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ON
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AaIcon is about to introduce an extrawide front axle wheel for trucks, with a 1 1.75"-wide rim. This is wide enough to accommodate 385/65R22.5 tyres---these are said to improve initial cost, handling and tyre life (see page 34).
The one-piece forged aluminium wheel has a load rating of 4,50()kg, and will become available towards the end of April.
Alcoa has also introduced ALclean, a cleaning liquid designed especially for aluminium wheels. It is available in a one-litre spray bottle and larger refills—a complementary polishing compound will be available by mid-1996.
perhaps one of
the most striking new developments came at the Amsterdam CV show where Dutch manufacturer Prins Dokkum's composite Dynawheel attracted considerable domestic and international interest.
It's made from a blend of carbon and aramid fibres, several different synthetic resins plus steel reinforcements around the stud holes.
Heat dissipation might be seen as a potential problem area but Prins says its Dyriavvheel has a high insulation factor and with increasing use of disc brakes and retarders brake temperatures will be reduced anyway
Another plus-characteristic is its elasticity which will counter any minor impact damage.
Aramid fibres are expensive at present so prices will be around 15% more than aluminium ones—however, this will
come down as a demand becomes established. Prins claims a 32kg advantage over a conventional steel wheel and 5kg on an equivalent aluminium one.
The design (which can be colour pigmented) is still under development and awaits its TOY approval but in two months' time Norfolk Line will begin trials with them.
The first production versions, for 22.5in "wide single" tyres, will emerge from the new Dokkum factory by November and other sizes will come on stream next year. W
almost no require
ment for these tyres on truck steering axles," says Leyland Daf. "Normal steering axles can be fitted with tyres up to 315/80 R22.5 allowing 7.5 or even 8.0 tonnes with the right load index. Wide singles will normally make turning circles worse and could put the vehicle over legal width."
Mercedes and ERF have mixed views: "It would be a strange request," says a Mercedes spokesman. As far as I know it's happened once, with an operator involved with turf deliveries specifying wide-singles on a 1617. It can be done but we would refer it to our spe cial products department; we wouldn't offer them straight off the production line."
ERF accepts that "there is an operator demand. ERF markets itself on a bespoke solution but we wouldn't fit anything which would be detrimental to the vehicle's performance. We're tending to see wide-singles more on Olympic-type cabs, which suggests that demand is coming from owner-drivers and high-mileage hauliers. It's a subject which needs evaluating further; there's no problem with fuel economy and the weight disadvantage is slight."
Steering axle
The tyre manufacturers point out that, as they have gone to some trouble to develop tyres specifically for steering axle applications, operators would be well advised to follow their advice: "A lot of technical work, research and development has gone into making wide singles work as efficiently as possible on trailer axles," says Bridgestone Tyre's Roger Moulding. "Therefore we would not recommend their use on any other axle. I would argue that operators would be advised to use the proper product for the proper application. Using the right tyre for the right job addresses not only ride quality and general performance factors, but also the safety issues which arise out of using non-standard equipment."
However, this view cuts little ice with Paul Kuske of Ashford-based PK Commercial Tyres. "I've recommended fitting wide-singles to operators as a cure to a number of problems," he reports. The camber pushes all of the weight towards the outer edge of the tyre which results in dropped shoulders. Fitting wide singles results in increasing road contact—from 220mm to over 300mm—which reduces the transfer problem. My only reservation is that if manufacturers wanted to see their vehicles being operated this way they'd one with its original tyres and fitted the other with 385/65 R22.5 wide singles. The unit with the line-fitted tyres returned 157,391km while the wide-single-equipped unit ran for 228,954 km. Because we're a very high mileage company we tend to assess tyre wear in terms of time rather than distance; on that basis the widesingle-equipped Volvo ran for eleven months without change; the unit equipped with its original tyres ran for only six months."
One of Taylor's main concerns when he first opted for the wide-single configuration was warranty cover: "We spoke to the manufacturers because I was a bit worried about possible problems with the steering mechanisms," he says. "They couldn't see any problems. The only things you have lobe a bit wary of are the fact that you need to use 120' offset rims and you need to get the wheels properly balanced."
Mid-lift pusher
Jimmy Yuili Another benefit that Taylor derives from fitting wide singles is the fact that he can now standardise across all six axles. "New tyres go straight on to the steering axles," he says. "After this they can be recut for the mid-lift pusher axle and, finally, they get sent away to be remixed for trailer use. We're effectively getting three tyres for the price of one, while only paying the same price as a normal 220."
The effect of fitting an eight-legger with wide-singles is less spectacular. Clydebankbased Whiteinch Demolition is running with wide singles on one of its vehicles and managing director George Beattie is quick to point out problems: "We've been trying super-singles on MAN and Mercedes eight-wheelers over the past six months," he says. "We started the experiment because wide singles make the vehicle look more presentable."
Time off road
Whiteinch's business requires its vehicles to spend a lot of time off road, and this has proved to be a problem: "The tyres have done us no harm," says Beattie. "The trouble is that we get more than our average share of punctures, and wide singles just aren't really suitable for the operation. We rarely get a full life out of any tyre so it's hard to tell if we are getting better wear figures. More to the point, it's not that easy finding space to carry a spare on an eight-wheeler."
Another pioneer of this configuration is Strathaven-based Yuill & Dodds. Jimmy Yuill runs a mixed fleet of artics and eight-wheelers and has tried Bridgestone 385/65 R22.5 wide singles on the steering axles of both types of vehicle. "On tractive units we have had no problems," he says. "As long as you can get the vehicle's tracking set up properly they work fine—we put a set on an ERF unit last May and they have only just worn through. That vehicle is up and down the motorway every day and 10 months' wear isn't bad."
Ile is less impressed with the results on his eight-wheelers. "With tippers, Wide singles aren't so good," he says. "For a start they're too easily damaged when you take the vehicle off-road. When the vehicle's laden, they perform reasonably but when it's empty you lose a lot of traction. Slowing down for roundabouts in wet weather with an unladen eightwheeler fitted with wide singles needs a lot of care."
Fitting wide singles to the steering axle is not the answer for every operator. Taylor and Yuill's experience with long-distance vehicles suggests that there are considerable savings to be made but operators specialising in shorter distances over harsher terrain may not be so lucky.
E by Oliver Dixon