Timken suspension & steering

Why a wheel bearing is tapered

A ball bearing is excellent at carrying load in one direction and poor at carrying it from the side. A wheel bearing has no such luxury: it holds the weight of the corner of the car, and every time the vehicle turns it takes a large thrust load along the axle as well.

The tapered roller solves both at once. Its rollers and races are cut as sections of a cone, so a sideways force is resolved into pressure along the whole roller rather than a point contact. Timken patented that geometry in 1898 and built a company on it.

For wheel hub assemblies this shows in how the unit ages. A well-made tapered roller unit tends to announce itself gradually with a rising hum that changes as the car is steered, rather than failing suddenly, which gives a driver time to act.

Henry Timken patented the tapered design in 1898 while building carriages in St. Louis, and the company has been headquartered at Canton, Ohio ever since. It still makes its own steel, which is unusual: the metallurgy and the bearing are developed together rather than the bearing being cut from whatever bar stock was purchased.