Oil Seal TCN - Pressure

Oil Seal Type TCN | Pressure-Loadable Rotary Shaft Seal

The TCN oil seal is a specially designed rotary shaft seal capable of handling pressurized applications. Unlike standard shaft seals, the TCN features a pressure-loadable sealing lip, which ensures reliable performance even under elevated system pressures. Its elastomer-coated outer diameter and short spring-loaded sealing lip guarantee secure sealing within the housing, while the additional protective lip offers effective defense against external contamination such as dust, dirt, and moisture. This double function—internal pressure resistance and external contamination protection—makes the TCN oil seal particularly suitable for pumps, hydraulic motors, and other pressurized units. With its robust construction and modern sealing design, the TCN provides long-lasting reliability in demanding environments.

Features of the TCN Oil Seal

The TCN oil seal is specifically engineered to deliver reliable performance in pressurized applications, making it a trusted choice for demanding industries. Its pressure-loadable sealing lip design ensures tight and secure sealing even when exposed to elevated system pressures, while its elastomer-coated OD provides reliable static sealing inside the housing. The integrated protective lip serves as a barrier against dust, dirt, and other contaminants, helping extend the lifetime of machinery. Thanks to its flexibility, the TCN performs well in housings with high thermal expansion, such as light metal designs, and remains effective in split housings or surfaces with increased roughness. By preventing fretting corrosion, it safeguards components from long-term damage. Additionally, it is suitable for sealing thin-body fluids and gaseous media, further enhancing its versatility.

Applications of TCN Shaft Seals

The TCN shaft seal is designed for use in rotating and pressurized applications where conventional rotary seals are not sufficient. Its reinforced lip design makes it ideal for pressurized units such as pumps and hydraulic motors, where consistent sealing under pressure is critical for safety and efficiency. By combining pressure resistance with contamination protection, the TCN ensures reliable operation in demanding environments, from industrial machinery to fluid power systems. In less demanding, non-pressurized applications, customers may prefer the SC oil seal, which provides dependable dynamic sealing. For general use with double lip protection, the TC oil seal is a suitable alternative. Together, these types form a complete sealing solution range for different operational requirements.

Materials and Variants

The TCN oil seal is available in a variety of material combinations to ensure optimal performance in different applications. The standard version is made from NBR 80 blue elastomer, which provides excellent durability and compatibility with mineral oil-based lubricants. For more demanding conditions, optional elastomers such as FKM, Silicone, ACM, HNBR, CR, and EPDM can be selected, offering enhanced resistance to temperature, chemicals, or specific media. The spring is manufactured from either spring steel (DIN EN 10270-1) or stainless steel 1.4301, ensuring reliable force on the sealing lip. The metal case is produced from carbon steel (DIN EN 10139) or stainless steel 1.4301, depending on the application requirements. For high-temperature environments, the TCN Plus - Viton series oil seals with FKM material provide an excellent alternative.

Alternative Names for the TCN Oil Seal

The TCN oil seal, also known as the Taiwanese designation for the OS-N21 type, is recognized under various codes and trade names across different manufacturers and suppliers. It is referred to as Dichtomatik WASY, Anyseals OS-N11, and B+S TR-U, while some brands like Chicago R and Elring market it under their own standards. Other equivalents include Eriks RST-D, FP Paris GAP, FST BAB SL, and Gaco. In addition, it is identified as Goetze 827 SK, Kaco DGSP, Kramp BABSL, and in some markets simply under National or Paulstra. Further designations include Pioneer W, Rolf, and Stefa CF. Internationally, the seal is widely recognized as Taiwan / NOK TCV or TCN, while also known as Vota BAB SL, Ebele, and Kimman KAS-P. These variations ensure easy cross-referencing and compatibility across different industries.

Operating Parameters of TCN Oil Seals

The TCN oil seal is engineered to withstand demanding operating conditions where pressure resistance and durability are essential. It is suitable for use within a temperature range of -30°C to +100°C, although the maximum recommended operating temperature is 80°C when synthetic lubricants are applied, in order to ensure long service life. Thanks to its special lip design, the TCN is pressure-loadable, with exact limits available in the corresponding sealing charts. Shaft speeds should also follow the guidelines set out in the standard rotary shaft seal operating charts, ensuring safe and reliable performance. In terms of media compatibility, the seal is designed for mineral oil-based lubricants as well as many synthetic lubricants, though testing is advised when using synthetic options with no proven track record in the application.

Design Information

To achieve maximum performance, the TCN oil seal must be installed under specific design conditions for both the shaft and the housing.

Shaft Requirements

The shaft should comply with ISO h11 tolerance and have a hardness of at least 45 HRC to resist wear. The surface finish must remain within Ra 0.2 – 0.8 μm, Rz 1 – 5 μm, and Rmax ≤ 6.3 μm, with a lead-free finish to prevent leakage and ensure consistent sealing over time.

Housing Bore Requirements

The housing bore must follow ISO H8 tolerance and feature a roughness of Ra 1.6 – 6.3 μm, Rz 10 – 20 μm, and Rmax ≤ 25 μm, providing secure fit and reliable static sealing.

