TRACTION TO THE POWER OF THREE

The author of this article argues that lorry manufacturers and operators should be paying more attention to double-drive and weight-saving, now that the use of three-axle tractive units is increasing rapidly. Though the current UK lorry weight limits have now been in force for over three months, it is still difficult to be sure of some of their practical consequences. It is already apparent that the attraction of three-axle tractors for articulated combinations with large payloads rose dramatically as a result of their relatively low vehicle excise duty (ved) rates. This is all part of the Government's policy to encourage lorries with more wheels, to spread their load more evenly over the road. Three-axle tractors have strong technical as well as tax advantages in their favour. They have little risk of axle overload, can interchange with a wide variety of semi-trailers, and can work at 44t train. They have more effective and safer braking than two-axle tractors. The case of three-axle tractors is even stronger when axle weights in various common situations are compared. Their one obvious weakness at present is poor traction, but the new regulations could help to improve this, for example through a financial incentive to encourage two axles, especially if the second axle is steered as well as driven.