One Lump or Two
By Malcom Bates
Next to the regular collection of domestic waste, there is perhaps no better sign of a civilized society that the cleanliness of its streets. But there's a heated debate-taking place at present, between the exponents of traditional twin-engine truck-mounted highway sweepers and those who suggest that a single engine format is the way forward. This debate is a complex one, but there are signs that the single-engine concept is gaining ground.
From an engineering viewpoint, perhaps the only vehicle that could be said to be more complex than a truck-mounted highway sweeper is a compact, purpose-built 'precinct' machine. Alongside refuse (garbage) collection and disposal vehicles - themselves amongst the most difficult to operate vehicles - suction sweepers have to operate in one of the toughest environments of any manmade machine.
As the essential function of the highway sweeper is to collect litter, dead leaves and other debris from the road surface in order to prevent roadside drainage gullies becoming blocked - or in some parts of the world where tourism is a major industry, just to help keep the highways looking picture-postcard clean - it goes without saying that the one single ingredient likely to be common to all operating conditions is dust. And lots of it.
In order to keep down the clouds of dust that would otherwise occur during sweeping, an on-board water spray system with as high a capacity as possible is clearly desirable. Dust and water together? These two ingredients have to be amongst the most damaging substances to allow near any machine. But one packed full of complex electrics and hydraulics? It's harder to think of a more demanding application. So any design improvements that can rationalize componentry, or reduce complexity, has to be worth consideration, especially if they could save on manufacturing and assembly costs and promote greater reliability in service at the same time.