Martin Phippard Collection - B-Trains, Interlinks and B-Doubles

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by Martin Phippard

Described in the simplest terms a B-Train consists of two trailers linked together by a fifth wheel. This is located at the rear of the first, or lead trailer, and is usually mounted on a “tail” section commonly located immediately above the lead trailer axles. When linked together to form a twin-trailer combination or B-Train set, this may be coupled to a tractor unit via the tractor’s fifth wheel in the customary manner.

The big advantage of the B-Train configuration is its inherent stability when compared to other twin trailer combinations and it is this feature above all else that has ensured its continued development and global acceptance. Relatively little research into the origins and evolution of the concept is apparent and perhaps surprisingly there are still some countries where the advantages of the B-Train have been neither recognized nor exploited.

Although known as a B-Train in several countries, this particular twin-trailer combination is also known by the term Interlink in South Africa and as a B-Double in Australia. I have been fascinated by this particular configuration since I first got to drive one (a tanker combination in Canada headed up by a GMC Astro SS) in 1978 and have since driven examples in Sweden (Volvo F12 plus gull-wing curtainsiders) where they are relatively rare, in Zimbabwe (Scania 112E curtainsider) when I made a run to Beira in Mozambique in 1987 and in Holland where I had a very brief spell recently at the wheel of the Scania 4-Series that heads up the famous KOV Combination B-Train.


Before embarking on the history of the B-Train, it may be prudent to examine the terminology used to describe it and other twin-trailer combinations. An excerpt from a U.S. DoT document published in 1997 reads as follows:

"The common double configuration is called an A-Train. It is similar to a regular tractor/semi-trailer combination with a following full trailer. The ‘full’ trailer is usually composed of a single or double-axle dolly (‘A’ dolly) that has a drawbar that connects to the rear of the first semi-trailer and has a fifth wheel mount for the second semi-trailer. The drawbar of the dolly is usually fitted with a pintle ‘eye’ that connects to the pintle ‘hook’ which is mounted at the rear of the first semi-trailer. A second semi-trailer is hitched to the dolly-mounted fifth wheel. Brake and electrical lines join the two trailers.

International A-Train taken in Israel American A-Train - USF Reddaway International A "semi-plus-pup" tanker from South Africa. Klaus Werblow Collection.
Smart Peterbilt 362 cabover at the front of a South African semi-plus-pup tank combination. This system evolved mainly because weights and dimensions were increased to allow the use of bigger combinations and one of the cheapest ways of increasing the payload of an existing tractor-trailer rig was simply to pull a small "pup" trailer behind the existing outfit. Klaus Werblow Collection.

A Western double (U.S.) is an A-Train with two equal-length (up to 28-feet) trailers with an overall length of 65 to 68-feet (20 to 21-metres). In Canada the maximum length is 25-metres. Turnpike double is a U.S. term for a combination composed of a tractor and two 45-feet long trailers. These are used in the Western United States and on some Eastern toll roads (e.g. The New York Thruway and Florida Turnpike). Another combination is called a Rocky Mountain double and this is a tractor with both a 45-feet trailer and a 27/28-feet trailer. These, as the name suggests, are used in the Western U.S. States.

International DCO-405 with Doubles Brockway Turnpike Doubles Canadian Freightways Rocky Mountain Doubles

A B-Train has a special lead trailer with a rear-mounted fifth wheel. The B-Train is favored by Canadian regulations because of its increased dynamic stability and higher payloads for the same overall length. The second trailer is coupled to the fifth wheel at the rear of the first trailer. B-Trains have more yaw stability and roll coupling (stability) than others. B-Trains are allowed higher loads in Canada. B-Trains are usually special-purpose machines that remain together as a pair.

B-Train Slide (Canadian) KW 900 plus loaded lumber train

The C-Train is similar to an A-Train except that two drawbars are used to eliminate the freedom to rotate about a vertical axis at the hitch point. The dolly is equipped with self-centering, self-steering axle(s) that require a side force of about 0.3g to steer. Canadian regulations allow slightly higher loads on C-Trains than on A-Trains."

Detail of C-Train hook-up by Univision of Biggar, Sask. Mexican KW T800 plus C-Train Vans in mountains Freightliner and C-Train chip vans from Longview, WA. filmed in Morton, WA. in 1990

As may be seen from the above, even the U.S. DoT struggles to define with absolute clarity the various configurations used regularly within its own home territory. And there is no attempt to elaborate on the various differing types and styles of B-Train combination in use. However, these areas will be more fully explored in the following pages.


