RSS Feed

Related Articles

Related Categories

Life’s a low-emissions gas for Hardstaff and Mercedes-Benz

20th May 2011 Print
Mercedes-Benz Actros

A new fleet of 31 Mercedes-Benz tractor units is helping innovative haulier and gas fuel pioneer Hardstaff Group to slash both fuel costs and exhaust emissions.

The Nottinghamshire-based company has developed a dual-fuel – diesel and natural gas – system in conjunction with Mercedes-Benz.

As well as powering Hardstaff’s own vehicles, this can now be specified by any operator ordering a new truck – dual-fuel vehicles are sold and supported by the Mercedes-Benz dealer network in the UK.

Hardstaff’s latest order comprised five Actros 2544 MegaSpace premium long-haul tractor units and 26 Axor 2543s with high-roofed sleeper cabs and optional PowerShift automated transmissions. All were supplied by local dealer Mertrux and some are funded by Mercedes-Benz Financial Services.

The new arrivals have joined a fleet of just over 100 trucks, more than 60 per cent of which are powered by natural gas technology.

The operator’s patented Oil Ignition Gas Injection (OIGI®) system works hand-in-hand with the existing diesel drivetrain. Put simply, it automatically reduces the amount of diesel injected into the engine, replacing it with the same energy equivalent of natural gas.

Gas burns significantly cleaner than diesel but needs a high temperature to initiate combustion – which has previously restricted its use to spark-ignition engines. But the Hardstaff system overcomes this issue by mixing both fuels in the cylinder head, with the compression of the diesel providing the initial ignition which then also burns the gas.

The injection equipment is able to vary the amount of gas metered into the engine – known as the substitution rate – depending on operating conditions and engine load. Starting from cold, and moving off, power is supplied by 100 per cent diesel but gas can be introduced from as low as 620rpm and as the vehicle reaches cruising speed, substitution rates of up to 70 per cent are commonly achieved.

It also works without the need to access the engine’s existing electronic management system so the integrity of intelligent vehicle systems such as braking control and other safety features is not compromised.

Crucially, the substitution of gas for diesel happens seamlessly, with no discernible effect on the vehicle’s performance. Even the engine note is unchanged and from the driver’s seat a small dashboard light is the only thing that confirms gas injection is underway.

Conversion work, which includes the fitting of gas injection hardware, an additional electronic control unit, filling equipment and tanks to hold the compressed (CNG) or liquefied (LNG) natural gas fuel, takes place in Hardstaff’s workshops at its Kingston-on-Soar site, and the process typically takes three days. Various options are available, depending on the vehicle type and application – on long-haul articulated units, for example, gas tanks can be fitted to both tractor and trailer to maximise storage capacity and range.

Steve Storrar, Hardstaff’s Vehicle Applications Manager, said: “The advantages of the system are both environmental and economical.

“If you reduce the amount of diesel being burned, and replace it with methane, you get a significant reduction in regulated exhaust emissions, while gas is about half the price of diesel in most countries.

“Obviously there’s a cost to the conversion work, and the time it takes to recoup that investment varies dependent on the application, the typical diesel mpg being achieved, the estimated average gas substitution, and the mileage being covered by a vehicle.

“Taking all of these factors into account we use a detailed spreadsheet to show potential customers the fuel cost savings, reductions in emissions, and estimated payback period they can expect to achieve. On average the cost of the conversion can be recouped in one or two years.”

Hardstaff’s workshop has been granted ‘Authorised Repairer’ status by Mercedes-Benz UK, allowing customers with converted vehicles to benefit from the convenience of a ‘one-stop shop’ arrangement for all their servicing and maintenance needs.

For more information, visit

More Photos - Click to Enlarge

Mercedes-Benz Actros