Steering column

From Wikipedia, the free encyclopedia
1 steering wheel
2 case
3 Steering column (hidden by the case - blue dashed line)
4 Universal joint

The automotive steering column is a device intended primarily for connecting the steering wheel to the steering mechanism.

Secondary functions[edit]

A steering column may also perform the following secondary functions:

  • energy dissipation management in the event of a frontal collision;
  • provide mounting for: the multi-function switch, column lock, column wiring, column shroud(s), transmission gear selector, gauges or other instruments as well as the electro motor and gear units found in EPAS and SbW systems;
  • offer (height and/or length) adjustment to suit driver preference

Steering lock[edit]

Modern vehicles are fitted with a steering lock which is an anti-theft device. It is fitted to the steering column usually below the steering wheel. The lock is combined with the ignition switch and engaged and disengaged either by a mechanical ignition key or electronically from the vehicles electronic control unit. These locks were introduced on many General Motors products in 1969 drastically reducing thefts of these GM models,[1] and on Ford, Chrysler, and AMC products in 1970.

Collapsible column[edit]

A common device to enhance car safety is the collapsible steering column. This is designed to collapse in the event of a collision to protect the driver from harm. The column can collapse after impact with a tolerance ring inserted between the inner shaft of the steering column and the external housing. The wavelike protrusions on the circumference of the tolerance ring act as a spring to hold the two parts in place in normal driving conditions. At a specific level of force, for example in the event of a collision, the tolerance ring allows the inner shaft to slip inside the housing, so the column can collapse, absorbing energy from the impact.[2]

In virtually all modern vehicles, the lower section of the inner shaft is articulated with universal joints which helps control movement of the column in a frontal impact, and also gives engineers freedom in mounting the steering gear itself.

Regulatory requirements[edit]

In the United States, steering columns are governed by several federal regulatory requirements, notably FMVSS 108, 114 and 208. The Chinese directive GB15740- 2006 obligates Chinese car manufacturers to incorporate anti-theft mechanisms in their vehicles.[3] European Union Commission Directive 95/56/EC (1995) mandates all cars exported to European markets must be fitted with anti-theft security devices. This regulation also requires that a steering lock must be able to withstand forces of 100Nm applied to the steering wheel without failing.[4]


  1. ^ "The Popular Science Anti-Car-Theft Device Competition" Popular Science", July 1969, p.70.
  2. ^ "Collapsible Steering Column Relies on Tolerance Rings". Machine Design. Retrieved 2017-03-10.
  3. ^ "GB 15740-2006 English version, GB 15740-2006 Protective devices against unauthorized use of motor vehicles (English) - Code of China". Code of China. Chinese Government. Retrieved 2017-03-10.
  4. ^ "EUR-Lex - 31995L0056 - EN - EUR-Lex". Retrieved 2017-03-10.