DON’T LET TYRES COMPROMISE ELECTRIC BUS RANGE
The UK’s new generation of EV and hybrid bus fleets cannot afford to ignore tyre pressures. Pure EV and hybrid bus fleets are now everywhere. From Bristol in the south west right up to Glasgow, every major conurbation in the UK is getting on board with the zero emission movement.
EVs are fast becoming a fixture on our roads. Fleets of electric buses are currently in operation in cities including London, Milton Keynes and York, with operators promoting their increased sustainability and lower running costs. However, poor tyre pressure monitoring could lead to the UK’s fledgling fleet of EV buses suffering from unexpectedly high levels of rolling resistance, which could significantly reduce range capability.
While the issue of tyre maintenance isn’t new to the bus industry, with the arrival of electric buses the problem of increased rolling resistance due to low tyre pressures is exacerbated. A slow puncture can go undetected for weeks in between manual checks. The negative effect on fuel consumption of a diesel bus may not be noticed right away, but on an EV this extra rolling resistance directly affects the ability of the vehicle to complete its journeys between charges. That’s why it’s essential for electric bus operators to adopt a wholesale attitude change when it comes to tyre pressure monitoring. At WheelRight, we advocate daily tyre pressure checks.
Recent statistics published by the US Department of Energy provide some useful insight into the importance of rolling resistance where EV and hybrid buses are concerned. Rolling resistance is the energy lost from drag and friction of a tyre rolling over a surface, and a wide range of external factors can contribute to its impact on vehicle performance. While it is estimated that up to 11% of light-duty fuel consumption for conventional and hybrid electric vehicles is used to overcome rolling resistance, the figure is much higher for larger vehicles such as buses.
Because all-electric passenger vehicles are extremely efficient in energy use, tests show that they use approximately 23% of their energy to combat rolling resistance. Proper tyre inflation plays an important role in energy efficiency. By keeping tyres properly inflated, fleets can improve their fuel efficiency figures by up to 3%. Under-inflated tyres can reduce efficiency by 0.2% for every one pound per square inch (psi) drop in pressure in all four tyres of an average passenger vehicle – and this effect is exaggerated further on buses, as most use six tyres.
We’ve seen first-hand the impacts of standard manual tyre checks on buses of all kinds, especially in terms of rolling resistance and range capabilities. The issue is complicated further by the fact that most buses have inner rear tyres, which are difficult to reach and measure. While there’s no doubt most bus operators have been doing the best they can with the tools available to them, until recently, daily pressure checks have been impractical and expensive. Manual gauges are tricky to use and time consuming, something especially pertinent given the tight turnarounds bus operators work to.
However, the development of drive-over tyre pressure monitoring technology, such as the unique service pioneered by WheelRight, makes daily checking a reality. With an increasing number of bus operators adapting their facilities to incorporate electric buses, they should also use this as an opportunity to include drive-over tyre pressure monitoring technology into depots, to minimise disruption and maximise savings.
A key benefit of the WheelRight system is that it dramatically reduces the amount of time it takes to measure tyres. Far from the laborious manual method, WheelRight’s system checks the pressure of every tyre on a bus in just 6 seconds as it drives through the depot – meaning the vehicle doesn’t have to be taken out of service or even deviate from its usual route through the depot.
Furthermore, because every tyre on every bus (EV or otherwise) is checked as it enters or exits a depot, we instantly inform fleet managers of potential problems before they escalate and affect safety and energy efficiency. Such data will also provide fleet managers with valuable long-term trend analysis to ensure they maximise efficiency, safety and the passenger experience.
To find out more, just get in touch with me and I’ll be pleased to help.