Spherical Bearings – Accommodating Misalignment
Spherical bearings come in many different types to accommodate a wide variety of applications. What all of them have in common is the ability to accommodate misalignment from mounting or shaft deflection.
- Spherical Ball Bearings
- Spherical Roller Bearings
- Spherical Plain Bearings
- Spherical Rod End Bearings
How Spherical Bearings Work
Regardless of the type of spherical bearing, they all have the same working principal. They all have outer rings that with concave (spherical) inner raceways. The inner rings similarly have convex outter raceways (or rolling elements that create a matching convex sliding surface). What separates the various types of spherical bearings is the design of their sliding surface. Some are ring-to-ring (such as spherical plain bearings and rod ends), others use rolling elements such as balls or rollers between the inner and outter rings.
The animation to the right shows how a spherical ball bearing can reposition the balls and associated inner ring within the outer raceway to accomodate a mis-alignment with the shaft.
Spherical Ball Bearings
More commonly known as Self-Aligning Double Row Ball Bearings, spherical ball bearings are designed to work in applications where severe misalignment exists whether from mounting or shaft deflection. The concave raceway of the outer ring in combination with two rows of balls operates over a wide range of contact angles. Furthermore it aligns itself correctly with the shaft and assembly without causing undue stress on the rest of the bearing assembly. Noteworthy is that the self-aligning ball bearing has the lowest friction of all rolling bearings, which enables it to run cooler even at high speeds. Furthermore, the design allows for easy mounting and dismounting. Visit our section dedicated to Self-Aligning Double Row Ball Bearings for more information about Spherical Ball Bearings.
Spherical Roller Bearings
Spherical Roller Bearings are designed to work in applications where severe misalignment exists whether from mounting or shaft deflection and with relatively heavy radial loads and some axial loads in either direction. They are also extremely resistant to shock loads and their self-aligning feature allows full capacity loading despite shaft deflection. They are very similar in purpose to Self-Aligning Double Row Ball Bearings, except the Spherical Roller Bearings are designed to be more robust by carry heavier loads but at lower maximum speeds. Visit our section dedicated to Spherical Roller Bearings for more information.
Spherical Plain Bearings
Spherical Plain Bearings (also known as "Spherical Plane Bearings" "Spherical Ball Bushing Bearings" and "Ball Bushings") are spherical bearings that have an inner ring with a sphere convex outside surface and an outer ring with a correspondingly sphere, but concave inside surface. Their design makes them particularly suitable for bearing arrangements where alignment movements between shaft and housing have to accommodate, or where oscillating or recurrent tilting movements must be permitted at relatively slow sliding speeds. Visit our section dedicated to Spherical Plain Bearings for more information.
Spherical Rod End Bearings
A Rod End is spherical bearing that consists of an eye-shaped head with integral shank forming a housing and a standard spherical plain bearing, or a spherical plain bearing inner ring, or a spherical plain bearing inner ring and a sliding layer between the bore of the head and the inner ring. As the name implies, they are used at the end of rods and have either a male or female thread for mounting. Visit our section dedicated to Rod End bearings for more information.
Which Is Best for Shaft Misalignment?
If you need help in selecting how to best accomodate for shaft misalignment and which products may be best for your particular application, please remember that design engineering and application assistance are available from AST as part of our value-added services designed to make your job easier.