What are the most common reasons a heavy goods vehicle (HGV) fails its MOT? Brake issues, headlamp outages and steering mechanism faults are all up there, and it’s time to address the latter. In this article I want to explain the growing need for bespoke steering systems for long-distance HGVs.
On average, a long-distance HGV will travel around 125,000 miles each year. These lengthy distances, often carrying varying loads, can put significant strain on a vehicle and its steering system. Off-the-shelf steering systems for HGVs are usually developed to fit a certain size of vehicle – whether that’s a 7.5 tonne truck or a 44-tonne artic. What isn’t always considered is the application, load and environment which the vehicle will encounter.
Consider this as an example. A vehicle primarily used for motorway driving will not require the same steering agility as a truck that’s driven on A-roads and B-roads – which generally has more variance in camber and elevation. Similarly, if a HGV is required to drive internationally, it must be equipped to deal with varying weather conditions, particularly if the destination is renowned for low temperatures or icy roads.
Agility in steering systems is particularly important for long distance HGV drivers and those that are travelling across the continent. European road freight transport is increasing year on year and is currently at the highest recorded figure. On average, these vehicles carry out distances between 30 and 1,200 miles at a time, sometimes travelling between extremely different climates and road conditions.
In these instances, off-the-shelf steering systems do not suffice. To alleviate this challenge, HGV OEMs are turning to made to measure steering systems with custom design. These systems are not only manufactured with a specific vehicle in mind, but are also tested vigorously to ensure they can withstand the environment in which the vehicles will operate.
During the development of a prototype steering system, the OEM can request to put the system through an intense physical testing procedure. Depending on the testing facilities of the steering manufacturer, this can simulate several repetitions of driving cycles, to a figure set by the customer. This figure can depend on the application and what they require.
The required application will dictate what kind of environmental testing also needs to take place. For example, salt spray testing can simulate certain road environments and the associated debris, testing for smoothness and changes to torque in varying temperatures and salt concentrations.
Testing can also be used to simulate varying loads or forces the vehicle may encounter, enabling the OEM to establish an accurate fatigue life of the parts within the system and provide a greater insight into the lifespan of the steering system. This is particularly beneficial for long distance HGVs and can avoid unexpected problems with steering when the vehicle is in another country, or in a difficult to reach location. Generally speaking however, steering parts made the correct way should outlive most other parts in a vehicle.
This requirement is also driving demand for low maintenance steering systems. When HGVs are likely to be away from depot for long periods of time, choosing a low maintenance steering system can provide reassurance that the related parts will not fail or encounter any problems when travelling far distances. This is particularly important for vehicles travelling to remote locations, such as the transport of mining and quarrying products, which can span from one side of the continent to the other.
For situations like these, OEMs should choose a steering system that offers high levels of ingress protection. Pailton Engineering, for example, prides itself on producing steering systems that go the distance. Due to the enclosed casing of its systems’ bevel boxes, the oil inside the system remains intact, as it is not exposed to outside elements. This engineering can expand the lifespan of the entire system.
In Britain, where HGVs export 3.7 million tonnes of goods and import 4.2 million tonnes each year, it is vital that these vehicles are designed to withstand long journeys. For lorries manufactured to take on this challenge, OEMs should invest in bespoke steering systems, not only to improve the agility of the vehicle, but to prolong its lifespan thanks to long lasting vehicle parts and reduced MOT failures cause by steering system issues.
Posted on: November 22nd 2018