1907: Sven Wingqvist and the Birth of SKF

In 1907 a young Swedish engineer named Sven Wingqvist patented a bearing that tolerated misalignment. The idea was simple and the consequence was not: a bearing that self-aligns removes the requirement for a perfectly rigid, perfectly aligned shaft and housing, and that single change unlocked whole classes of machinery. The company founded to make it, Svenska Kullagerfabriken, became SKF, and its history shaped the global bearing landscape more than any other single enterprise.

This article explains the problem the 1907 patent solved, why mill drives and textile machinery adopted it first, how the company grew into a family tree of manufacturers, and why the SKF designation system became a de-facto reference language in catalogues everywhere. It ends with the checks a buyer still runs today: suffix codes, clearance and fits.

The problem: misalignment destroyed single-row bearings

A single-row ball bearing assumes that the shaft and the housing are concentric and parallel. In real machines they are not. Shafts deflect under load, housings are bored slightly off-axis, and long shafts sag between their supports. When that happens, the bearing's inner and outer raceways are no longer aligned, the ball load concentrates on one edge of the raceway, and the bearing fails early.

The remedies available in 1907 were expensive and inflexible: build a stiffer shaft, machine a more accurate housing, or shim and adjust on assembly. All of them move the problem into the structure rather than solving it in the bearing. A bearing that could absorb a few minutes of angular misalignment by itself would remove that cost from the design.

Wingqvist's 1907 patent

Wingqvist's design used two rows of balls running on a spherical outer raceway, so the outer ring could tilt relative to the inner ring while the balls stayed in contact. This is the self-aligning ball bearing: it carries radial load, tolerates angular misalignment of up to a few degrees depending on size, and runs quietly where a rigid single-row bearing would fight the shaft.

How the self-aligning design works

The outer ring's raceway is a section of a sphere, and its centre coincides with the bearing centre. When the shaft deflects, the outer ring simply rotates within its housing, and the contact between balls and raceway is maintained. The load path stays clean, vibration falls, and the bearing keeps its calculated life.

Why mill drives and textile machinery adopted it first

The first customers were the machines that suffered most from misalignment. Line-shaft drives and mill machinery ran long shafts through multiple bearings on supports that moved under load. Textile machinery ran many closely spaced spindles where a small alignment error in each one produced heat, noise and thread breakage. For both, a self-aligning bearing was not a refinement but a fix.

Those two sectors were exactly the right beachhead. They were large, they were demanding, and they were familiar with bearing failure, so their engineers could see the difference immediately. A breakthrough bearing makes its reputation in the industries that already understand why bearings fail.

The founding of SKF in Gothenburg

The company was founded in Gothenburg in 1907 to produce the design, and it grew quickly beyond its original market. Within a few years it was exporting, and it opened manufacturing operations abroad rather than only shipping from Sweden. Those foreign operations are the reason the industry's family tree runs the way it does.

From one factory to an international network

Building plants near the customer reduced freight and lead time and improved service, so SKF established subsidiaries in several countries. Each subsidiary needed local engineers, and each trained a local manufacturing workforce. That is how a single Swedish company seeded bearing-making capability across Europe.

Exporting from one Swedish plant would also have limited the company to markets it could reach by sea at acceptable cost. Building locally changed the economics: freight and lead time fell, service improved, and each plant became a source of engineering talent for its own region. The knowledge behind the bearing, not just the bearing itself, travelled with the product, which is why the company's influence on the industry was structural rather than merely commercial.

The SKF family tree

An unusually large share of the world's bearing manufacturers can be traced, directly or indirectly, to SKF's early international operations. Subsidiaries were set up in several countries, and in some cases they later became independent national manufacturers with their own brands and their own product ranges.

Which manufacturers grew out of SKF operations

The pattern is well documented in broad strokes: SKF's foreign plants and their spin-offs became, over decades, some of the strongest national bearing enterprises. The practical consequence for a buyer is that many designations and suffix conventions in the market share a common ancestor, which is why they look more alike than they would if they had been invented independently.

The SKF designation system as a reference language

Because SKF sold into so many markets so early, its catalogue language became familiar far beyond its own products. Buyers, distributors and machine builders learned to read suffixes such as 2RS for a two-sided contact seal, C3 for extra internal clearance and W33 for a lubrication groove and three holes in the outer ring. Those codes then appeared, with local variations, in other makers' catalogues.

Indicative suffix meanings. The letters and their combinations vary between manufacturers, so confirm each one against the catalogue you are actually buying from.

Suffix families and what they mean

A suffix is an attribute, not decoration. Two bearings with the same base number and different suffixes can have different friction, different speed limits, different allowable temperature rise and different protection against water and dust. The base number fixes the envelope; the suffix fixes the behaviour.

What the suffix does not tell you

A suffix does not tell you the load rating, which is the manufacturer's own figure, or the steel and heat treatment behind the rating. It also does not tell you the ball or roller grade. Cross-referencing by suffix alone is as incomplete as cross-referencing by base number alone.

• The base number gives the envelope: bore, diameter series and width, all fixed by the ISO 15 boundary tables.
• The closure suffix gives the seal or shield type, and therefore the contamination protection and the speed limit.
• The clearance suffix gives the clearance band, which must suit the operating temperature rise.
• The cage suffix gives the cage material, and therefore the temperature and speed ceiling.
• The precision suffix gives the running accuracy class under the ISO 492 tolerance limits.

Clearance and fits: the two choices that decide life

Clearance and fit are the two selection decisions that most often decide whether a correctly sized bearing gives its rated life. Internal clearance, standardised in values such as C2, CN, C3 and C4 under ISO 5753, is the total gap between rings and rolling elements. A bearing installed with a tight interference fit loses some of that gap because the rings are compressed, and a hot running position loses more as the shaft expands faster than the housing.

Reading a Designation the 1907 Way

The 1907 patent solved an alignment problem, and the industry never stopped reading bearings through the naming system that grew around it. A step-by-step check still works the same way it did a century ago: read the design, then read the attributes.

1. Read the base designation for the envelope, and confirm bore, outside diameter and width against the ISO 15 boundary tables.
2. Decode every suffix in the designation, because each one changes friction, speed or protection.
3. Pick the clearance class for the temperature rise, using the standard values rather than habit.
4. Calculate the fit from the load direction and the ring that rotates, using the ISO 286 system rather than a rule copied from another job.
5. Confirm the running accuracy class against what the machine actually needs.
6. Cross-reference on attributes, not on the name, using the interchange lookup.

The detail behind each step is covered in our guides: the seal and shield suffix guide, the internal clearance guide, the shaft and housing fits guide and the designation guide. For the family that started it all, see the self-aligning ball range and the self-aligning ball guide; for the workhorse of almost every machine, see the deep groove ball range. The brand is covered on our SKF page, and the wider market on the brand directory.