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This article highlights the main components and functions of a commercial truck's steering system.

When you think about the steering system of a truck, your mind automatically turns to its steering and front wheels. Yet, several unseen components translate the action on the steering wheel into the truck's movement.

While commercial vehicles are heavy machines, the steering system enables the driver to control and manoeuvre them with minimal effort. The steering system limits fatigue by amplifying the driver's efforts and compensating for the vehicle's weight. 

This article highlights the main components and functions of a commercial truck's steering system. Read on if you would like to find out more about how truck steering systems work.

Components of a truck steering system

While a commercial vehicle steering system consists of several components, we can categorise them into four groups as follows:

  1. Steering wheel assembly
  2. Steering mechanism
  3. Steering linkages
  4. Power steering system 

Expounding on the function of the above groups of components will help explain how commercial vehicle steering systems work. 

Steering wheel assembly

The steering wheel assembly consists of the components truck drivers directly control. They include your steering wheel and steering column. 

To initiate a turn, the driver rotates the steering wheel in a radial motion, which triggers the transverse movement of the wheels. Truck manufacturers use a steering ratio to determine the relationship between the motion of the steering wheel and its wheels. 

The typical steering wheel ratio of a commercial truck is 20:1. This ratio means that a 360 degrees turn of the steering wheel translates to about 18 degrees of rotation on the wheels. A lower steering ratio increases a driver's energy to turn the truck.

Steering mechanism

Today's most common steering mechanism is the rack and pinion system. The pinion is a radial gear attached to the bottom of the steering column. The pinion fits into a worm gear mechanism called the steering rack. 

When the steering wheel is rotated, the cogs of the pinion and rack gears mesh to translate rotary into linear motion. The steering rack connects to the wheel assembly through the steering linkages. 

Steering linkages

The steering linkages absorb the motion of the wheels relative to the steering mechanism. This relativity gives the driver more control over the vehicle. The condition of the road and the action of shock absorbers mean the wheels need some flexibility relative to the steering mechanism. 

The steering linkages provide pivot connections that facilitate relative motion between the wheels and the steering mechanism. Below is a list of some of the steering linkage components.

  • Tie rods
  • Steering arm
  • Pitman arm
  • Drag link
  • Ball joint
  • Kingpin assembly

Power steering system

The power steering system reduces the force necessary to turn your truck's steering wheel while maintaining its steering ratio. There are three types of steering systems in use today. These are:

  • Hydraulic system
  • Hybrid system
  • Electric system

The hydraulic power steering system uses highly compressed hydraulic fluid to amplify the driver's action on the steering wheel to turn the wheels. The hydraulic system relies on a hydraulic pump that is driven mechanically by the truck's engine.

The hybrid power steering system combines hydraulic and electric power to drive the steering system. It relies on a hydraulic pump driven by electric actuators in your truck's engine. 

The electric power steering system is the most reliable of the three. It uses a series of electric sensors and motors to drive your truck's steering system.

To sum up, truck steering systems rely on the efficient operation of several components. Yet, the failure or damage of any steering component can lead to fatal road accidents. Today, maintenance and repair of complex steering systems are simplified with ready access to aftermarket parts for European trucks in Australia.