Types of Bearings: How to Choose the Right Bearing for Your Application.

The many types of bearings on the market all solve the same basic problem: a shaft has to turn, a carriage has to slide, or a pivot has to swing, yet selecting between them depends entirely on your engineering application. Something has to carry the load while allowing that motion with as little resistance as possible. The families of bearings that do this job are not interchangeable. They differ in the directions of load they accept, the speeds they tolerate, the space they can occupy and the environmental conditions they survive.

This guide demonstrates bearing selection, leading with the engineering decisions involved, then introduces each bearing family as the answer to a particular version of it: a route from your application to a shortlist of potential solutions.

Contents: 

• How Bearings Work

• Types of Bearing Load: Radial, Axial or Combined

• Ball Bearings and Roller Bearings: What Actually Differs

• The Most Common Types of Ball Bearings

• Thrust Bearings for Axial Loads

• Needle Roller Bearings for Tight Radial Envelopes

• Plain Bearings and Slide Bearings

• Linear Bearings for Straight Line Motion

• Bearing Inner Rings and Shaft Mounting

• Types of Bearings Chart: Load, Speed and Environment Compared

• Material Selection When Specifying Bearings

• A Bearing Selection Checklist

 

How Bearings Work

Every bearing exists to constrain a moving element in some directions while leaving it free in others, doing so with as little friction as the application and tolerances can afford. Only two mechanical strategies provide these properties. 

The first is sliding contact. Two surfaces bear directly against one another, with materials chosen or treated to slide cleanly without grabbing or causing undue friction. This is the principle behind plain bearings.

The second is rolling contact. Hardened rollers or balls, also known as ‘rolling elements', are held between an inner and an outer raceway, so the relative motion becomes rolling rather than dragging. Because a rolling element makes only a small contact point with each raceway, resistance to motion falls sharply compared with two surfaces sliding across one another. That is the idea behind the rolling-element families: ball bearings, roller bearings and their derivatives.

Every bearing type is a variation on those two strategies, shaped by the direction of the load and by the space available to carry it; knowing which to select depends on a number of critical factors at the design stage.

 

Types of Bearing Load: Radial, Axial or Combined

The crucial first step in bearing selection is determining the direction of the forces acting upon the assembly your bearing will be housed in.

• Radial Loads act perpendicular to the axis of rotation. A pulley tensioned by a belt, a load-bearing wheel or a driven gear all impose radial forces. Radial bearings feature raceway geometry specifically designed to support these perpendicular loads while efficiently transferring the desired rotation.

• Axial (Thrust) Loads act parallel to the axis of rotation. A vertical spindle supporting a mass, a lead screw pushing a carriage or a rotary table pressing onto its base all generate axial forces. The raceway geometry required to support thrust loads differs significantly from radial designs.

• Combined Loads occur in most real-world applications. Establishing the ratio of radial to axial force is the fastest way to narrow down your bearing options. Predominantly radial or axial forces dictate specific bearing families, whereas genuinely mixed loads require either a specialised combined-load bearing (such as a tapered roller bearing) or a two-bearing arrangement where each handles a dedicated force vector.
  
  

Once your project's primary load profile is established, two further operating constraints finalise the specification:

• Rotational Speed: Rolling-element bearings are engineered for continuous, high-speed rotation with minimal friction, whereas sliding surfaces (plain bearings) are often better suited for slow oscillation or extremely high static loads.

• Spatial Envelope: The available radial and axial room within your housing frequently dictates the final choice. Tight spatial constraints often rule out standard bearings, necessitating specialised solutions like thin-section or needle roller bearings.

Ball Bearings and Roller Bearings: What Actually Differs

There are two standard families of rolling elements featured within roller bearings: ball and cylindrical. The geometry of the rolling element dictates the fundamental performance characteristics of the bearing, primarily governing the trade-offs between load capacity, maximum speed and system rigidity.

Ball bearings utilise spherical elements that contact the raceways at a single point, which deforms slightly into an ellipse under operating loads. This minimal contact area significantly reduces rolling friction, making ball bearings the standard choice for continuous, high-speed rotation. Their point-contact geometry also inherently tolerates minor shaft deflections or housing misalignment without catastrophic failure. However, because the force is concentrated into a highly localised area, overall load capacity and system rigidity are fundamentally lower than those of a comparably sized cylindrical roller bearing.

Roller bearings, whether cylindrical, tapered, or needle variants, contact the raceways along a continuous line down the roller face. Spreading the load across a broader footprint drastically increases the bearing's capacity and stiffness within the same spatial envelope as a ball bearing, making them the strict preference when handling heavy loads is critical. This expanded surface area comes at the cost of higher friction and heat generation, which typically restricts maximum operating speeds when compared to ball variants. Additionally, it's worth keeping in mind that standard line contact makes roller bearings highly sensitive to angular misalignment, which can cause severe edge-loading stresses if the shaft and housing are not precisely aligned.

