Locomotives with asymmetrical wheel arrangements in general were not unknown, and examples that come to mind are C-B (diesel and electric), B-A1A (diesel), 2-D-1 (diesel and electric), 2-C-1 (electric) and 2-C+C-1 (electric). Some of these have already been mentioned here on the basis that as well as asymmetry, they have another or other very unusual features.
All of the above may be characterized by the fact that they have one fewer axle at one end as compared with the other.
Against that, the following candidate for inclusion here stands out because it has two axles at one end and four at the other end. This I think represents a higher degree of asymmetry than was customary for asymmetrical locomotives. The wheel arrangement could be described as B-B-B, but B-(B-B) might be more accurate. At one end it had a “conventional” B truck. But at the other end it had a pair of similar B trucks, independent of each other, upon which rested a span bolster, with the locomotive body on top of that. Here is a not-very-good picture:
Pictures of this locomotive are scarce, let alone detailed information. However, a line diagram may be found on-line here: https://www.flickr.com/photos/alcoalbe/ ... 310999745/
Apparently 22 were built for RAN (Régie des chemins de fer Abidjan-Niger) Ivory Coast, during 1971-76. The original design and early builds were attributable to French manufacturer CEM, but later builds were done by French manufacturer MTE.
This very odd locomotive is explained by its origins. It was derived from a larger eight-axle B-B-B-B model developed by CEM in 1969 for the French African metre/Cape gauge roads at the specific request of Oferom, the bureau for French overseas (Outre-Mer) railway systems. Oferom wanted 3600 hp with an axle loading no greater than 16 tonnes (roundly 35 000 lb), which meant at least 8 axles. It also wanted short wheelbase B trucks able to negotiate 50-metre radius curves (I make that about 35 degrees in the American system). Thus CEM chose a four-truck B-B-B-B wheel arrangement with two trucks at each end bridged by a span-bolster. It was referred to as both a BB-BB and as a 4B type.
With the BB-BB type in place, CEM went on to derive smaller versions using respectively three and two of the B trucks. In the three-truck case, evidently using a single truck at one end and a pair with span-bolster at the other end was better from a component standardization viewpoint than would have been a conventional B-B-B arrangement in which the centre truck would have required provision for significant lateral movement. In keeping with French practice of the time, the trucks were of the monomoteur type, that is one large traction motor driving both axles. An interesting aspect is that whilst the single-truck installation had its own set of swing links to provide and control lateral motion, when paired under a span bolster they did not have individual swing links, but rather the span bolster itself was connected to the frame by swing links. In contrast, American practice, as in the GE GTEL4500 and U50, was for each truck to have its own lateral motion mechanism, with the span-bolster connected to the frame by a simple pivot.
Information of this locomotive series as a whole, from a later OEM brochure, may be found at the same site as noted above. Go to: https://www.flickr.com/photos/alcoalbe/ ... 310999745/
for the front cover and then scroll leftwards.
You do not have the required permissions to view the files attached to this post.