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Clean green machine

Delivering more for less - construction’s new mantra - means making savings. Can these include consumption of fuel by plant? Yes they can, says Volvo. NCE reports.

You do not have to be Einstein to work out that improved fuel efficiency can have a significant impact on a project’s bottom line. Substantially reduce the diesel consumed by plant on site and the savings quickly feed through. Imagine a wheel loader using 50 litres less of fuel per day on a job that lasts for two years. This amounts to a saving of about 30,000 litres, factoring in holidays and Sundays. Put another way, with red diesel currently selling at around 60p per litre, £18,000 has not been emitted as exhaust fumes. With multiple machines on site, the savings soon reach the six figure mark.

And financial accounting is not the only consideration: carbon accounting also has to be borne in mind. The environmental benefits to cutting fuel consumption include lower resource depletion, few emissions and less heat generation.

So what is the construction equipment sector doing to deliver more fuel efficient machines? Volvo Construction Equipment is making strenuous efforts to “green” its machines, and last month in Sweden, the company held a major event for plant companies and operators to underscore its commitment to improving fuel economy across its entire range.

“We are aiming to boost productivity and profitability for our customers while providing environmental benefits”

Arvid Rinaldo

Among the evidence presented were a number of Volvo’s huge wheel loaders that, says the firm, save up to 15% in fuel. And that is just for starters, according to Volvo Construction Equipment’s global market communications manager Arvid Rinaldo. “We want to announce very emphatically that we are delivering on our promise to improve fuel efficiency,” he says.

“Through innovation we are aiming to boost productivity and profitability for our customers, while at the same time providing environmental benefits.”

The company is mounting a four pronged attack to find solutions in its engines (see box), vehicle systems, operator behaviour and future technology. Volvo’s overall intent is for its products to be market leaders through overall efficiency and least environmental impact, Rinaldo says.

Heading the developments under Volvo’s vehicle systems category is the new “OptiShift driveline technology” being fitted to the aforementioned large wheel loaders. Volvo says that, because it designs and builds its own engine and transmission units, it is able to ensure its mechanical components synchronise and function in harmony; and also that new bits of kit can be made to match and fit in sweetly.

The OptiShift system incorporates two features: a new torque converter and a “reverse by braking” function. A torque converter is typically an automatic clutch and power transmission device sited between the engine and automatic gearbox, which serves to boost substantially the input torque from the engine.

It is a critical component for wheel loaders, especially when driving into a pile of material or accelerating away with a heavy load. A standard torque converter is about 85% efficient, Volvo says. OptiShift’s torque converter increases efficiency to 98%.

Reverse by braking (RBB) is a way of handling more efficiently the deceleration that needs to occur frequently, in short cycle loading, for example. Traditionally it is common for an operator to use the gear shift to change between reverse and forward, rather than applying the loader’s brakes. In effect, the torque converter copes with the deceleration. This puts strain on the converter and raises fuel consumption.

OptiShift’s RBB function automatically uses the wheel loader’s standard brakes to decelerate. “The operator handles the machine in the same way as normal but when they switch from forward to reverse using the gear shift, the RBB function recognises the speed, direction and throttle position and applies the brakes to slow the machine,” says Rinaldo.

“This provides a smoother deceleration and direction change, and since the converter is no longer used for braking, wear and fuel consumption are reduced,” he adds.

Up to 15% fuel savings is the proud boast for OptiShift. Other benefits, Rinaldo claims, are faster loading cycles, increased operator comfort, better drive response, increased hill climbing performance, better deceleration comfort and less loading stress on the transmission.

Volvo is acutely aware of the difference that properly informed plant operators can make, in terms of productivity and fuel consumption. This is why operator behaviour has been put under scrutiny as part of the company’s “green machine” initiative, and why the Eco Operator programme has been launched, effectively to teach fuel efficient and environmentally friendly methods of working.

“The programme teaches plant operators correct machine operation and manoeuvring and also how to plan their work in the most efficient way”

Arvid Rinaldo

“The programme teaches plant operators correct machine operation and manoeuvring and also how to plan their work in the smartest, most efficient way,” Rinaldo claims. “We believe, among other things, that operators are more productive when they slow down and work smarter. Smoother, more deliberate operation also means less stress while maintaining productivity.”

Theoretical training in the classroom plus hands-on experience are included in the Eco Operator training programme, which can be customised to suit companies’ specific requirements. A trainer (often sitting with an operator in his own machine, and not disturbing the day’s planned activity) gives guidance on how to change behaviour, not least in order to save fuel. Skanska is one of the first companies to enroll its operators in the programme.

“In one study, where 37 operatives took part, it was found that fuel consumption reduced by 5% - representing savings of over €250,000 (£207,000) and a reduction in emissions of 500t of CO2”, says Rinaldo, adding that some operatives reduced fuel consumption by 25%.

Tips given to drivers include: keep tyres properly inflated (to reduce wear and fuel), ease up on the accelerator (a lighter foot equals increased productivity), slow down (keep engine speed within the economical portion of the engine speed range), plan the work, cooperate with other plant operators to work together in the most efficient way, do not idle unnecessarily, and use the right equipment for the job.

Telemetrics also come into the Volvo green equation. Electronics are available to log individual machines and their operators in terms fuel consumption, hours worked, fault reports and so on. This kind of information can be used to make comparisons between drivers, and encourage beneficial competition.

The message from the Volvo event is that the group is committed to innovation, and to pushing the plant industry forward in an ever greener fashion, and that its engineers are being encouraged to think out of the box.

“There is an atmosphere in the company to foster lateral thinking,” says Rinaldo. And, as far as Volvo’s construction plant is concerned, “we will be making advances in the future, and these will undoubtedly save more fuel”.

V-act: A green engine

Engine development at Volvo has tended to concentrate on emissions, with the intention of complying with EU 111B off-highway exhaust emission legislation, due to come into effect next year, and similar US requirements.

Other plant engine manufacturers must be doing the same of course. But, as Volvo Construction Equipment is keen to point out, it has the possibility of transferring experience and technology from other parts of the Volvo group, which have developed or are developing low emission solutions for their on-road trucks and buses.

“A veritable cascade of innovations” has been introduced for the new generation V-ACT (Volvo-Advanced Combustion Technology) engine systems, according to Volvo’s communications people.

“The new units feature exhaust gas recirculation, which lowers the amount of oxygen in the combustion chamber, reducing combustion peak temperatures and, in so doing, lowering the formation of nitrogen oxides,” says Volvo Construction Equipment’s global market communications manager Arvid Rinaldo.

An “advanced exhaust after treatment” system is also included, to reduce particulate matter by 90% compared to the previous machine series.

A filter traps the particulates and holds them until there is sufficient build up to merit “regeneration” - incineration of the particulates at temperatures in excess of 700˚C to turn them into ash.
Low sulphur fuels are required for these engines, and specialist engine oil.

“A sophisticated electronic control unit supplies the necessary level of control, in particular managing the whole exhaust gas recirculation process which is crucial to reducing harmful emissions - while also maintaining performance and economy,” says Rinaldo.

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