The Most Common Types of Ball Bearings

Ball bearings are the largest of the rolling-element families when looking at the number of options available and cover the widest range of potential application types. Variations of ball bearings mostly cover mounting options, section height and load capacity.

 

Deep Groove Ball Bearings

The deep groove ball bearing is the default rolling-element bearing and the right starting point for most rotating shafts. Its raceways are cut as deep grooves whose arcs closely match the ball diameter, which allows it to carry a radial load as its main duty plus a moderate axial load in either direction. It runs well at speed, needs no special mounting arrangement and suits the great majority of general rotary applications.

If you have a rotating shaft, a mainly radial load and no unusual constraint, start with deep groove ball bearings and only move on if something rules them out.

Shop Deep Groove Ball Bearings.

 

 

 

Flanged Ball Bearings

A flanged ball bearing is a deep groove bearing with an integral flange on the outer ring. The flange locates the bearing axially against the face of the housing, so the bore does not have to be machined with a shoulder or fitted with a retaining ring to set its depth. 

This is a mounting solution rather than a load solution. Choose flanged ball bearings where a through-hole is easier to produce than a stepped bore, or where positive axial location matters in a thin housing wall. Where a plain bore is retained instead, snap rings for shafts do the equivalent job from the shaft side.

Shop Flanged Ball Bearings.

 

Thin Section Ball Bearings

A thin section ball bearing has an unusually small cross-section for its bore diameter, meaning the rings are slim in both radial and axial terms. The main benefit is form factor: a larger shaft can be accommodated without the large outside diameter that a standard section would demand.

That makes thin section ball bearings the family to reach for on rotary joints, gimbals, robotics and instrument work where a shaft or housing has to pass through the bearing and there is no space to spare around it. The compromise is axial load: a slim section carries less than a full section of the same bore, meaning the non-raceway load support is reduced.

Shop Thin Section Ball Bearings. 

 

 

Double Row Ball Bearings

Adding a second row of elements to the same bearing raises the load the unit can carry and improves its resistance to axial loads, because the two rows are separated along the raceway axis. A double row ball bearing therefore suits applications where a single row would be marginal on capacity, or where the shaft is loaded in a way that tries to tip the bearing rather than simply push it sideways.

The cost is in the increased width the second ball element set adds, so double row ball bearings belong where axial space is available and radial space is not the binding constraint.

Shop Double Row Ball Bearings.

 

 

Double Row Thin Section Ball Bearings

This family combines the two ideas above. Two rows of balls sit within a slim cross-section, giving more capacity and better axial resistance than a single-row thin section bearing while keeping the small radial envelope that made a thin section bearing attractive in the first place. It is a specialised answer to a specific and fairly common problem: a large shaft, a tight radial envelope and a load that includes a tilting component.

Shop Double Row Thin Section 
             Ball Bearings.

 

 

Miniature Ball Bearings

Miniature ball bearings are the same deep groove principle built small, for instrument mechanisms, small motors, dental and medical devices, model engineering and precision prototypes. At this scale, the priorities shift. Running torque, smoothness and consistency between units usually matter more than raw load capacity.

Specify miniature ball bearings where the assembly itself is small rather than simply lightly loaded.

 

Shop Miniature Ball Bearings.

Thrust Bearings for Axial Loads

A thrust bearing is built for load along the shaft axis. Its raceways are arranged as opposing faces rather than as a groove around a shaft, so force pressing along the axis is carried squarely between them.

The applications are the ones where something rotates while supporting a push or a weight in line with its axis: vertical spindles, rotary tables, turntables, screw jacks, lazy-susan style indexing plates and swivel joints. In these cases selecting a radial bearing would be carrying the load in the direction it is least suited to. 

A thrust bearing is not intended to carry significant radial load. Where an application imposes both, the usual answer is to let a thrust bearing take the axial component while a separate radial bearing locates the shaft sideways, rather than expecting one component to do both.

Thrust bearings are among the ranges most recently added to Accu's bearing offering, alongside needle roller and further rolling-element types.

Shop Thrust Bearings. 

 

Needle Roller Bearings for Tight Radial Envelopes

A needle roller bearing uses rollers with a high length-to-diameter ratio: long and slender rather than short and stout. Each needle contacts the raceway along a line, with many needles packed around the shaft. These bearings carry a high radial load and because the needles are slim, it does so within a small radial envelope.

