Oil seals are widely used as sealing devices for machines.

JTEKT's oil seals are described in our catalog, Oil Seals & O-Rings.
However, the catalog uses a large number of technical terms and is very long, so many people seem to have trouble handling it.

Therefore, this series of columns will summarize the following in order:
• The structure, functions, and types of oil seals
• How to select the right oil seal
• Handling of seals, and causes and countermeasures for oil seal failure

1. What are oil seals?

A wide range of sealing devices are used in various machines.
Sealing devices serve the following functions:

• Prevent leakage of sealed lubricant from inside
• Prevent entry of dust and foreign matter (dirt, water, metal powder, etc.) from outside

As shown in Figure 1, sealing devices come in two types: contact and non-contact.
Oil seals are among the major contact type sealing devices.

Figure 1: Types of sealing devices

Please see the following for the types of sealing devices for bearings.
How to Select the Right Bearing (Part 7): Components surrounding the bearing

2. Oil seal structure and functions

Oil seals come in various shapes to fit the machines and substances to be sealed.
Figure 2 shows the structure and the names of the various components of the most typical oil seal.
The functions of the various components are also indicated in Table 1.

Figure 2: Typically shaped oil seal and component nomenclature

* "KOYO" is a registered trademark of JTEKT.

Table 1: The functions of the various components

No.

Name

Functions

①

Its sealing edge comes in full contact with the shaft surface in order to provide excellent sealing performance.
(See Figure 3.)

②

③

④

⑤

⑥

⑦

⑧

Figure 3: Sealing function of main lip radial load
* "KOYO" is a registered trademark of JTEKT.

Figure 4 shows the features of a JTEKT oil seal.

Figure 4: JTEKT oil seal features

For more detailed information, please see the following:

Names and functions of seal components　

3. Seal types and numbering system

1) Common seal types and their features

Seals are classified by O.D. wall material, lip type, and whether they have a spring or not.
Major oil seals are specified in ISO 6194-1 and JIS B 2402-1.
Table 2 shows the common types of oil seals, while Table 3 shows the features of each type of oil seal.
Table 4 lists the JTEKT oil seal type codes and corresponding ISO and JIS standards.

Table 2 a): Common types of oil seals (with spring)

Metal O.D. wall
(with a reinforcing inner metal case)

Without minor lip


Type code

With minor lip


Type code

Table 2 b): Common types of oil seals (without spring)

Without minor lip

Type code

With minor lip


Type code

Table 3: Features of each seal type

No.

Type

Features

1

2

3

4

5

Table 4: JTEKT oil seal type codes and corresponding ISO and JIS standards

ISO 6194-1 1)

Notes
1) ISO: International Organization for Standardization
2) 2) JIS: Japanese Industrial Standard

2) Special seal types and their features

JTEKT provides special seals for use in a wide variety of machines and applications.
Table 5 lists the major special seals, their shapes, and their features.

Table 5: The major special seals, their shapes, and their features

Helix Seal

Super Helix Seal

　　　　　　　　　　　　a)

Function of hydrodynamic ribs

For more detailed information, please see the following:

Special seal types and their features

3) Seal numbering system

Figure 5 explains the JTEKT seal numbering system.
Seal numbers consist of
　(1) the seal type code,
　(2) the spring code,
　(3) the lip type code,
　(4) the dimensional numbers, and
　(5) the special type code,
and Table 6 shows examples of each of these codes/numbers.

Figure 5: JTEKT seal numbering system



Table 6: Codes and numbers used in seal numbers

MH: O.D. wall is a rubber material
HM: O.D. wall is a metal case
MH(S)H: O.D. wall is metal with a reinforced inner metal case

No code: without minor lip

A: with minor lip

No code: without minor lip

A: with minor lip

J: Additional code is added here as an identifier when two or more seals have exactly the same type codes and dimensional numbers.

Note: For seal type codes, see Table 2.

4. Example of the applications of seals

Oil seals are used in a great many machines.

1) Oil seals for cars

Oil seals are used in many areas around the car.
Figure 6 shows the places where each seal type is used.

Figure 6: Oil seals for cars

For more detailed information, please see the following:

Oil seals for cars

2) Oil seals for steel production equipment

Oil seals are used in a great many devices for steel production equipment.
Figure 7 shows the places where each seal type is used in a rolling mill.

Figure 7: Oil seals for steel production equipment (rolling mill)

For more detailed information, please see the following:

Oil seals for steel production equipment

5. Conclusion

Oil seals are one of the major contact type sealing devices.
• They prevent leakage of the lubricant or other sealed substance, and
• prevent entry of dust and foreign matter (dirt, water, metal powder, etc.) from outside.

Oil seals come in various shapes to fit the machine or substance for sealing.
For this reason, when designing a machine, it is important to select the oil seal that is right for that machine.
Next time, we will explain the key points to consider when selecting your oil seal.

If you have any technical questions regarding oil seals, or opinions/thoughts on these "Bearing Trivia" pages, please feel free to contact us using the following form:

Lubrication of O-rings is essential for the proper function and full-service life of the seal, but also to ensure the machine, motor, engine, or device in which it is placed does not malfunction from a blown seal. A grease or oil application at assembly helps to protect the O-ring from damage during use. An additional benefit is the protection a lubricant provides for the part, from general water resistance and minimization of frictional forces to preventing atmospheric degradation by elements such as ozone. Lubricated O-rings reduce asperities of metal edges that may leak vacuum applications and seal pneumatic applications requiring dynamic service.

