Big claims for active-steer on trailer axles

The Department for Transport-commissioned study into longer semi-trailers has taken a potentially significant development, with the promotion of advanced new trailer steering technology.

Turn-in, swing-out and tyre wear characteristics of the current standard, 13.6m long semi-trailer could be not only matched but slightly improved even if the trailer length were increased to 15.6m, it is claimed. That would overcome one of the objections to longer semi-trailers - although many other issues would remain.

The so-called "active steering" technology add around 1.2 tonnes to a tri-axle bogie and, as very provisional indicative maximum figure £5-6,000; and could be brought to market well within two years, we understand.

This option is one of three basic types on which the study is focussing. The others are: a low-cost longer semi- similar the Kögel Big Maxx, which allows extra 1.3m in length using fixed axles but would most likely be limited to between 38 and 40 tonnes; and an extension of around one metre, using a single self-steering axle. All three options are being treated equally by the DfT and its researchers. However, it seems clear that the Kögel Big Maxx concept has limited appeal for the UK. Of greater interest to some hauliers and to the DfT is likely to be the concept of rear-steer axles with technology currently available and likely to be brought to market in the near future.

It is clear that active steering could be of interest to those specifying trailers at the current 13.6 length, or shorter, due to the promise of improved performance - although weight and cost would remain an issue.

A leading exponent of active steering is the Cambridge Vehicle Dynamics Consortium, which has demonstration video on its website at: http://www.cvdc.org/movies/active_steering.html. Members of the consortium include Volvo, ArvinMeritor and Qinetic. RHA member Dick Denby is also a member.