What Are the Five Main Components of Ball Bearings?

As a key component in a vast array of machinery, a ball bearing offers a simple but effective way of facilitating frictionless motion between parts while adequately “bearing” a load. Though a plethora of ball bearing types exist, each of them tends to have five main components which define them: the retainer, races, lubricant, bearing balls, and shield. In this article, we will be discussing these central parts in detail so you may better understand how ball bearings function.

1. Retainer: The retainer is the part of a ball bearing that consists of the section between the inner and outer rings which hold the bearing balls within the mechanism. The retainer must hold the balls at an equal distance from each other and prevent them from touching to avoid excessive abrasion or wear. Moreover, it must also have an appropriate design with certain material strengths and balanced elasticity, in order to endure the load in the ball bearing for as long as possible. In general, there are three main retainer types, those of which are inner ring, outer ring, and ball controlled retainers. Whereas inner ring retainers are driven by the movement of the inner ring, the opposite is true of outer ring retainers, and ball controlled retainers are disconnected from both rings and are merely driven by the movement of the balls.

2. Races: Another central part of ball bearings are the inner and outer rings or races which provide a vital structure for each of the components contained within them. The races will typically have a uniform groove in the center so that as the balls roll, they will follow those grooves. With rings, the balls will remain confined in the device and won’t fall out or become stuck. Typically, the races will be made of steel, ceramic, or plastic, though other options exist.

3. Balls: As the name implies, all ball bearings have a set of balls that facilitate the smooth rotation between the rings. The number of balls within a ball bearing can consist of just a few or a number in the dozens depending on the size of the bearing. The central purpose of the balls is to transmit a load, and they are commonly made of acetal, stainless steel, glass, ceramic, nylon, and polypropylene.

4. Lubricant: Besides reducing friction and wear, lubricant can also aid with cooling, shock absorption, corrosion protection, and creating a more secure seal. Typically, bearing lubrication will consist of either greases, oils, or solid lubricants. Grease lubrication is recommended for general use at low to medium speeds and is one of the most frequently used types. Oil lubrication, on the other hand, is typically used if grease cannot be used due to technical or economic reasons. Lastly, solid lubricants may be used in special cases where liquid lubricant could pose a health or safety risk.

5. Shield: The shield is usually the last part to be mounted on the ball bearing and it is used to keep contaminants out of the bearing interior. It also keeps the lubricant in the bearing so it does not need to be replaced as frequently or affect surrounding machinery. Some shields make contact with the balls while others are non-contact to reduce friction and the risk of abrasion.


Ball bearings are useful components for lending smooth, frictionless motion to an assembly. Though there are many options to choose from, there are several defining parts that allow ball bearings to work effectively. As such it is important to source high-quality parts and properly maintain them, only making replacements as needed. For any present or future part requirements, Aerospace Store has you covered with a simple purchasing process that takes your operational needs in mind. Browse our vast inventory of over 2 billion parts which includes an entire catalog dedicated to aviation bearings. With representatives on standby, we promise rapid responses to your inquiries, and include a 24/7 Request for Quote (RFQ) service so that our customers can procure the parts they need with ease.


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