structural detail. A specific model should be checked against the manufacturer's technical drawing.

For example, a TG4 oil seal has a particular three-lip external-threaded skeleton construction. It includes a main sealing lip, an auxiliary lip, and a dust lip. The main sealing lip is spring-loaded, while the auxiliary lip is not spring-loaded but contacts the shaft. This specific structure should not be confused with a conventional two-lip TC oil seal.

TB Oil Seal: Confirm the Manufacturer's Definition

TB is another designation frequently found in oil seal catalogs. Its exact construction can vary depending on the manufacturer's product series or classification system.

For this reason, buyers should check the manufacturer's drawing or specification rather than assuming that every TB seal has an identical structure.

Important information may include the metal case arrangement, elastomer coverage, number and type of sealing lips, spring configuration, dimensions, and material.

EC: A Different Type of Sealing Construction

EC is commonly used in certain end-cover or end-cap sealing designs rather than simply representing another version of a standard radial shaft seal.

Because the structural details of EC seals can vary between product ranges, the application and technical drawing are particularly important when selecting a replacement.

The housing geometry, shaft arrangement, sealing direction, and installation method should all be checked before ordering.

Model Code Is Only the Starting Point

When identifying an oil seal, the model code is useful, but it should not be the only information used.

The shaft diameter, housing bore, seal width, lip configuration, material, spring arrangement, operating temperature, rotational speed, pressure, and sealing medium can all affect whether a particular seal is suitable.

For purchasing or replacement work, comparing the complete specification with the original seal or equipment drawing is much safer than selecting a product based only on a familiar model code.

In sealing applications, the structure behind the code matters more than the letters themselves.