It is widely, though it seems mistakenly assumed, that B-Trains originated in Canada. In fact in New Zealand where the configuration has been in regular use for about 20-years, the combinations were frequently referred to as “Canadian-style doubles” or “Canadian-style B-Trains” when they first started to appear on that country’s roads.

In the late 1970s the Canadian trucking monthly, Motor Truck, ran an appeal asking operators and manufacturers who had used the earliest B-Trains. The result was revealing in that many operators who had used B-Trains for only a short time thought that theirs was probably the first. In fact the only real evidence of B-Trains prior to the 1970s was supplied by Arrow Transfer of B.C. who said they first employed the concept in 1967. However, Tank Truck Transport (thought to be from Sudbury, Ontario) claimed to operate a twin tank B-Train built by Fruehauf Canada hauling acid for the International Nickel Company in the mid 1950s, but regrettably could not provide photos or documentary evidence to support this. But at the time this unsubstantiated claim certainly suggested that it was the first known example.

In fact a long way south of Canada in sunny California Dan Keeney had unknowingly beaten everyone to the punch. Dan had started out on his truck-driving career back in 1933. But following an accident in 1936, he went to work for International Harvester as a truck salesman, a task he carried out with great success for the following eight years. But the call of the open road was ever present and in 1944 he could resist the temptation no longer and left IH in order to start up his own company, Keeney Truck Lines. By 1947 he had gone on to design and build his own twin-trailer combination by fitting a fifth wheel at the back of the first trailer. In this way he built and later operated what would seem to be the earliest example of a B-Train recorded anywhere.

Keeney B-Train International Photos

The first Dan Keeney B-Train was hauled by a gas-powered International K-11 single screw tractor capable of legally grossing 77,000-lbs (35-tonnes). The lead trailer was about 20-feet long including the tail section and the second about 30-feet long. This is interesting because most subsequent B-Trains operated 30 or even 40-years later were made up of trailers of equal size! Deck space was important to Dan Keeney and by using his B-Train he realized a massive increase of 30% over a standard 35-foot long semi-trailer.

By 1953 six similar B-Trains were in use, these having been built by the now defunct Foster Trailer Company of Los Angeles. The combinations were only ever used in California and it was almost 40-years later that Dan’s son, Walt Keeney, reintroduced B-trains to the Keeney operation. The first of these was used for hauling flour and was operated throughout Washington State. During the mid 1990s, it was my great privilege to meet Dan Kenney and his son, Walt at the Morton, WA. Loggers’ Jamboree and later to film a Keeney B-train tanker combination hauled by a conventional Freightliner.

Walt Keeney Freightliner COE plus tanks

Very few B-Trains seem to have been used anywhere in North America during the 1950s and 1960s although no doubt a few isolated examples were tried by enterprising and innovative operators. But in the 1970s, there was a resurgence of interest in the concept as manufacturers and truck operators sought new ways in which to improve their efficiencies and to reduce accidents. A-Trains, which were in common use at the time, were not known as “wiggle wagons” for nothing and the B-Train provided a viable alternative in some operations.

British Columbia, Canada’s most Westerly province, witnessed the introduction of several interesting examples during this period and trailer sets ranged from flat decks to tanks and even included dual-purpose ‘platypus’ trailers which covered both modes of transport. In the East too transport companies in Ontario and Quebec were cautiously introducing B-Trains to their fleets of tankers and flat decks.

BC Outfits
Labatt’s Freightliner KW W-900 with load of lumber
Fern Cote Freightliner Powerliner Dave Chambers Trucking Mack Ultraliner and set Chip Vans

It is a moot point as to whether a trucker engaged in hauling lumber from Ontario saw and copied the 1970s B-Train configuration from a Michigan-based steel hauler, or whether it was the other way around. If anyone is certain they have the definitive answer to this, please let me know! Of course it is always possible that the two systems evolved independently, but at the same pace, in what is known as ‘parallel development’ but that seems unlikely. What is certain is that from about 1975 onwards, Michigan’s steel haulers started to abandon their A-Trains in favour of B-Trains while Canada’s lumber haulers followed the same route.

The Michigan rigs of the period were certainly extremely visually appealing, the biggest rolling on 11-axles in total, grossing up to 160,000-lbs (72.2-tonnes) and rolling behind exotic breeds such as Brockway, Diamond-Reo, Hendrickson and Peterbilt, even the latter marque being virtually unknown in Eastern Canada at the time. But Canada’s seven and eight axle combinations were not far behind with the biggest grossing 140,000-lbs or 63.5-tonnes. What is still unclear is why Canada and Canadian truckers have adopted the B-Train for almost every type of load whereas in the USA, the concept seems limited almost exclusively to Michigan State.

