Author Topic: What are A and B trains? whats the difference between an "A-train" and "B-Tain?"  (Read 2904 times)

CaptainRay

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Im curious to know what A- trains and B- trains are, and whats the difference between them. From what i've read one is Canada and the other is American, but i'm not sure. I see you guys talk about them alot in foodservice threads like Sysco, and U.S. Foods, so i'd like to know about them. Thanks guys ;-)

Paccar 105

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A and/or B trains have nothing to do with nationality.It has all to do with how the setup is.

A train:         tractor+semi trailor+dolly+semi trailor

B train:          tractor+semi trailer with a fith wheel+semi trailor
Quote

Picture from the Biglorryblog

fangio

Running Pete

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Well said, an A train is usually a 40-48 foot flat with a long tounge dolly and a 28-30 foot flat. A btrain is usually a 32 or around there foot lead and a 28 to 30 foot following.
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doug mckenzie

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Lengths are not that important, except in situations to meet overall combination lengths.

So .....

An A train has a convertor dolley used to connect the first trailer to the second trailer.
These are extensively used by most U.S. LTL carriers - they enjoy the equipment flexibility offered.
Trailers are often 34 to 28 feet in length, but can also be a combination of a "long box" of 48 feet or so and a following 24/28 foot trailer which is a "Rocky Mountain Double" but still using a converter dolley.

A Btrain can be made of 2 different length trailers, the main difference being that the last trailer, or full trailer to some and "kite" to some of those guys running LTL rides on an extension of the lead trailer which carries it's own fifth wheel.
In the case of B Train vans, the extension is on a sliding bogie that slides under the lead trailer for single trailer use and slides out for B Train use.

Nationality, as mentioned, has nothing to do with type.
Canadian carriers favour the B Train for the simple reason of 1 less pivot point to be concerned about.
U.S. carriers have invested alot of money in A Train technology.

If you go back to Hank's main picture site, Martin Phippard has extensively photographed and written about the development and use of both A and B Trains in world-wide service.
Right-wing Old School.

Son of a Trucker

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Yea, great explinations.

A-Trains have a dolly to connect the trailers, and B-Trains are hooked together via a fifth wheel. There, I gave a simple explination  :-)

ThaddeusW

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Yea, great explinations.

A-Trains have a dolly to connect the trailers, and B-Trains are hooked together via a fifth wheel. There, I gave a simple explination  :-)

Hold up there, the dolly on an A train also has a 5th wheel.

An A train uses a converter dolly to allow a semi trailer to be hitched to another semi trailer using a 5th wheel. The lead trailer is hooked to the tractor via a 5th wheel and has a hitch at the rear (most commonly a pintle hook). The converter dolly is simply a frame with an axle or two (or even three) and 5th wheel that hooks to the lead trailer hitch. The dog trailer hooks to the dolly 5th wheel creating two pivoting points (Hitch and 5th wheel). The A train is the most flexible design but the least stable. A longer trailer and/or longer hitch bar on the converter dolly increases stability.

A B train has two or more trailers directly connected to one another. In a B double (most common) the leading trailer hooks to the tractor via the 5th wheel. The lead trailer also has a 5th wheel mounted directly to it. The dog trailer (second trailer) then hooks directly to the lead trailer. So between the trailers you have only one pivot point. This method is the most stable and maneuverable of the two.

There is also the C train but it is very uncommon. It combines the versatility of the A train with the stability of the B train. It works by having a converter dolly with two hitch bars that stabilize the dolly and keep it strait. This creates one pivot point and removes the need for the lead trailer to have a 5th wheel mounted to it. Some C dolly designs have the hitch arms crossed over and have built in steering to reduce tire scrubbing when turning. I believe they are more common in Mexico
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Running Pete

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Don't forget, some are turn tables that do not disconnect from the trailing trailer on an A train. :wink:
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D50

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CaptainRay

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Thanks so much guys! I have been wondering since i joined what the difference is. Thanks again!

Son of a Trucker

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Hold up there, the dolly on an A train also has a 5th wheel.

Yea, I just figured that was just common sense so I never mentioned it.

A-train's use a dolly, and B trains are hooked right together. I just figured a fifth wheel was obvious as thats what the trailers need to 'connect,' so I didn't mention it.  :-)

Rob Archer

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Wee Willy

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A b train is way easier to back up, that's the biggest difference. :evil:  :-D
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Cornbinder

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A b train is way easier to back up, that's the biggest difference. :evil:  :-D

I pull Double's  for FDX and Ive tried backem up, and it's a real pain in the A_ _ . There's guy's there that do back em up but it take's forever, quicker to just bust the set down.

Wee Willy

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I pull Double's  for FDX and Ive tried backem up, and it's a real pain in the A_ _ . There's guy's there that do back em up but it take's forever, quicker to just bust the set down.
Like they say, if you want to play Carnegie hall, you have to practice practice practice. :lol:

I had difficulty at first, but got lots of practice at a couple jobs I had, (both A's + B's), but after a month of pulling B's steady, I could back them up almost as well as I could a single, even when blind siding.

After pulling a set of B's for a couple years then going back to a straight trailer, I got confused the first few times I backed up, trailer kept going the wrong way, still had two trailers on the brain. :|

It's been awhile, probably get them twisted up pretty bad or back into something if I tried it these days.
:roll: :-D
 
The first rule of the road is:
"If anything can happen, at any time, it will!"