A long wait for 40-tonners? continued from page14 Last week's
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Council meeting also accepted. as working outlines. the Luxembourg Minister's proposals for vehicle dimensions. These largely follow the Commission's proposals, and are: 18m maximum train length for drawbar trailer
outfits. I 5.5m for articulated vehicles (making 40ft container transport simpler) and 12in for rigid vehicles.
A power-to-weight limit of 7 bhp per tonne was also accepted, though Germany still wants 8 bhp per tonne. France reserved its position on the proposed dimensions, including, a width limit retained at 2.5m (8ft Ifin.) and a height limit of 4m.
Germany suggested that artic length should be based partly on turning circle ability. while Holland (which has a 50-tonne gross limit) asked to be allowed to retain a domestic weight maximum higher than the Community figure. The Council agreed to decide before January 1 1978 on the national limits to be applied from 1985.
A five-axle artic
The Technical Editor writes: The combination of an 11-tonne axle limit and a 40-tonne gcw means that "the European truckwill need a minimum of five axles. In articulated vehicle form it will be a three-axle tractive unit with a two-axle semi-trailer, The loading of the tractive unit is such that two light axles and one 11-tonne driving axle will be the most likely solution.
Assuming a tractive unit weight of 7 tonnes and a semi-trailer weight of 6 tonnes a useful payload of 27 tonnes (26.5 tons) will be possible. The semi-trailer bogie will take 20 tonnes and the king-pin load would be 13 tonnes. To cope with this, either a "Chinese six" or a rearsteer design would suffice.
The extra third axle need only be carrying a maximum of 5 tonnes (say) and could thus be single-tyred and suitable for steering. Many European vehicles already fit this pattern, notably the Mercedes-Benz LPS 2024. and could be up-rated the necessary 2 tonnes with little trouble. Existing EEC recommendations suggest a maximum of 3.5 times the weight on the driving axle or pair of driving axles — which. if adopted, would limit gcw to 38.5
tons, unless maximum-weight vehicles had two driving axles.
The road train
The truck and trailer combination for this weight (40 tonnes) would take the form of a three-axle rigid and a two-axle drawbar trailer. The truck would have two 11-tonne axles and gross at 24 tonnes, and would pull a 16-tonne drawbar trailer.
The suggested power-to-weight ratio of 7 bhp per tonne means that a minimum 280 bhp engine is needed and at the moment this is larger than any engine produced by a British truck manufacturer. However, Rolls-Royce and Cummins do offer engines in this range and higher.
No decision has been taken at this stage on turning circle maximum and minimum dimensions but it is possible that figures similar to the current German requirements will be adopted. This could have the effect of making the drawbar outfit more popular and of introducing steering axles on articulated semi-trailer bogies: these are already popular in some European countries.