That combination is the reason the family exists. It is the answer to an application that needs real radial capacity where a deep groove ball bearing of sufficient rating simply will not fit the space around the shaft. Gearbox layshafts, compact linkages, rocker arms, universal joints and dense mechanisms are typical homes for it.

The trade-offs follow from the geometry. Line contact means more friction than a ball, so needle rollers favour moderate speeds over high ones. Slender rollers are also less forgiving of misalignment and of an out-of-round or under-hardened shaft surface, so shaft and housing preparation matter more here than with a ball bearing. Needle roller bearings can be combined with Bearing Inner Rings where a shaft is out of specification or made from a ductile material which will not support the bearing face.

Shop Needle Roller Bearings.

 

Plain Bearings and Slide Bearings

Plain bearings work via sliding contact as opposed to rolling. A bush, a collar or a flat pad separates two components and is chosen so that the sliding interface has a low coefficient of friction and wears predictably. There are no balls, no rollers, no cage and no raceways.

That simplicity is the main reason engineers select Plain bearings. With no rolling elements, there is nothing for grit to indent, no cage to fatigue and often no lubrication requirement at all where a self-lubricating material is used. Plain bearings suit low-speed and oscillating duty; they tolerate contamination better than rolling-element bearings and they are quiet, light, inexpensive and compact. What they do not do is match a rolling element for efficiency at continuous speed.

 

Slide Bearings

A slide bearing is the cylindrical form of plain bearing: a bush that sits between a shaft and its housing so the shaft turns or slides against the bush rather than against the housing bore. Use slide bearings on pivots, hinges, dampers, levers and slow-turning shafts, particularly where the duty is intermittent or oscillating and where a sealed rolling bearing would be overspecified for the job.

Shop Slide Bearings. 

 

 

 

Plate Bearings

A plate bearing is the flat form of plain bearing: a thrust washer or pad that separates two faces bearing against one another, carrying load along the axis while allowing rotation or small sliding movements between the two surfaces. Plate bearings are the plain-bearing counterpart to a rolling thrust bearing, chosen where the load is modest, the motion is slow and simplicity is worth more than efficiency.

Shop Plate Bearings. 

Linear Bearings for Straight Line Motion

A linear bearing constrains motion to a straight line instead, supporting a carriage as it travels along a fixed axis shaft as opposed to the rotational motion seen within ball and roller bearings.

The selection logic used for roller bearings transfers directly when looking at linear bearings. The load is still radial or axial with respect to the axis of travel, the environment still decides how tolerant the bearing has to be of contamination and the space envelope still constrains what will fit. What changes is that the running surface is a shaft or rail rather than a ring, so alignment across the length of travel becomes a design consideration in its own right.

Linear bearings commonly feature on slides, actuators, gantries, print and inspection heads, test rigs and any axis where a component has to move along a defined path under load.

Shop Linear Bearings. 

 

Bearing Inner Rings and Shaft Mounting

Some bearings run directly on the shaft rather than on a machined ring of their own. That works only where the shaft surface material is hard enough, round enough and finished to a fine enough tolerance to serve as a raceway, which frequently it is not.

A bearing inner ring solves that. It is a separately hardened and ground sleeve fitted to the shaft, giving the rolling elements a proper raceway without the cost of hardening and grinding the shaft itself. It also lets a worn raceway be replaced as a component rather than as an assembly.

A bearing is only as accurate as the seat it sits in and the shoulder it sits against, so the surrounding parts are part of the specification. Adjusting rings set axial position on the shaft, parallel keys transmit torque between shaft and hub, circlips and retaining rings retain the bearing axially, dowel pins hold housings in alignment and flexible shaft couplings absorb the residual misalignment that would otherwise be passed straight into the bearing.

Shop Bearing Inner Rings. 

Types of Bearings Chart: Load, Speed and Environment Compared

 

Material selection when selecting bearings.

Material choice typically determines how a bearing behaves in its operating environment rather than how it performs under load, often serving as the primary constraint that narrows down a shortlist.

As a general rule, rolling-element bearings rely on metal construction because their raceways demand extreme surface hardness. Conversely, plain bearings offer a much more open material choice because the sliding interface itself acts as the primary working surface.

Protecting these materials from environmental contamination and retaining vital lubrication is the job of bearing shields and seals. Metal shields provide a non-contact barrier against larger debris without adding rotational friction, while rubber seals create a physical contact barrier that offers superior defence against moisture and fine dust at the cost of slight rotational drag. For a comprehensive guide on decoding the exact seal and shield configurations for a specific component, please consult the Bearing Identification Code Table.

A Selection Checklist Before You Specify

Working through the below list of bearing selection criteria can help reduce your options to a single bearing family. Keep these in mind when designing your project or looking at final component selection.

