The ABCs of D-trains

by N. Royce Curry

BURLINGTON, Ont. – With fuel prices continuing to ratchet up and environmental controls tightening down, longer vehicles may become much more common in the coming years.

One card left unplayed thus far is the concept of a D-train. Double 28.5-foot trailers of any sort offer increased cargo capacity – some 18 per cent compared to a 48-foot unit.

The downside of running trains has always been the driver training necessary to safely use these combinations. According to some, this could be eliminated, or at least reduced substantially, through the use of D-train doubles.

The working name designation for this concept vehicle comes from three existing double configurations making up the present complement of multi-trailer systems:

A-trains use a single hitch attachment and converter;

B-trains have a single piggyback 5th wheel;

C-trains offer a twin hitch attached converter;

but, D-trains would have rigidly coupled tractor with either an A or B converter.

This arrangement is attached to the tractor and positioned some six inches from the back of the cab. Existing components remain the same with only a few exceptions.

The tractor, with its longer wheelbase, will improve the ride characteristics. While the trailer, equipped with moveable sliding dolly jacks will restrict the yaw rate or articulation.

Due to the close coupled trailer, air turbulence is reduced giving way to an improved fuel economy – estimated to be as much as 20 per cent.

Since D-train doubles would behave similarly to a straight truck and trailer, no propensity to jackknifing exists and therefore a substantially safer and more stable unit would result.

All who ply the roads will understand that in every likelihood, fuel is only going to cost more in the future. D-trains may offer, at a minimal cost, an exciting potential for productivity gains in the future. n


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