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SHEET LIGHTENING
Page 58
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Aerodynamics is simple: keep the air flow uninterrupted and there is less resistance and improved fuel consumption. CM commandeered a tipper with a sheet to put the theory to the test.
Making a tipper streamlined is a tricky business: the body shape means air first batters the front of the truck, then the tailboard after it dips over the top of the cab. It's even worse if the truck has a grab fitted behind the cab, because that draws air as well.
On top of this, bodies are ribbed for extra strength.The air hits the cab and loops down the side before hitting the last panel of the truck and curling up behind the tail hoard, causing extra drag as it meets the air that has travelled over the top of the cab.
A sheet should improve things as it will keep air moving down the top of the load without hitting the tailboard, helping to reduce drag. The use of sheets, though, is something of a grey area. Rather than enforce sheets for all loads, the legislation leaves the decision to the transport manager.
Emitting dust
The definition is that a tipper should have a cover sheet if any load it is carrying might emit dust into the atmosphere. Failure to adhere to this could result in a £5,000 fine by the relevant authorities.
In the main, aggregate and asphalt tippers are covered and quarries' best practice is to make all tippers leaving their site cover up or risk being expelled.
Muckaway and others who work off varying building sites and move to landfill tend to be cover-free as their load is invariably a combination of mud, muck and heavy stone. These are more likely to throw a stone up from its tyres than emit dust.
With the help of MAN and Thompson we put the sheet theory to the ultimate test. Ignoring the dust issue, could a sheet improve fuel economy out on the open road? •