Bearings sit at the heart of nearly every piece of moving machinery, quietly doing the job of reducing friction between rotating or sliding parts so that motion happens smoothly, efficiently and without premature wear. From small precision instruments to heavy agricultural machinery, the demands placed on a bearing vary enormously, and no single design can cope with every combination of load, speed and environment. That's why there are so many different types of bearings on the market, each built around a particular arrangement of rolling elements, contact angles and materials.
Choosing the right bearing isn't simply a matter of picking the cheapest option that fits the shaft diameter. Get it wrong and you risk premature failure or vibration. Get it right and you extend the working life of your machinery while keeping running costs down. This guide walks through the main types of bearings, explains how bearing housings protect and support them and answers some of the questions we're most often asked by customers specifying the correct bearing for their application.
Radial and axial loads: The starting point for any bearing choice
Before comparing individual bearing types, it helps to understand the two basic load directions a bearing might need to cope with. A radial load acts at right angles to the shaft, think of the weight pressing down on a wheel axle. An axial load, sometimes called a thrust load, acts along the length of the shaft, pushing or pulling in the direction the shaft is pointing.
Many applications involve a combination of radial and axial loads at the same time, particularly where a shaft changes direction, carries an angled component or experiences shock loading. Some bearing designs manage one load direction extremely well and the other not at all. Others are specifically engineered to share both loads simultaneously. Knowing roughly how much of each load type your application generates is one of the most useful pieces of information when narrowing down which bearing type will suit you.
Ball bearing types
Ball bearings use spherical rolling elements running in a track or race and are the most widely recognised bearing family thanks to their use in everything from skateboard wheels to electric motors.
Deep groove ball bearings
The standard, general-purpose option. A deep groove ball bearing is built primarily to carry radial loads, but the curvature of its groove also lets it absorb a moderate amount of axial load in either direction. Its simplicity, low cost and ability to run at high speed make it the default choice for countless everyday mechanisms.
Angular contact ball bearings
Where a deep groove design only tolerates a little axial load, an angular contact ball bearing is built to take it head on. The balls make contact with the races at a set angle, which lets the bearing handle a heavier axial load alongside its radial capacity. This makes them a popular choice for high-speed machine tool spindles and other precision equipment, where rigidity under combined loading really matters.
Self-aligning ball bearings
Real-world installations are rarely perfectly aligned. A self-aligning ball bearing solves this by allowing the inner ring, balls and cage to tilt a few degrees relative to the outer ring, automatically compensating for shaft deflection or housing misalignment, particularly useful where installation tolerances are looser or long shafts are prone to a little bending under load.
Double row ball bearings
By packing two rows of balls into a single, narrow unit, a double row ball bearing delivers significantly more load capacity than a single row design of the same width. This makes it a sensible choice where radial space is tight, but the load is too high for a standard deep groove bearing.
Double row angular contact ball bearings
Combining the benefits of the angular contact design with a second row of balls, this bearing type can accept thrust loads from both directions while still offering strong radial capacity and high rigidity. It turns up frequently in pumps, machine tool spindles and agricultural machinery, where shafts are subject to varying load directions during operation.
Roller bearing types
Where a ball bearing makes point contact with its race, a roller bearing's cylindrical, tapered or barrel-shaped rolling elements create a line of contact instead. That larger contact area spreads load over a wider surface, which is why roller bearings tend to outperform ball bearings when heavier radial or axial loads are involved. You'll typically find them in industrial gearboxes, railway axles and other demanding heavy-duty settings.
Cylindrical roller bearings
Built around straight cylindrical rollers, this type excels at carrying heavy radial loads while still permitting reasonably high-speed operation, found in gearboxes, compressors and general industrial machinery wherever a deep groove ball bearing wouldn't have the capacity.
Spherical roller bearings
A spherical roller bearing pairs heavy radial load capacity with a self-aligning outer ring, making it the roller equivalent of the self-aligning ball bearing. It can also absorb axial load in both directions, which is why it's a common sight in agricultural machinery, conveyor systems and other equipment exposed to shock loads and a degree of shaft misalignment during everyday use.
Tapered roller bearings
The tapered shape of the rollers and races allows this bearing to support substantial radial and axial loads at the same time. Tapered roller bearings are best known for their role in car and truck wheel hubs, but they also appear widely in agricultural machinery and other heavy vehicle applications where combined loading is the norm rather than the exception.
Thrust bearing types
Thrust bearings are built exclusively to manage axial load and aren't designed to carry any radial load at all, so, where there is also radial load, they must be used in conjunction with a separate radial bearing.
Thrust ball bearings
A thrust ball bearing arranges its balls between two flat washers, supporting pure axial load at low to moderate speeds. Thrust ball bearings are frequently paired with a radial ball bearing in the same assembly, so that each component only deals with the load direction it's best suited to.
Roller thrust bearings
When the axial load is too high for a thrust ball bearing to handle comfortably, a roller thrust bearing steps in. The larger contact area of its cylindrical or tapered rollers gives it substantially greater axial load capacity, making it the go-to option in heavier-duty machinery.
Needle bearing types
Needle bearings are a specialised branch of the roller bearing family, distinguished by rollers that are far longer than they are wide.
