Commercial vehicle equipment provider AES UK Ltd has urged fleets to ensure that due attention is paid to the wheel alignment on rear axles, as well as on front-steered axles in order to avoid a range of related issues.
“It’s a common belief that tyre wear issues on a front-steered axle is solely caused by incorrect wheel alignment on that particular axle; however, 80 per cent of the tyre wear issue is likely to be caused by the rear axle/s,” warned the company.
“As a theoretical principle your truck’s drive axles can be likened to the steering wheels of a forklift. If the steering wheels on the forklift point to the right, the forklift goes to the left. Applying the same principle to a truck, the driver then has to steer the vehicle to compensate for the misalignment of the drive axles.
“Using this principle, on the diagram you will see a vehicle setup as stationary (left-hand picture), paying close attention to the drive axle and the blue arrow. Using the same vehicle and wheel angles, we now can see what happens when the vehicle is driven (right-hand picture).
“Because the drive axle is pointing to the left, the vehicle wants to go to the right; this in turn causes the driver to counter-steer the truck to the left. Additionally, this is one of the causes of vehicle ‘crabbing’ or ‘dog-running’which means the vehicle takes up more room on the road than it needs to.
“The effects of this are multiplied if the vehicle has trailer attached, and also if that trailer has incorrect alignment settings. “
Effects of misaligned rear axles highlighted by AES include the need for steering compensation; the vehicle taking up too much road space; increased accident risk; increased tyre wear, in some cases also on attached trailers; increased fuel consumption; and driver fatigue.
“In summary, it’s not enough to just be checking a front-steered axle: a full picture of the vehicle’s wheel angles is what’s needed to perform a wheel alignment accurately,” said the firm.
“Whether you’re having alignments done by external contractors or have your own equipment it’s crucial to measure all axles to get the best out of your vehicles from a fuel and tyre perspective. “