Knowing how to lubricate an O-ring, which lubricant is best, and when to apply it will provide stability, maintain consistency, and optimize the service life of your O-ring. Let’s take a closer look:

How to Lubricate O-Rings

Providing a thin, uniform coating of lubricant on the surface of O-rings before installation increases the part’s functionality, eases installation, and extends its service life. The application of a thin film of lubricant covering the O-ring will fill in any gaps or spaces where the O-ring joins the mated part or parts. Properly applied, lubrication prevents drying out, reduces tension between surfaces, and fits the part more snugly into place.

Though there are several methods of applying lubricant to an O-ring, the three more common ways are:

• Apply the lubricant directly to the O-ring using a brush or your fingers; spread or brush evenly.

• Dip the O-ring into a container of lubricant.

• Dispense the lubricant directly into the O-ring packaging and spread evenly within.

Which Lubricants Are Best for the Application?

Numerous types of lubricants can be used to install O-rings. Among the more common choices are petroleum distillates, solvents, soap and water, polymers, and ester-based grease products. Unfortunately, many of these traditional choices also have caused health and safety concerns combined with damage to the rubber O-ring.

Petroleum-based products can cause elastomeric rubber to swell or dry out. Solvents are not ideal lubricants and contain high Volatile Organic Compounds (VOCs) that may be flammable or pose very real health risks. Soap and water solutions are safer solutions than solvents and petroleum-based lubricants but are nominal, inconsistent, and reactivated in damp environments after assembly.

As most O-rings and seals are made of synthetic elastomeric polymers, i.e., “rubber” material such as nitrile, EPDM, and Neoprene, they are the best lubricants for them derived from synthetic compounds. At the top of the list are silicone-based and ester-based lubricants. In comparison to other types of lubricants, synthetic-based lubricants perform better over a wide range of conditions. They offer an excellent reduction in friction, are waterproof, and have low volatility, high-temperature stability, and low-temperature fluidity. Where ester-based lubricants are biodegradable, both are safe, and neither pose health risks or contamination by contact when you use your hands or fingers for application. These lubricants can be used on natural rubber products as well.

When to Apply or Reapply Lubricants to O-Rings

The first step to ensure a long life for an O-ring application is at the time of installation. Look to any manual or set of directions, and it is highly recommended to lubricate most seals before installing or changing them properly. Proper lubricants help protect O-rings from damage due to abrasion, pinching, or cutting, all of which could lead to premature product failure. The issues that arise with poor or underperforming O-rings—tearing, overstretching, and improper seating—usually occur during installation. Lubricating the part will help prevent these problems. Applying a thin, uniform film of lubricant will help seat the O-ring correctly and fit tightly.

Take the time to wipe clean and reapply a fresh coat of lubrication on O-ring parts during routine maintenance or when making repairs of mechanical equipment, devices, engines, machinery, and so forth that house O-rings.

O-rings are in many ways an indispensable component found in countless applications. They play an essential role in the manufacture and operation of vehicles, machinery, appliances, plumbing, pumps, motors, medical devices, and much more. For O-rings to function correctly, care must be given during installation. Surfaces should be wiped clean and free of foreign material or substances and then lubricated to increase functionality, extend the service life, and provide extra protection for the part or component. In short, knowing how to lubricate an O-ring, when to apply it, and selecting the best lubricant for the application will ensure a long service life for the part.

How long does tractor oil seal last?

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The lifespan of a tractor oil seal can vary depending on several factors, including the quality of the seal, the operating conditions of the tractor, and how well the seal is maintained. Generally, a tractor oil seal is designed to last for several thousand hours of operation under normal conditions. However, there are several factors that can affect its longevity.

Factors Affecting Tractor Oil Seal Lifespan

Quality of the Seal:

The quality of the PTFE oil seal itself plays a significant role in determining its lifespan. High-quality seals made from durable materials such as rubber or silicone are more likely to last longer than lower-quality seals.

Operating Conditions:

The operating conditions of the tractor, such as temperature, pressure, and the presence of contaminants, can impact the lifespan of the oil seal. Tractors operating in harsh environments or subjected to extreme temperatures may experience accelerated wear and tear on the seals.

Maintenance:

Regular maintenance and inspection of the oil seal are essential for prolonging its lifespan. Proper lubrication and ensuring that the seal is free from dirt, debris, and other contaminants can help prevent premature wear and leakage.

Seal Installation:

The correct installation of the oil seal is crucial for optimal performance and longevity. Improper installation, such as incorrect alignment or excessive seal compression, can lead to premature failure.

Signs of Oil Seal Failure

Oil Leaks:

One of the most common signs of OEM oil seal failure is the presence of oil leaks around the seal area. If you notice oil pooling or dripping from the seal, it may indicate that the seal is damaged or worn out.

Increased Oil Consumption:

A sudden increase in oil consumption without any noticeable leaks could be a sign that the oil seal is failing. As the seal deteriorates, it may allow oil to bypass and enter the engine or transmission, leading to higher oil consumption.

Loss of Lubrication:

If the oil seal fails, it can result in a loss of lubrication to critical engine or transmission components. This can cause excessive friction and wear, leading to further damage if not addressed promptly.

Conclusion

In conclusion, the lifespan of a tractor oil seal can vary depending on factors such as seal quality, operating conditions, maintenance, and installation. While a well-maintained and properly installed oil seal can last for several thousand hours of operation, it’s essential to monitor for signs of wear and failure and address any issues promptly to prevent damage to the tractor’s engine or transmission. Regular inspection and maintenance are key to maximizing the lifespan of tractor oil seals and ensuring reliable performance.