Biffa cuts fuel bills by specifying different axle ratios

Research by Allison Transmission has revealed that many commercial vehicle fleets could cut their fuel consumption by requesting different axle ratios to those routinely offered on new vehicles. This simple change to a truck’s specification costs nothing yet can significantly reduce running costs and carbon emissions. Savings will likely be most significant on duty cycles with frequent stop-starts around town or on minor rural roads.

UK waste management company Biffa recently worked with Allison to determine optimal axle settings for Mercedes-Benz Econic refuse collection trucks with 270-, 300- and 350-horsepower engines. By running simulations on its industry-leading iSCAAN software program, Allison identified that switching these trucks from the standard 6.84:1 axle ratio to a shallower 6.0:1 ratio, also offered by Mercedes-Benz, could reduce fuel consumption by up to 3%, as well as lowering cab noise.

As a result, Biffa has amended its current order of 20 new Mercedes-Benz Econic trade waste collection vehicles, due to be delivered this autumn, with a further order of 18 to follow in spring 2023.

Reducing fuel consumption

Other simulations by Allison have shown that adopting axle ratios numerically lower than those offered as standard by OEMs can reduce fuel consumption by 1-3%. This can be achieved without negatively affecting the vehicle’s launch gradeability or productivity thanks to Allison’s Continuous Power Technology, which nearly doubles engine torque at launch and delivers power to the wheels without interruption when shifting.

‘Vehicle OEMs typically offer their fleet customers a choice of two or three factory-fit axle ratios and recommend one of these according to the country of use and application, making a sensible balance between performance and economy,’ said Nathan Wilson, Allison’s UK Account and Market Development Manager. ‘Historically, a deeper axle ratio setting has been the default selected by OEMs to provide the best gradability for a 30 and above incline. While this delivers a good fit for many customers, in reality, gradients of this extreme are rarely encountered on UK roads. Meanwhile, the pressure to reduce costs and environmental impact has taken centre stage in recent years.’

‘Allison works relentlessly through a consultative approach with end-user customers and OEMs to help them save fuel and lower CO2 and other noxious emissions considering climate change concerns. As a result, we recommend axle ratio reviews when ordering new vehicles, which in most cases will not cost any more to buy, yet will cost less to own and operate,’ said Wilson.

‘We work with organisations like Allison to make sure we get the best advice to optimise our vehicles’ drivetrains, intending to reduce fuel consumption, CO2 emissions and total cost of ownership, without any loss in vehicle productivity,’ said Darren Judd, Biffa’s Head of Fleet Development. ‘As a rule of thumb, every one per cent fuel cost saving equals a 100 rpm reduction. This might not sound like much, but it all adds up over many vehicles and years.’

Allison’s iSCAAN (internet System for Computerised Application Analysis) program optimises vehicle configurations, evaluates vehicle acceptability, and predicts vehicle performance for more than 20 vocational applications. Through matrix analysis, iSCAAN quickly evaluates changes to driveline ratios and shift calibration features. Furthermore, through simulation tools, iSCAAN evaluates the performance or fuel economy of Allison features, such as Acceleration Rate Management and FuelSense 2.0.

In 2021, Allison announced the retrofitting of its FuelSense 2.0 software to Dennis Eagle and Mercedes-Benz Econic trucks operated by Biffa. This aftermarket order, now at 540 trucks, the largest of its kind within the EMEA region, followed a six-month trial in which Biffa found that FuelSense 2.0 Max delivered fuel savings of up to 9% and a reduction of approximately 4,500 kg of CO2 per year. This equates to roughly a £600,000 reduction in fuel expenditure per annum.

In 2020, Allison revealed that savings of £200,000 per year on truck transmission servicing costs were planned to be achieved by Biffa because of advice provided by Allison to extend intervals for the renewal of transmission fluid and filters on its Dennis Eagle trucks. In addition, Biffa predicted savings of 3,600 hours in labour and vehicle downtime annually.