Steering Column Operations: Part 1 - Design Features

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Subject:
Steering Column Operations

Topic:
Steering Column: Part 1 - Standard Steering Column Design Features

Objective:
Identify by name the design and major components of vehicle steering columns and explain how these features influence vehicle rescue operations

Task:
Given vehicles of different makes and models, name the type of steering column and explain how components of the column can influence vehicle rescue operations

Experience shows us that the most effective method of freeing a driver trapped by the dash, firewall, instrument panel, and steering column is for a rescue team to either roll the dash or jack the dash. These evolutions move the steering wheel and column, pedals, dashboard, and firewall all at once. There are, however, some situations where rescuers may have to revert to an "old" way of doing things: pulling the column. Remember those days? Hooking up a power spreader or a come-along with a set of chains and pulling a steering column seems to have become a lost art among rescuers.

One scenario in which jacking or rolling may not be effective for column movement is when a seated and belted driver is trapped in a side-resting vehicle that is positioned with its driver's side down. Think about it. In this position, jacking or rolling does not work well for several reasons; the driver's door cannot be opened and there is no way to cut the driver's-side A-pillar to make relief cuts.

Because rescue teams still have the possibility of working directly with chains wrapped around a steering column to rescue a trapped driver, it is important that rescuers recognize the different designs of steering columns found in vehicles. This University of Extrication series of articles on steering columns will look at the different types of steering columns and focus on reviewing the seemingly lost art of column pulling.

Standard Steering Column Design

At a crash scene where a driver is trapped by the wheel and column, one rescuer should be assigned to look closely around the patient's leg area and near the brake or gas pedals. An effort should be made to determine the type of steering column. During extrication work, the type of column design can have an influence, either positively or negatively, on the extrication process. Additional features such as tilt or telescoping controls can also have an effect on the extrication of the trapped driver.

The rescuer may see a continuous metal shaft or housing coming down from the steering wheel and extending through a hole in the floorboard or firewall structure. If this is the case, the column is most likely a standard one-piece unit.

The standard steering column design consists of a continuous shaft cold-rolled steel rod at the inner core of the steering column. This design is the oldest and is most commonly found on older vehicles. The cold-rolled steel shaft attaches to the steering wheel bracket at its uppermost end. At its lower end, the shaft attaches to linkages in the engine compartment that allow the front wheels to steer as the steering wheel is turned.

In an extrication situation when rescue personnel are pulling this style of steering column up and away from a trapped driver, the standard column design is resistant to bending. It typically takes a minimum of 4,000 pounds of pulling force to move the column away from a trapped patient. In the old days of chains and come-along tools pulling a column, the chains had to be rigged properly or else the pull would not be effective.

Tilt and Telescoping Steering Column

Another steering column design feature that has been around for a long time is the tilt or telescoping steering column. Rescue personnel working with a trapped driver challenge must recognize that the column has a tilt or telescoping feature. The tilt feature is now considered the norm as a standard feature on late-model vehicles. Its presence can be used to the benefit of the medical and rescue personnel when dealing with a trapped driver. Operating the tilt feature can provide additional clearance between the driver and the steering wheel or column. That is important when the column is being moved. If there is sufficient clearance, the column will move away from the patient. If the patient is in direct contact with the steering wheel or the steering column, then the initial movement of the column may in fact move towards the patient before it begins to move clear of them. Operating the tilt or telescoping feature may provide a slight clearance, enough to remain clear of the driver's torso as the column moves.

A telescoping column consists of a sliding shaft and housing at a point near the dashboard and instrument panel bracket. Sliding this telescoping feature allows the length of the steering column to be adjusted to suit the comfort of the driver under normal conditions. In a rescue situation, the column may be able to be shortened to once again provide clearance as the column is moved by the rescue team.

A tilt steering column has a knuckle joint situated several inches above the instrument panel. This connection typically consists of a plastic ball on the lower side with the upper steering column having a set of curved metal fingers. These fingers grab and hold onto the plastic ball in various positions from low to high, thus providing the tilt column feature.

Rescue personnel should attempt to operate a tilt feature into the high position if this will provide additional clearance between the trapped driver and the steering wheel and column. In addition, if a steering column is to be cut through in a total removal assignment, this plastic swivel joint is a weak section of the column that the cutters can readily cut through.

Part 2 of this series on steering columns will look at the design and operation of a rack-and-pinion steering column. Also addressed will be a unique new steering column design available in Mercedes-Benz vehicles.

Part 3 will focus on the step-by-step procedures for pulling a steering column with chains and a power spreader or come-along tool to free a trapped driver when the vehicle itself is side-resting, driver's-side down.


Ron Moore, a Firehouse contributing editor, is a battalion chief and the training officer for the McKinney, TX, Fire Department. He also authors a monthly online article in the Firehouse.com "MembersZone" and serves as the Forum Moderator for the extrication section of the Firehouse.com website. Moore can be contacted directly at Rmoore@firehouse.com.

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