by Chock » Tue Aug 16, 2011 5:19 pm
Initially North American locos were pretty much all from the UK (i.e. in about 1830-ish), so the early ones inherited the British system of buffers and chains and the use of that system (in varying forms) was pretty common. In fact, you can see how much influence the British system had in one of the very first steam locos operated in the United States, which is the oldest still-functioning steam loco in the world (now at the Smithsonian Institute), that loco being the 'John Bull' - actually more properly called the 'Stevens' after the president of the US railroad company that bought it - but despite its official 'Stevens' name, it was almost universally referred to as 'the Old John Bull' because of its British origins. Interestingly, the John Bull ended up being heavily modified into what would come to be seen as the classic US loco type, in that it was originally an 0-4-0 loco, but the tracks it had to run on were poor quality cast iron, so it had smaller leading wheels added to keep it on the track, which worked well and pretty much became the prototype for the wheel configuration seen on what most people would regard as a classic old timer US 'wild west' locomotive. This is a bit like the North American P-51 Mustang with the Rolls Royce Merlin engine, where a combination of the best of British and American engineering and ingenuity combined to make an ideal solution.
Back on the original topic however, the trouble with buffers and chains is that they are better suited to curved tracks than long straight ones, where a non-rigid hook and chain coupling device exhibits less stress owing to the fact that things can move around a bit more (hence the need for buffers). But a large number of early US railroads were more about long distances and straight lines across vast open plains than the circuitous affairs found in Britain, and it was found that rigid couplers of the Janney (knuckle) type were better suited to the US (they can pull more weight too generally speaking, which is another plus point for the generally longer and heavier US trains), so that system was adopted in the US. In fact the system was forced on US train operators by the Government via the Safety Appliance Act of 1893, where a number of rulings intended to reduce casualties on US railroads (particularly in switching operations) included the mandatory use of automatic coupling devices that did not need someone to go in between wagons to manually couple them up. The legacy of that act can actually still be seen in US trains today in the widespread use of automatic knuckle couplers and the fact that almost all North American locomotives have some means of allowing a crew member to ride on the ends of freight cars and locos with the additions of end 'porches' with grab rails, since that too was a ruling included in the Safety Appliance Act. But up until that act became mandatory law (in 1900, since there was a seven year grace period to allow railroad companies to conform to the rules), there were plenty of different coupling systems in use in the US, including buffers and chains, drop pins etc.
Ironically, we're now seeing most European countries (including Britain) adopt the US rigid automatic coupling system, and its only taken us Brits about a hundred years to suss out that the US-style rigid automatic coupling system is better!
Al