2 ms·

Or use seven axle locomotives. (Did a bit of research, at least one has existed: http://cs.trains.com/trn/f/111/t/72627.aspx http://cs.trains.com/trn/f/111/t/7

• jcranmer 6y ago
  Broadly speaking, with electric drive, it generally makes the most sense to have both your four and aft bogies as all-drive axles, and there's no real compelling reason to have those axles be different. In practice, this means that the vast, vast majority of modern locomotives are B-B or C-C (2-axle/3-axle bogies, respectively), with B-B-B (3 2-axle bogies) probably the next most common. Other configurations are almost entirely experimental or one-off locomotive configurations. In the steam era, things were rather different. Steam power requires a linkage of rather large drive wheels, which generally means you need unpowered leading and trailing wheelsets for stability and performance purposes. The trailing wheels are almost purely to support the weight on the back end of the locomotive, but leading wheels also help with curves in addition to supporting weight on the front end. Single leading axles were quite common in the steam era, with 2-8-0 being perhaps the single most common arrangement.