Michigan Peterbilt 352 cabover steel-hauling outfits

At a time when Canada’s Provincial Trucking Associations were still negotiating for some sort of legislative harmony, British Columbia was already unwittingly setting standards for others to follow. In order that the new B-Trains should not impede traffic flow, a minimum horsepower-per-tonne rating was introduced. At the same time, a self-steering axle on the second trailer became a legal requirement (though quite how this improved handling remains a mystery) and a ‘first kingpin to rear of rearmost trailer’ maximum dimension was stipulated. The Western B-trains were one metre longer than those used in the Eastern provinces and these impressive 23-metre combinations were soon to be found snaking through B.C.’s urban areas or powering across the challenging Rocky Mountains.

Freightliner conventional Freightliner COE at Scales Freightliner conventional by piles of wood chips

As acceptance by authorities, operators and drivers increased, so the applications in which B-Trains could be used expanded. However, this did not mean that they suited every job. For example boxvan trailers were nearly always hooked up via a dolly converter in A-Train configuration because it was usually necessary for them to be backed up against loading bays. This was impossible with the lead trailer in a B-Train set because the tail section was in the way. So trailer manufacturers quickly developed a mechanism that allowed the tail section to be retracted under the floor for loading and unloading and this system inevitably became known as the ‘goodbye dolly’. But such systems are, by necessity, both complex and costly. The principle of the B-Train has, however, maintained its popularity with tank operators, steel and lumber haulers – for reasons of stability – with mid-Western grain haulers and wood-residual haulers everywhere who like to utilize every last cubic centimetre of capacity!

Home Hardware Sliding Bogie Vans.

The wood residuals business is an important part of Canada’s economy and truck operators engaged in hauling these products use some of the most sophisticated B-Trains to be found anywhere. For more than a decade operators such as Trimac, Arrow Transportation and Dave Chambers Trucking have operated high-volume B-Train sets which not only handle safely in the mountains but which squeeze every gram of payload aboard. A special feature of these combinations is that when unloading the two trailers form a single unit which allows the second to tip its load through the first. It’s a slick system and light years ahead of A-Train systems used in Washington State where each trailer is unloaded separately. Needless to say, chip haulers in Washington State look Northwards to Canada with a degree of professional jealousy as they watch Canadian operators haul higher weights in more stable twin-trailer combinations that can be unloaded in one hit!

Gold Star Trucking Mack and bulk chip vans from Peace River Maritime Provinces Volvo VN-660 and Chip Vans.

South Africa Interlinks
More photos added
September 13, 2008
New Zealand B-Trains
More photos added
September 13, 2008
Australia B-Doubles
More photos added
September 13, 2008
Sweden's B-Trains
More photos added
February 7, 2009
The Netherlands B-Trains
More photos added
September 13, 2008
France B-Trains Michigan Trailer Combinations Brazil B-Trains Mexico Canada


In terms of development, it would appear that there is really very little scope left where the B-Train configuration is concerned. As will be seen from the above, the idea has been adopted by countries as far afield as Sweden in Northern Europe and New Zealand in the South Pacific and by operators hauling anything from asbestos to zinc. So in terms of finding new applications for B-Trains, this seems unlikely. Similarly, the concept is now widely accepted by drivers, many of whom say they prefer hauling a B-train to a single semi trailer because of the feeling of increased stability. Australian designers appear to have taken the idea to its practical limits in terms of size and weights so perhaps the only way the B-Train will develop is in the areas or countries where it has yet to be widely accepted. It is already evident that with the exception of Michigan and Washington states, there appears to be very little take-up of the idea in the U.S.A. so there is enormous potential there. And there are other countries such as Argentina and Chile in South America where the idea could easily find acceptance.

However, it is encouraging to see that development is on-going, albeit the changes reflect refinement of an existing idea rather than radical new concepts. For example, research into the transport of long logs has been carried out by the Forest Engineering Research Institute of Canada (FERIC) using a tri-drive tractor and a special B-Train with a sliding pin mechanism on the second trailer. Such ideas demonstrate the will to further exploit the uses of B-Trains. Dan Keeney. What have you started?

Thanks to Mike Beesley, Pete Connock, Ford Motor Company (Australia) Freightliner (Australia) Arthur Ingram, Walt Keeney, Kenworth Trucks (Australia) Keith Robertson and Richard Tew for the use of their illustrations where necessary. Thanks also to Charles Wilson of Modern Bulk Transporter magazine for information on the markets in Brazil and Mexico. Thanks also to Alan Drake, who kindly supplied the images of the French B-Trains.


If anyone visiting this site has information which supports or contradicts this information or can help in any way with additional material, please contact Hank Suderman. Thank you.