SKF bearings are some of the best in the world. They have a reputation for being extremely reliable and long-lasting. The company has been making bearings for over 100 years, so they have some experience with what makes a good bearing.

SKF bearings come in many different types, but most of them will contain an oil seal at the bottom of the shaft. This oil seal keeps contaminants from entering the inside of the bearing and causing damage.

The easiest way to tell if an SKF bearing is sealed is to look at its design. The seal is usually located at one end of the shaft, so simply look for it on that end of your bearing if you want to know if it's sealed or not.

Another way to tell if an SKF bearing is sealed is by looking at its packaging. If there's no mention of whether or not your bearing has an oil seal, then it probably doesn't have one (but this isn't always true).

A sealed SKF bearing will be marked with the letter ‘W’ and then a numeric digit to indicate the degree of protection.

The degree of protection is the amount of protection provided by a sealed bearing. It is not an indication of the quality, application or performance of the bearing. This information is provided to show how well the seal has performed in tests carried out by SKF.

The letter ‘W’ followed by a number indicates the degree of protection for water-immersed bearings. For example, W 100 means that the bearing has been tested under water at 100 kPa pressure for 24 hours without leakage and that it can be operated in a water environment up to this pressure.

A single letter indicates the degree of protection against dust or dirt (D). The letter ‘C’ followed by a number indicates that the seal has been tested under load with dust or dirt present in order to simulate operating conditions where this type of contamination may occur.

The most common seals are rubber sealed bearings, designated with a ‘2RS’ suffix.

These bearings have a raceway on both sides of the outer ring, and the seal is located between these raceways. The sealing lip is made from molded rubber, which compresses when the bearing is mounted in the housing and expands when the shaft is inserted into the bearing.

The 2RS seal has an internal lip that compresses against the outer ring to form a seal. It also has an external lip that presses against the inner race to compress it and form another seal. In this way, there are two independent seals inside each bearing.

The 2RS design provides a better seal than other configurations because it has more contact area and better compressive strength than standard seals found in other designs, such as 1RS or 3RS designs where only one lip contacts each shoulder of the bearing assembly at any given time during operation.

If a bearing has a metal shield and a rubber seal, this designation is reversed such as 'Z' and '2RS'.

Many bearings have an 'RS' suffix, meaning they have a rubber seal. This is the most common type of seal used on bearings.

If a bearing has a metal shield and a rubber seal, this designation is reversed such as 'Z' and '2RS'. The metal shield is called an inner ring, which is pressed onto the shaft and provides additional support for the outer ring.

The '2RS' designation denotes an inner ring with two rubber seals that provide additional protection from dust or other contaminants getting into the bearing race.

If the bearing has only one seal, it is usually indicated by the suffix ‘2RS1’ or by the addition of a trailing dash (-).

The suffix ‘2RS1’ is used for sealed bearings that have a second internal ring groove machined into the inner ring raceway. This allows for an increased amount of lubricant to be retained within the bearing, which increases the life of the bearing by reducing wear and increasing heat dissipation.

If there are two seals, then it is indicated by adding a trailing dash (-).

In general, most modern bearings have two seals, with one seal inside the inner ring raceway and one on the outer ring raceway.

The seal on the outer ring raceway ensures that no contaminants enter from outside of the engine or transmission during operation; this helps prevent corrosion from forming on any exposed metal surfaces in contact with each other. The seal on the inner ring raceway prevents external contaminants from entering through any openings between outer rings and inner rings (such as when changing gears), which can lead to excessive wear and failure of both components over time if not addressed properly.

Many bearings have seals with different materials on each side of the bearing; this is designated ‘RZ’ followed by the material designation.

The RZ designation has been used for many years to indicate that one side of the bearing has a rolling element (ball or roller) and the other side has a cage (or sometimes balls).

The meaning of ‘RZ’ is often misunderstood. Many people believe that it means that both sides have rolling elements; but this is not correct. It only means that there are two different materials used on each side of the bearing.

The most common application for RZ bearings is when a non-contact seal is required on both sides of the bearing. For example, in some applications where there is high pressure and temperature, it may be necessary to use an oil film to protect against leakage from one side of the bearing while also providing lubrication from another side. This would require an RZ bearing with seals on both sides.

An understanding of how SKF bearings are marked can help you to determine if they are sealed or not.

The nomenclature on SKF bearings can be too confusing to understand. There are many different systems in use, and it is not always easy to determine which system applies to a particular bearing. The most commonly used systems are:

SKF Bearing Identification System (BIS)

SKF Bearing Marking System (BMS)

SKF Standard Marking System

A knowledge of these marking systems helps you to determine if a bearing is sealed or not.

Finally, to know if a bearing is sealed, the easiest way to tell is by the markings on the outer diameter of the bearing. If both bearings are the same they should have a "Z" suffix in their model number if they are sealed. If they have no suffix it means that they are not.