Needle roller bearings
By using very thin, needle-shaped rollers, this type packs a surprising amount of load capacity into a much smaller cross-section than a standard cylindrical roller bearing would need. That makes needle roller bearings the obvious choice wherever radial space is at a premium, which is exactly why they crop up so often in automotive transmissions, compact industrial assemblies and aerospace components.
Needle roller thrust bearings
Following the same logic, a needle roller thrust bearing delivers axial load support within an extremely tight axial footprint, making it useful in confined gearbox and machinery designs where every millimetre of space counts.
Plain bearings: an alternative to rolling element designs
Not every application calls for rolling elements at all. Plain bearings, sometimes known as bushings or sleeve bearings, rely on a sliding surface rather than balls or rollers to support the shaft. They're typically simpler and less expensive than rolling element bearings, and can be a sensible choice for lower-load, lower-speed applications, or where the bearing needs to be unusually compact, quiet or resistant to shock. The trade-off is generally higher friction and a shorter service life under demanding conditions, which is why most precision or high speed equipment still favours rolling element designs over plain bearings.
Bearing material guide
Once you've settled on a bearing type, material is the next decision - and it matters just as much. The right material protects against wear, corrosion or failure in whatever environment the bearing has to work in, while the wrong one can shorten its life dramatically, particularly in extreme conditions. To simplify that decision, we've put together a comprehensive bearing materials guide that covers the properties and applications of each option in detail. Here's a quick rundown.
SAE 52100 chrome steel is the standard choice where high hardness and wear resistance matter more than corrosion protection, making it well suited to general-purpose and high-load applications. Where some corrosion resistance is needed, 440 grade martensitic stainless steel (prefix "S") trades a little hardness for protection against moderate corrosive exposure, which is why it's a regular choice for food processing and medical devices. For the most demanding corrosive environments, AISI 316 austenitic stainless steel (prefix "S316") offers excellent corrosion resistance and is non-magnetic, though only suitable for low load, low speed applications such as those found in the marine, chemical and pharmaceutical industries.
Plastic bearings cover a wide range of properties depending on the polymer used. Acetal resin, or POM-C (prefix "AC"), combines low friction with good dimensional stability, making it a popular choice for low-load, low-precision applications in moisture-resistant environments. PEEK (prefix "PK") steps up considerably, offering higher strength, chemical resistance and high-temperature performance that suits aerospace, automotive and medical applications. Polyethylene (prefix "PE") prioritises impact resistance and low cost for light-duty uses such as packaging machinery, while PTFE (prefix "PT") is prized for excellent chemical resistance and low friction in chemical processing and food industry settings. PVDF (prefix "PV") rounds out the range, combining high purity with chemical resistance for semiconductor and pharmaceutical applications.
Ceramic bearings come into their own in the most extreme environments. Zirconia, or ZrO2 (prefix "CCZR"), offers high strength alongside non-magnetic properties, wear resistance and corrosion resistance, making it suitable for corrosive and extreme temperature conditions. Silicon nitride, or Si3N4 (prefix "CCSI") combines superior hardness with low density, thermal stability and non-magnetic behaviour for extreme temperatures, vacuum and aerospace use. Silicon carbide, or SiC (prefix "CCSC"), brings extreme hardness and chemical inertness to high-wear, chemical and very high temperature applications. Hybrid bearings (prefix "CB" or "SCB") round things off by combining metal races with ceramic balls, delivering higher speeds and improved performance for high-performance automotive and industrial machinery.
We've also put together a guide to various bearing applications, and a bike bearings guide and durable options for marine, chemical, pharmaceutical and automotive use, with detailed advice on which bearings to choose and why.
Choosing the right bearing material is just as important as selecting the bearing type itself - the wrong one can lead to premature wear, corrosion or failure, especially in extreme environments.
Installation and maintenance
Even the right bearing will underperform if it's installed incorrectly. Correct alignment, an appropriate fit between shaft, bearing and housing, and the right type and quantity of lubricant are all essential to getting the service life a bearing is designed to deliver. Incorrect shaft or housing fits can cause poor performance while misalignment increases vibration and accelerates wear.
Ongoing care matters as much as getting the installation right in the first place. Routine relubrication, periodic checks for noise or vibration, and prompt attention to any sign of contamination can add years to a bearing's working life. If a bearing isn't performing as expected, it's often worth checking the lubricant and fill level before assuming the bearing itself is at fault.
Choosing the right bearing for your application
With so many different types of bearing available, working out where to start can feel overwhelming. A useful approach is to consider, in order: how much radial load is involved, how much axial load is involved, how fast the bearing will rotate, how much space is available, whether misalignment is likely and what environmental conditions the bearing will face. Answering these narrows the field considerably, and from there material and housing design can be matched to suit.
Read more on the bearing selection process
Frequently asked questions
What's the main difference between ball bearings and roller bearings? Ball bearings make point contact with their races and tend to suit lighter loads and higher speeds, while roller bearings make line contact and generally handle heavier loads at the cost of higher friction and a lower tolerance for misalignment.
Can one bearing handle both radial and axial loads? Yes, angular contact ball bearings, tapered roller bearings and spherical roller bearings are all designed specifically to manage combined radial and axial loads, rather than just one or the other.
If you're still unsure which type of bearing or material best suits your application, the SMB Bearings team is happy to talk through the details with you. Call us on +44 (0) 1993 842 555 or email sales@smbbearings.com, and we'll help you find the right solution from our extensive range of small and miniature bearings.