• Load Vector and Ratio: Is the force predominantly radial, axial, or combined? Specify deep groove or cylindrical rollers for heavy radial loads, thrust bearings for purely axial forces, and angular contact or specialist tapered rollers for genuinely mixed loads.

• Motion Profile: Continuous high-speed rotation demands rolling elements to minimise friction. Conversely, slow oscillation or heavy static loads often require plain bearings to prevent false brinelling (wear indentations).

• Spatial Envelope: Evaluate available radial and axial room independently. Specify needle roller bearings if radial space is strictly limited, or thin-section bearings when axial width runs out first.

• Moment Loads: If the assembly experiences twisting or tilting forces, a single narrow bearing is insufficient. You should specify double-row bearings, matched pairs or space two bearings wider across the shaft to support the load and its forces evenly.

• Operating Environment: Standard bearing steel corrodes easily. Wet or chemically aggressive conditions require stainless steel, engineered plastics, or ceramic hybrids. Specify rubber seals (2RS) to exclude moisture, or metal shields (ZZ) for low-friction debris protection.

• Shaft Integration: Using the shaft as an inner raceway saves radial space but requires the shaft to be hardened and precision-ground. Otherwise, using a standard inner ring is far more cost-effective and offers a replaceable wear element at significantly less than a machined part.

• Mounting and Retention: Determine your location strategy immediately. Decide on interference fits, retaining rings, circlips, or machined housing shoulders alongside the bearing specification, not as an afterthought.

 

Wrapping up.

Bearing selection is ultimately a process of strict elimination. By systematically evaluating your load vectors, spatial envelope, and operating environment, a vast catalogue of components quickly narrows to a single, optimal family. 

Whether your design demands the high-speed efficiency of a deep groove ball bearing or the rugged simplicity of a self-lubricating plain bush, defining these physical constraints early in the design phase is the only reliable route to a successful, long-lasting assembly.

Further Reading:

How to measure bearings - Discover the Engineering Science Behind Bearing Codes. 

How to use a calliper - Learn About the Science of Metrology With Accu.

What Is Creep In Materials? - Learn More about Materials Science With Accu. 

 

FAQs.

Q: What is the difference between a ball bearing and a roller bearing?

A: The shape of the rolling element. A ball contacts each raceway at a point, which keeps friction low, suits continuous high-speed rotation and tolerates minor misalignment, but concentrates the force into a small area. A roller contacts each raceway along a line, spreading the load over a larger footprint to give higher capacity and greater stiffness in the same space. The trade-off is more friction and heat, lower maximum speed and much less tolerance of angular misalignment.

Q: How do ball bearings reduce friction?

A: They replace sliding contact with rolling contact. In a plain bush the shaft drags across a stationary surface along its whole contact area. In a ball bearing the balls roll between an inner and an outer raceway, touching each one only at a small point that deforms slightly under load. Because so little material is in contact and nothing is being dragged, the resistance to motion falls sharply for the same duty.

Q: Can a thrust bearing carry a radial load?

A: Not to any significant degree. A thrust bearing has its raceways arranged as opposing faces so it can carry force along the shaft axis, which is the one direction a radial bearing handles poorly. That same geometry gives it little ability to locate a shaft sideways. Where an application imposes both, use a thrust bearing for the axial component and a separate radial bearing to locate the shaft, rather than asking one component to do both jobs.

Q: When should I use a plain bearing instead of a ball bearing?

A: When the motion is slow or oscillating, when the environment is dirty or wet, or when lubrication and maintenance access are limited. A plain bearing has no rolling elements for grit to indent and no cage to fatigue; self-lubricating materials remove the greasing requirement altogether. It is also quieter, lighter and more compact. What it will not do is match a rolling-element bearing for efficiency under continuous rotation at speed.

Q: How can I tell if a bearing has failed?

A: The usual signs are audible and tactile before they are visible. Listen for a rumble, a graunch or a periodic click that rises with speed. Feel for roughness, notchiness or free play when the shaft is turned by hand. Running noticeably hotter than usual, increased vibration or a visible loss of grease all point the same way. Any of these on an assembly that matters is a reason to strip and inspect rather than wait, because bearing failure is progressive.

Q: Do I need a bearing inner ring?

A: Only where the shaft itself cannot serve as a raceway. Running a bearing directly on the shaft saves radial space but demands a shaft that is hard enough, round enough and finished to a fine enough tolerance to take the rolling elements. Where the shaft is a softer or more ductile material, or where hardening and grinding it would be uneconomic, a separately hardened and ground inner ring gives the bearing a proper raceway and turns the wear surface into a replaceable component.