SPHERICAL BEARING

What Is a Spherical Bearing?

Spherical bearings feature an inner ring that can misalign relative to the outer ring, a result of the curved (spherical) raceway. This design enables the bearing to automatically adjust when the bore axis and housing seat are misaligned. This ensures uniform load distribution, minimal friction and maintenance even under severe operating conditions.

The benefits of spherical bearings are:

• Self-aligning characteristics to accommodate shaft deflection and misalignment
• Lower friction than non-alignment bearings with misalignment
• Good life expectancy and low maintenance in suitable applications
• The ability to take both radial and axial loads, depending on the type

Spherical Roller Bearing: High-Load Performance

The spherical roller bearing is a common bearing type used in industrial applications. This bearing type has two rows of barrels-shaped rollers that operate on a common spherical outer raceway. This configuration enables the bearing to withstand heavy radial loads and moderate axial loads in both directions - a feature not commonly found in other bearing types.

Spherical roller bearings are offered in a number of internal designs, such as symmetrical and asymmetrical roll profiles, and with pressed steel or machined brass cages. A spherical roller bearing has a self-aligning capability which ranges from 1° to 2.5° of misalignment and can be used in applications where the shaft is flexible or the housing distorted.

Typical Applications:

• Paper and pulp industry
• Conveyors and crushers for mining
• Wind turbines, rolling mills, and gearboxes
• Ship propulsion and off-road equipment

Spherical Roller Thrust Bearing: Axial Load Specialist

A spherical roller thrust bearing is designed to support primarily axial (thrust) loads, but can also accommodate some radial loads. It comprises a shaft washer, housing washer, barrel-shaped rollers and a cage. The rollers are positioned equidistantly around a common spherical center, enabling the bearing to align itself and accommodate angular misalignment - a characteristic not commonly observed in typical thrust bearings.

The key difference between the spherical roller thrust bearing and conventional thrust bearings lies in its capacity to handle high axial loads and angular misalignment, all in a single compact unit. It is the ideal bearing solution where vertical shaft configurations, loads and misalignment are present.

Common Use Cases:

• Vertical pumps and compressors
• Ship propeller thrust blocks
• Hydroelectric turbines and generators
• Crane hooks and turn tables

Spherical Plain Bearing: Articulated Motion Solutions

A spherical plain bearing is a plain bearing that operates on the principle of sliding contact. It features an inner ring with a spherically convex surface and an outer ring with a spherically concave surface. The design enables the inner ring to tilt, rotate and oscillate within the outer ring to allow for multi-directional articulation in a compact design.

Spherical plain bearings are offered in maintenance-free versions (with PTFE-lined or composite sliding surfaces) and conventional (lubricated) versions. The ability to handle large amounts of misalignment (up to 10° or more) make the spherical plain bearing a common choice for linkages, control arms and structural joints that require continuous or oscillating angular motion.

Primary Industries & Applications:

• Steering and suspension systems in vehicles
• Farm equipment and hydraulic cylinders
• Construction equipment linkages and pivots
• Airplane actuators and landing gear pivots

Choosing the Right Spherical Bearing: Quick Comparison

The key factors influencing bearing selection include load, speed, misalignment, and operating environment. Here's a quick guide:

• Spherical Roller Bearing: Best for heavy combined radial + axial loads; moderate-to-high speed; 1°-2.5° misalignment
• Spherical Roller Thrust Bearing: Best for high axial (thrust) loads with moderate radial; low-speed, vertical shafts; self-aligning
• Spherical Plain Bearing: Best for oscillating, tilting or rotational movement; high misalignment; maintenance-free designs
• Spherical Bearing (General): General term - self-aligning, axial & radial loads; depends on subtype

Conclusion

Whether you need a spherical roller bearing for a heavy-duty conveyor, a spherical roller thrust bearing for a vertical pump, or a spherical plain bearing for a flexible joint, the common feature of all types of spherical bearing is self-aligning. This makes the spherical bearing family one of the most versatile and reliable bearing types available.
When selecting any spherical bearing for an application, keep in mind operating load size and direction, shaft rotational speed (RPM), anticipated misalignment, lubrication and operating environment (temperature, contamination, moisture). Seek guidance from a bearing engineer or review the manufacturer's bearing load rating tables to ensure a proper fit for the application.