How it began
Sven Wingquist was head of maintenance at a textile factory in Gothenburg, a city on the west coast of Sweden built on mud. Buildings there settled into the ground and threw machinery out of line. In 1907 he designed a double-row ball bearing that could adjust itself to a misaligned shaft. He patented the principle and founded Svenska Kullagerfabriken, SKF for short, in the same year.
Before it existed
Around 1900, floors settled, shafts bent under load and temperature changes distorted whole machine structures. In a rigid bearing arrangement even a small misalignment could set off friction, heat and costly downtime, and the standard bearings of the time could not cope with it.
How it works
The bearing has two rows of balls and an outer ring whose raceway is part of a sphere. Because the center of that curve lies exactly on the bearing axis, the inner ring and the balls can swivel freely inside the outer ring. The bearing therefore compensates for misalignment, up to about 3 degrees, without generating forces that would hinder it.
What changed first
The design solved the problem of misaligned shafts and was the founding product of SKF. It worked well for light to medium loads. In heavy industry the point contact of the balls was a limit, because the contact surface was too small for extreme loads.
What lasted
In 1919 Arvid Palmgren at SKF kept Wingquist's spherical outer raceway but replaced the balls with barrel-shaped rollers, creating the spherical roller bearing for heavy loads such as railroad wheelsets. Both types are still standard machine elements. Spherical roller bearings are used in paper machines, rolling mills, mining, ship propulsion and the rotor shafts of wind turbines.
