Trailer brakes are not renowned for their efficiency or, with the negligible maintenance they receive, for their reliability. But this could now change if new EC braking requirements are imposed. Andy Collings reports.

Tractors have become larger, faster and more sophisticated but trailers are still very much as they were over 30 years ago. In short, trailer development has fallen ever further behind that of the tractor that pulls it, particularly in the brake department.


                  
Credit: © FARMERS GUARDIAN please contact 01772 799445.
The majority of trailers are going to require better braking systems to offer more stopping power.


That is the view of research scientist Dr Andy Scarlett, whose latest project is aimed at raising user awareness of the inadequate performance of many agricultural trailer braking systems – and, he says, provide guidance regarding the practical means and economic viability of putting things right – should they need it.

Dr Scarlett was speaking at an IAgrE Agricultural Transport Conference held in Peterborough last week, a conference attended by a generous number of trailer manufacturers, representatives from tractor companies, the HSE, BAGMA, AEA plus several brake system designers.

Concentrating the minds of delegates was the news that proposed EC braking requirements were likely to exceed, by some considerable amount, the braking ability of most current trailers – both old and new.

Such improvements in trailer braking efficiency would of course be welcomed by tractor manufacturers who have had to deal with an ever increasing demand for brake failure warranty claims brought about by inadequately braked trailers and other trailed implements relying on the towing tractor’s brakes to provide the stopping force.

If there was need for further reason to improve trailer braking, the HSE reports that transport accidents represent a third of all agricultural fatal incidents – 84 people have been killed in agricultural transport accidents during the last six years.

The EC Directive proposals and the Transport Research Laboratory recommendations are that:

• Trailers need to have 50 per cent braking efficiency rather than the current 25 per cent.

• There should be no design speed categories – everything with brakes must achieve a minimum 50 per cent braking efficiency.

• Failsafe braking system that are activated when the trailer accidentally parts company with tractor.

• Trailer parking brake to be applied from the tractor seat.

• Trailed equipment over 3,500kgs total axle load will require same braking system as trailer.

• Trailer and trailed equipment braking systems will require Type Approval testing before they can be sold.

Because trailers are operated from tractors, there are also new proposals for tractors. However, most modern tractors already comply, in the main, with them.

Should these proposals be accepted it is likely they will become a national requirement for new tractors and trailers by about 2010 which, for trailers at least, means the vast majority are going to have to be constructed with braking systems which offer greater stopping capacity.

Most UK agricultural trailers are fitted with braking systems designed to operate within the 20mph (32kph) UK speed limit for vehicles without suspension. Which is at odds with the fact that the vast majority of tractors are now capable of 25mph (40kph) and more than a few can manage 30mph (50kph).

However, the demands on the braking system multiply dramatically – increasing speed from 20mph to 30mph increases the energy dissipation requirement by over 140 per cent which means that trailers with 20mph brakes hauled at these speeds soon suffer terminal brake wear.

                        

Credit: © FARMERS GUARDIAN please contact 01772 799445.
Dr Andy Scarlett

Dr Scarlett suggests it is more economical in the long-term to buy a trailer with the required braking specification or fit an existing trailer with suitable running gear, than pay out what could be over £2,000 to repair the tractor’s oil immersed brakes.

Having the correct brake system with adequately sized brakes is only part of the equation – albeit an important part. Equally essential is to provide the correct maintenance schedule to ensure they actually continue to work.

With his trailer-testing programme not due to end until May it is perhaps too early to draw any firm conclusions but the indications are that all is not well in trailer braking.

The full results are due to be available in July – and should make interesting reading.


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