Types of Bearings: How to Match the Bearing to the Load

A bearing rarely fails because it was a bad bearing. It fails because it was the wrong type for the load, the speed, or the environment it was put into. Every plant runs dozens of different bearing types across its motors, gearboxes, conveyors, and fans. Knowing which one belongs where is the difference between a scheduled replacement and a 2 a.m. breakdown.

This guide covers the main types of bearings used in industrial equipment, what kind of load each one is built for, and how to read a bearing number so you order the right replacement the first time.

Radial Load vs. Thrust Load: The First Question

Every bearing selection starts with the direction of the load. A radial load pushes perpendicular to the shaft, like the weight of a pulley hanging on a motor shaft. A thrust (axial) load pushes along the shaft, like the force on an auger or a vertical pump shaft. Most real-world equipment sees some combination of the two.

Bearing types are built around that distinction. Some handle radial load only, some handle thrust only, and some are designed to carry both at once. Get the load direction wrong and even a premium bearing will wear out early.

The Main Types of Bearings

Deep groove ball bearings. These are the most common bearings in any plant, found in electric motors, fans, and light-duty pumps. They handle moderate radial loads, some thrust in either direction, and high speeds. Sealed versions (2RS) keep grease in and contaminants out; shielded versions (ZZ) allow slightly higher speeds with less protection.

Cylindrical roller bearings. These use cylinders instead of balls, so each roller contacts the race along a line rather than a point. That gives much higher radial load capacity, which makes them a common choice in gearboxes, large motors, and heavy-duty rolls. They carry little or no thrust.

Tapered roller bearings. The rollers and races are cone-shaped, which lets a tapered bearing carry heavy radial and thrust loads at the same time. They’re usually installed in opposing pairs and are standard in gear reducers, wheel hubs, and heavy shaft assemblies. Timken is the name most maintenance teams associate with this design.

Spherical roller bearings. Barrel-shaped rollers in a spherical outer race let the bearing tolerate shaft misalignment and deflection while carrying very heavy loads. That makes them a common pick for vibrating screens, crushers, large fans, and conveyor head pulleys, where perfect alignment is hard to hold.

Needle bearings. These are long, thin rollers packed into a small cross-section. They’re used where radial space is tight but load capacity still matters, as in some gearbox and linkage applications.

Thrust bearings. Ball or roller thrust bearings are built for axial load only: vertical shafts, turntables, and some auger and screw conveyor designs.

What Are Mounted Bearings?

Mounted bearings are bearing inserts pre-installed in a cast or pressed-steel housing that bolts directly to a frame. Pillow block (two-bolt base mount) and flange (two- or four-bolt face mount) units are the most common. For most conveyor, screw auger, and material handling shafts, a mounted unit is faster to install and replace than a bare bearing pressed into a custom housing. That’s why they show up on nearly every feed mill and bulk handling line.

How to Read a Bearing Number

Most ball bearing part numbers follow a pattern. Take 6205-2RS:

• 6 is the bearing type (deep groove ball).
• 2 is the dimension series (light duty).
• 05 is the bore code. Multiply by 5 for the bore in millimeters, so 05 means 25 mm. Codes 00–03 are the exceptions: 10, 12, 15, and 17 mm.
• 2RS means rubber seals on both sides.

If the number on a failed bearing is worn off, measuring bore, outside diameter, and width gets you to the right part. Bring the old bearing in and our counter team can cross it for you.

Why Bearings Fail Early

Most premature bearing failures trace back to a short list of causes:

• Lubrication problems: too little grease, too much, or the wrong type for the speed and temperature. The right grease is covered on our industrial lubricants page.
• Contamination: dust, grain fines, and washdown water getting past worn seals.
• Misalignment: shafts out of line put uneven load across the rollers.
• Improper installation: hammering a bearing onto a shaft damages the races before it ever turns.

Bearings rarely fail on their own, either. A chain or belt running out of tension puts side load on the shaft bearings behind it. If you’re weighing drive options, our chain drive vs. belt drive comparison covers how each one loads the rest of the drivetrain.

Need to cross a worn bearing number or find a replacement fast? Call (919) 777-9807. We stock Timken and Koyo bearings and mounted units in Sanford.

NC-Specific Considerations: Harvest Season Is Bearing Season

Fall is peak season for North Carolina’s grain handling and feed operations. Bucket elevators, conveyors, hammer mills, and pellet mills run long hours through harvest, and that’s exactly when a dry or contaminated bearing gives out. For feed mills around Smithfield and the rest of Johnston County, a pre-harvest bearing and seal check is one of the cheapest insurance policies available. The same applies to processing plants around Raleigh running seasonal volume.

NC humidity is a factor year-round. Moisture that gets past a seal causes corrosion pitting on the races, which is why sealed or labyrinth-sealed mounted units are worth the small upcharge in damp or washdown areas.

Frequently Asked Questions

What are the main types of bearings?
The main industrial bearing types are deep groove ball bearings, cylindrical roller bearings, tapered roller bearings, spherical roller bearings, needle bearings, and thrust bearings. Mounted bearings (pillow block and flange units) package these inserts in a bolt-on housing.

What is the difference between a ball bearing and a roller bearing?
Ball bearings make point contact with the race, which suits higher speeds and lighter loads. Roller bearings make line contact, which spreads the load and gives them much higher load capacity at somewhat lower speeds.

Which bearing handles both radial and thrust loads?
Tapered roller bearings are the most common choice for heavy combined radial and thrust loads. Deep groove ball bearings handle combined loads too, but at lighter capacities.

What does 2RS mean on a bearing?
2RS means the bearing has a rubber seal on both sides. It keeps grease in and contaminants out better than a metal shield (ZZ), at the cost of slightly lower maximum speed.

Getting the Right Bearing on the Shaft

Choosing between the types of bearings comes down to load direction, load size, speed, alignment, and environment. Match those five and the bearing will run its full service life. Cruco Supply stocks bearings, mounted units, and the power transmission components that run alongside them, including Timken and Koyo. Call (919) 777-9807 or stop by our Sanford location with the old bearing in hand.