THE CLEAN AIR ACT

Changes in end-user demands and the implementation of increasingly stringent legislation have moved previously non-vital considerations such as fuel consumption, low noise levels and reduced exhaust emissions, to the top of many OEMs' list of priorities.

Following the trend of the automotive sector, construction equipment manufacturers are now supporting the customer-led demands for quieter and cleaner equipment. Initially limited to the larger end of the equipment spectrum, environmental friendliness is rapidly becoming the buzz word at the smaller end as well.

Belle Engineering claims to be a founder member of the Green Revolution. The company, noted for its design and engineering expertise, arrived on the skidsteer scene in 1977.

Seen as a diversification from the company's core concrete mixer business, the skidsteer range has grown steadily ever since with new models being added in 1990-91 and most recently followed by the 7600 machine in 1992.

The mainstay of the three model line-up is now in fact the 7600 which competes in the 600kg class and accounts for around half of all skidsteer sales. Belle director, Nicholas Taylor, said: 'One of the important factors that sets the 7600 apart from the competition and makes it so acceptable to European customers is its reputation for low noise levels and clean exhaust. Both factors which owe as much to the initial engineering design and manufacture as to the use of a Kubota engine.

'We researched all the possibilities and for us, although we look very hard at cost of every component we buy in, specification was more important than price. Kubota's V2203 E series was the power unit that most closely matched our needs and that is the engine installed in the 7600.'

Kubota was in fact the first diesel engine manufacturer to obtain the Californian Air Resources Board (CARB) certification, acknowledged to be the toughest test in the world. At the moment CARB only applies to engines in the up to 18.75kW class, but with the general trend towards cleaner exhaust emissions and quieter equipment, logic dictates that higher power engines will also need certification in the near future.

Brian Garner, Kubota engine sales manager, says the company made a number of fundamental design changes to meet the CARB standards. 'A huge amount of research work resulted in changes to both shape and dimensions of the combustion chamber and reducing the injection timing delay. Changes to the Three Vortex Combustion System (TVCS) included the E suffix for all four engine ranges.

'E-TVCS takes the TVCS to the next stage of emissions reduction. Offsetting the direction of fuel injected into the swirl chamber and redesigning the throat to match the concave recess in the piston creates greater diffusion in the combustion chamber, reducing soot, unburned HC and CO emissions.

'To improve quiet running, all bearing tolerances, gear tooth meshing patterns, even down to tappet clearances, were all re-assessed and tightened up where possible.

'The fact that the company has put so much effort and research into making engines environmentally clean means that a number of OEMs have changed to Kubota power to sell into California,' said Garner.

As part of the 7600 skidsteer development programme, Belle ran full tests in which both manned and unmanned units were operated for 24 hours per day for 20 weeks.

The unmanned tests with the machine tethered to a central point and allowed to circle the test track are the most severe. 'It would scramble an operator's kidneys in an hour,' said Belle's Taylor.

'Modern computer aided design (CAD) systems means that our design engineers can carry out theoretical testing on componentry, but there is no substitute for real 'in the iron' operation. During the destructive testing, the Kubota V2203 E completed 1,000 hours and inspection showed it had not even developed an oil leak.

'I really believe that choosing the Kubota has materially helped us sell the 7600 in both the UK and overseas.

'Many of our customers use other Kubota-powered equipment, so they know the engine and the back-up that goes with it,' said Taylor.