Potholes destroy coil springs
Potholes destroy springs
Coil springs are under attack year round from the road below and spring material is progressively weakened with each successive impact (fatigue). Kilen improve fatigue strength via shot peening and stress relieving which, together with the addition of a zinc phosphate coating, effectively reduce the risk of premature failure. However, every pothole contact adds to spring fatigue, making breakage more likely, and all springs are susceptible to fatigue – even the best made.
In winter, as grit salt is spread on the roads it forms an abrasive paste when mixed with surface water, grinding the protective paint off the spring. Microscopic cracks – a result of fatigue, and which inevitably increase in size over time – become fully exposed to the elements. One of these cracks will eventually propagate, fracturing the spring completely and leading to total failure.
The tensile strength of a spring can be affected by cold temperatures, making it more brittle and increasing the likelihood of breakage. The breakage risk is however significantly bigger with a ‘budget’ quality spring using lower quality steel (containing defects) and without the previously mentioned risk reduction measures employed by quality spring manufacturers.
Anatomy of a pothole
Freshly laid tarmac forms a solid, impermeable barrier between the soft foundation under the road, and the elements above. Over time, with traffic volume acting as a catalyst, the tarmac becomes more porous and rain begins to penetrate the cracks. In winter, the water freezes and expands, pushing the tarmac upwards.
As the ice thaws, gaps appear below the surface and fill with water. These gaps grow larger with each freeze-thaw cycle, and eventually the vibration and weight of the traffic above causes the tarmac to collapse into the void, creating a pothole. The pothole becomes larger and deeper as traffic continues to roll over it.
The Government’s response
In England, road maintenance budgets for 2015/16 have fallen by 16% compared to 2014/15, and the proportion of the total highway maintenance budget spent on structural maintenance is 55%, down from 58% last year. Councils filled just 2.2 million potholes in 2015/16, a reduction of half a million compared with 2014/15.
While local authority’s claim that Britain’s roads are improving – only 13% are now classified as ‘poor,’ down from 15% in 2014/15 – there is still a 14-year backlog requiring £11.8 billion - £88.8 million per local authority in England – which will never be fully cleared. In addition, the percentage of roads in ‘good structural condition’ has dropped from 53% to 48% in the course of a year.
The true state of the roads may, however, be obscured by the fact that 70% of local authorities only declare a ‘pothole’ if the depth is over 40mm, and the majority of roads are assessed by machines that assume good surface condition equals good structural condition.
By only checking surface quality, damage to the underlying layers may go unseen, despite structural damage being the main cause of most potholes. Potholes are often ‘repaired’ by simply patching the road surface, allowing further structural deterioration below.
Potholes, it seems, will continue to support sales growth in the replacement coil spring market for many years to come. Kilen springs, produced in Sweden, are designed to withstand the harshest conditions of a Scandinavian winter. Each Kilen spring is made from the highest quality, specialist spring-steel, and protected from corrosion using the galvanic protection method of zinc phosphating, before being powder-coated with epoxy resin to provide additional protection.
Kilen supply springs to the likes of Volvo, and all Kilen aftermarket springs are of matching OE quality. Kilen provide the quality, range, and service to support sales growth for their customers, and Kilen UK are centrally located and operate a robust distribution network in partnership with many of the country’s largest automotive distributors, covering the whole of the UK and Ireland.
No matter the conditions, the spring you need is never far away! Make sure you’re ready for winter by keeping your Kilen coil spring range up to date.
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