What is the importance of steering alignment and suspension settings to OTR tyres?

Check the front tyres on any haul truck. If there is evidence of uneven wear then there is a high probability that the alignment settings are not to OEM specification. Using a wood rasp grind away some of the rubber from the shoulder lug of a scrap tyre. There is a large energy input for little reduction in rubber volume. This serves to demonstrate how much power is consumed to wear a tyre in an irregular pattern.

An increase in rolling resistance will be observed as a reduction in speed, an increase in fuel consumption and increased mechanical maintenance. Simple checks of toe settings, centre to centre verification of each front tyre assembly, front to rear alignment, and on some trucks camber and caster all contribute to ensuring that not only does the truck steer straight but consumables (tyres, fuel, time) are limited to the minimum actually required.

The advent of gas oil suspensions has enabled trucks to travel over rough ground at higher speeds without shaking apart. The setting of such suspension systems is critical to the operation of the truck. Incorrect oil levels leads to incorrect gassing volumes which leaves the suspension unit out of specification. Each unit should be set using manufacturers recommendations ensuring strict attention is paid to cleanliness, volumes and pressures. Some sites will require further attention to vary the suspension strut settings such as compression and rebound damping orifices, this is beyond the scope of this discussion but be aware it can be done with advantage to the operator.

Steering setting such as toe should be checked at every major service. Most units will require raising to enable the front suspension to be extended to its full travel, where toe is set.

Front to rear & centre to centre alignment ensure that all tyres are running in the same direction. Front tyre assemblies should be centred prior to adjustment, every adjustment made from there to one side shall be made to the other side. If there is difference front to rear that cannot be adjusted out the truck manufacturers should be consulted for relevant advice.

The effects of incorrect steering and suspension settings will observed in the workshop as reduced bearing life, abnormal suspension unit wear patterns, however the tyres will show the wear first, and the worst part? Once the irregular wear has started there is no way to reverse it other than to rotate the tyres to the rear positions.

Tyres are a mirror of the operation, no tyre problems generally indicates there are no maintenance or production issues to reduce production.

If the mirror doesn't reflect an absence of tyre problems then COBA Engineering can assist you to reduce your tyre operation costs and provide the added bonus of increased production!