How Do Collapsible Steering Columns Work?

A collapsible steering column is a mechanism that is used to transfer energy from the steering wheel into the steering gear box, which transfers energy to turn the wheels of a vehicle. Though the designs for steering columns have varied since their inception, a typical collapsible steering column looks like two interlocking shafts that attach directly to the steering wheel and the steering gear box. The steering column is the shaft directly under the steering wheel in which the ignition and automatic shift levers are often located.

When the steering column was first invented, it consisted of a single, long, steel rod connecting the steering wheel to the steering gear box. While this single-piece construction was efficient, and effective in controlling the vehicle, it soon became apparent that its design was unsafe in frontal collisions. Under the single-piece system, when such an impact occurred, the steering column would often impale the driver as it was rammed toward the rear of the vehicle.

The unsafe attributes of single-piece steering columns called for the invention of a safer steering column design, which is why Bela Barenyi designed the collapsible steering column to replace it. The safely enhanced construction of the collapsible steering column, no matter which design is used, absorbs, rather than transfers, frontal impact energy by collapsing or breaking upon impact. In this way, drivers involved in frontal impact collisions are able to avoid the dangers of non-collapsible steering parts.

Collapsible steering columns still consist of a long shaft that connects the steering wheel to the steering gear box. However, the collapsible design is composed of an inner and an outer sleeve, pressed tightly together with a number of steel bearings in between. These steel bearings are pressed into the metal sleeves, and are held in place with a strong safety resin, which is designed to harden and then shatter when a specific level of pressure is applied.

In the event of a frontal impact, the steel bearings between the sleeves break free, allowing the inner sleeve to be moved further into the outer sleeve in telescopic fashion before enough pressure is achieved to ram the whole steering column into the driver. In this manner, the energy received through a frontal impact is completely absorbed by the steering column's collapsing parts, allowing most modern drivers to remain completely unaware of the danger they have avoided.