Ball bearings create a point of contact between the ball and ball path with the rolling element to minimize surface contact, reducing friction and heat. They provide high-speed operation but are better suited for lower load capacities.
Types of Bearings: Selection Guide
Explore the most common types of bearings used across industries. Learn how to choose the right bearing based on load type, speed, housing, and misalignment needs.
What Are Bearings Used For?
Bearings allow shaft rotation while minimizing frictional losses and/or supporting the shaft and its associated loads. They are typically selected based on expected life (in hours), which is impacted by the applied load and rotation speed.
Common Applications
HVAC: Blowers, fans, roof vents, air curtains
Food & Beverage: Conveyors, mixers, fillers, packaging systems
Material Handling: Baggage systems, parcel conveyors, warehouse distribution
Construction: Pavers, off-highway vehicles, highway stripers
Agriculture: Mowers, bailers
Aggregate & Mining: Conveyor and idler pulleys, radial stackers
From construction bearings built to handle off-highway shock loads to the mounted bearings used throughout material handling and conveyor systems, matching the housing and locking style to the application matters just as much as matching the bearing type itself.
Key Bearing Terms
Basic Dynamic Rating: The American Bearing Manufacturers Association (ABMA) defines it as the constant radial load that 90% of an identical bearing group with a stationary outer ring can endure for 1 million revolutions (33 1/3 RPM for 500 hours). A basic dynamic rating is not the maximum load that should be applied to the bearing.
Static Radial Rating: The American Bearing Manufacturers Association (ABMA) defines static radial load rating as the load that causes permanent deformation of the rolling element and raceway in the bearing.
Radial Load: Load applied perpendicular to the bearing bore.
Axial Load (Thrust Load): Load applied parallel to the bearing bore.
Speed: Measured in Revolutions per Minute (RPM); higher speeds reduce bearing life and increase heat.
Types of Bearings
Bearing Misalignment Considerations
Static Misalignment: This occurs due to fixed installation issues like uneven mounting surfaces between two bearings. Most ball and tapered roller bearings have minimal internal alignment tolerance. However, mounted ball and tapered roller bearings may offer some self-alignment capability between the housing and bearing inserts.
Dynamic Misalignment: Occurs with ongoing alignment changes, like bent shafts. Both ball and tapered roller bearings have very limited internal misalignment capabilities. However, spherical roller bearings are better suited for this due to their internal misalignment capability.
Locking Mechanisms for Bearings
Single Set Screw: Secures the bearing to the shaft with two screws on one side of the inner race.
Eccentric Locking Collar: Provides a collar with an eccentric lip that mates with an eccentric lip on the inner ring bearing. Turning the collar while holding the shaft and inner ring results in a “cam” action that locks the collar and inner ring to the shaft. (Eccentric lock is not recommended for reversing rotation applications.)
Concentric Locking: Uses collars or tapered sleeves to center the shaft in the bearing bore and virtually eliminate the lock-induced bearing out-of-roundness found with eccentric or setscrew designs. This reduces vibration and shaft run-out during operation, as well as eliminating shaft marring.
These bearing locks, set screw, eccentric collar, and concentric collar, are the three most common ways to secure a bearing's inner ring to the shaft, and choosing between them usually comes down to how much precision and vibration resistance the application demands.
Bearing Housing Types
Pillow Block
Most common bearing housing. Available for light, normal, and medium-duty applications.
Two-Bolt Flange
Flush-mounted with two bolt holes. Best for lighter loads.
Four-Bolt Flange
Flush-mounted with four bolt holes for higher stability.
Flange Bracket Bearing
Narrow housing with three bolt holes on one side of the housing. Best used in very tight spaces and tail pulleys.
Stamped Steel
Stamped steel housings typically consist of two steel halves that mate together and clamp the bearing insert. These are available in both pillow block and flange designs.
Tapped Base Pillow Block
Designed for use where shafts are close together.
Insert/VER Unit
Designed to mount inside a customer’s housing. No self-alignment capability.
Frequently Asked Questions
In everyday shop terms, an eccentric bearing usually refers to a mounted bearing, like a pillow block or flange unit, that locks onto the shaft with an eccentric locking collar rather than a set screw. The collar's off-center lip creates a cam action that clamps the inner ring to the shaft when turned, which is different from a true eccentric bearing design used in cam and vibrating-screen mechanisms, where the outer race itself is intentionally offset from center.
Concentric locking uses a collar or tapered sleeve that stays centered on the shaft, which keeps the bearing running true and cuts down on vibration and shaft marring. Eccentric locking uses an off-center collar that creates a cam action to clamp the inner ring in place. It's simple and effective for one-direction rotation, but it isn't recommended where the shaft reverses direction.
A set screw is the simplest option, securing the bearing with two screws bearing down on one side of the inner race, but that off-center pressure can throw the shaft slightly out of round. An eccentric locking collar spreads the clamping force more evenly around the shaft through its cam action, giving a more secure hold for higher-vibration applications, though it isn't the right choice for shafts that reverse rotation. Neither is as precise as a concentric locking collar, which is the better option when minimizing runout matters most.
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