Installation Guidelines

Correct installation is essential to guarantee durability and efficiency. For best results, please follow our installation guide for oil seals.

Related Oil Seals

Alongside the TCN oil seal, we offer several related products to suit different sealing requirements. For general applications, the TC oil seal provides a double lip design with dust protection, while the SC oil seal is a reliable choice for standard rotary shaft sealing without pressure load. For high-temperature environments, the TCN Plus - Viton series oil seals made from FKM material deliver superior heat resistance. To explore all available types and material options, view our complete selection of general rotary shaft seals.

Sealing principle: How does a TCN work?

The pressure resistance of a TCN oil seal does not rely on additional components, but on the geometry of the sealing lip. This design is commonly referred to as a pressure-loadable sealing lip, indicating that the lip geometry is specifically intended to remain stable under internal system pressure. The short primary lip, supported by a garter spring, is designed to remain axially and radially stable as internal pressure increases and is less prone to overturning than the longer lip of a standard TC oil seal. As a result, the contact line between the lip and the shaft remains controlled and reproducible, preventing leakage without unnecessarily increasing the sealing force.

The spring provides a constant base load on the lip, independent of minor wear or dimensional tolerances, while the short lip length limits the influence of pressure and temperature on lip deformation. This makes the TCN suitable for sealing both viscous and low-viscosity media, and in specific cases even gaseous media, provided that rotational speed and heat generation remain within permissible limits.

The secondary dust lip has no pressure-sealing function but serves a protective role by keeping external contaminants away from the sealing zone. This reduces abrasive wear of the primary lip and contributes to stable sealing performance over the long term. The fully elastomer-coated outer diameter, executed with a smooth surface, simultaneously ensures reliable static sealing in the housing. This outer diameter also prevents fretting corrosion between the seal and the housing, which is especially relevant in aluminium and split housings. This allows the seal to perform reliably in housings with thermal expansion, increased surface roughness or split constructions, without the risk of fretting corrosion or micro-leakage along the outer diameter.

Functional application: Where to use a TCN oil seal?

TCN oil seals are used in rotating systems with internal pressure, such as hydraulic pumps, hydraulic motors and other pressure-loaded units. Typical examples include gear pumps, vane pumps and orbit motors, where the shaft seal is directly exposed to system pressure and where a standard TC oil seal does not provide sufficient sealing reliability. TCN seals are also commonly used in compact hydraulic units, power packs and mobile machinery, as they provide pressure-resistant sealing without requiring additional installation space.

In addition, TCN oil seals are applied in industrial drives and transmissions in which local pressure build-up may occur, for example due to limited venting or temperature increase. In such situations, the stable lip design prevents oil or low-viscosity lubricants from being forced out along the shaft. The combination of pressure resistance, double-lip sealing and an elastomer-coated outer diameter also makes the TCN suitable for aluminium or split housings, such as those commonly found in refurbished pumps and motors.

At the same time, the TCN is not a universal solution. At high rotational speeds, the permissible pressure decreases rapidly, making this type unsuitable for fast-running shafts or applications in which pressure and speed are simultaneously high, such as high-speed spindles or turbomachinery. In those cases, other sealing concepts, such as cassette seals or mechanical seals, are required to ensure reliable sealing.

Material selection: matching the medium and temperature

Although the construction of a TCN oil seal is fixed, the elastomer material largely determines its suitability for a given application. For the standard NBR material combination, the typical operating temperature range is −30 °C to +100 °C, with a recommended maximum of 80 °C when synthetic lubricants are used to ensure long service life. NBR is the standard material and is suitable for mineral oils and general hydraulic applications. It offers good wear resistance but has a limited temperature range.

FKM is selected when temperature or chemical exposure is higher. This material remains stable at elevated temperatures and in more aggressive media but comes at a higher cost.

HNBR represents an intermediate solution with improved mechanical properties compared to NBR.

Other elastomers such as ACM, EPDM, CR or silicone are only used when specific media or temperature requirements make them necessary. When synthetic lubricants are used for which no field experience is available, compatibility should be verified through testing, preferably under practical operating conditions.

The spring and reinforcing ring can also be supplied in stainless steel when corrosion resistance is required.

Material Table

Comparable oil seals

In practice, a TCN oil seal is often compared to a standard TC oil seal, as their basic construction is similar. The difference lies in the intended application: a TC seal is designed for sealing without relevant internal pressure, whereas a TCN is explicitly intended for pressure-loaded conditions.

Compared to metal outer diameter oil seals, the TCN is more tolerant of housing variations and thermal expansion. Compared to cassette seals or mechanical seals, it is simpler, more compact and more cost-effective, but also more limited in terms of pressure and speed capability. The TCN therefore occupies a clearly defined niche within the spectrum of rotary shaft sealing solutions.

Selecting the right TCN: dimensions, tolerances and operating conditions

When replacing or specifying a TCN oil seal, different manufacturers may use alternative designations for the same pressure-loadable seal design, as shown in the cross-reference table below.