I suppose this could go in several topics on the Forum: the company has gone, the factory is still there, the products were made in Sheffield and the products were largely for transportation purposes.
The Yorkshire Engine Company was founded in 1865 and closed in 1965, having built over 1100 steam, diesel and battery-electric locomotives as well as repairing and building locomotive boilers, mining haulage engines and even, in the early years of the 20th century, motor car manufacture.
The company built largely to order, so many different types of locomotive were built over the years, both for the home market and overseas. As UK main line railways grew larger through amalgamation and set up their own locomotive works, the export and industrial market became more important for YEC. One notable exception to this was the building of 20 Pannier tanks for the Great Western Railway and British Rail (Western Region) in the late 1940s.
Typical of the order book in the early days is that of the first five years' production, which included:
13 locos for the Great Northern Railway, 10 for the Midland Railway, 30 for the East Indian Railway, over 40 for Russia, 2 for Jamaica, 3 for Argentina and several for various mining and industrial concerns.
I was going to write a potted history of the Yorkshire Engine Company, but find that there is a good summary on the Wortley Top Forge site.
The third page of this history appears to be missing, unfortunately. I assume it deals with the YEC's most successful diesel locomotive, the Janus. 102 of these were built, the majority being for the steel industry, and although the last was built in 1965 there are still some at work, including some at Stocksbridge Works and one at EMR in Attercliffe.
A Janus at work at Appleby Frodingham in 2008
There are still around 80 YEC locomotives in existence, although some of the Corus locos are waiting to be disposed of as steel making in this country diminishes further. In addition to the working examples and many on preserved railways in Britain, there are two preserved steam locos in Paraguay, 2 in New Zealand and one diesel in the Madrid Railway Museum.
An aerial view of the factory, presumably at about the time the company closed it's doors. It is the long building in front of the two gasometers.
A couple of photos of the factory in December 2009:
The path alongside is part of the Trans-Pennine Trail, and used to be part of the Great Central Railway's network. It was used (unofficially, at first) by the company for testing newly built locomotives.