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About "Standard steam locomotives"
The website is designed to give a rapidly accessible summary of the basic specification data of various steam locomotives worldwide, on gauges from 15 inches to seven foot (and a monorail). Since it is not feasible to give a comprehensive coverage of all types, the emphasis is on "standard" steam locomotives, those types that were built in the largest quantities, or that shared major components (such as boilers) with standard types. Locomotives of especial interest are often included as well. The choice is limited by the availability of reliable data. New railways are gradually being added, and earlier tables improved.
1. What is in the tables?
The table columns, in order, give the following data:
2. What isn't in the tables?
Fitting one class per line means that there is only room for the primary, basic data. It is not possible to list secondary data such as tractive effort, maximum speed, horsepower, etc. However, some quick rules of thumb can provide estimates of these derived quantities in terms of the table entries:
3. How can you compare data from different tables?
Clicking on the "open second copy" field of the index page should open the index page in a second browser window. Tables may then be selected from each index page, and the two windows arranged one above the other.
4. What was the source of the data?
The information has been collated from diagram books, manufacturer's catalogues, published books, and journals such as "Railway Age," "Engineering," etc. I would also like to acknowledge contributions from Ab Baird, Larry Baxter, Reg Carter (1934 - 2007), S. Damus, A.E. "Dusty" Durrant (1929 - 1999), Robin Gibbons, Dr Malcolm Hardy-Randall, Barry Heath, Hugh C. Hughes (191? - 1998), Ian Hughes, Berne Ketchum, Ichiro Kondo, Steve Llanso, Joe Lloyd, Stephen Low, Mark Lundquist, Bruce Maxwell, Gerry Nichols, Kurt Niederer, R. Ramaer, N.D.H. Smith (1926 - 2003), Wolfgang Staiger, Allen Stanley, Jim Todd, Ralph Wallio, Malcolm Wilton-Jones, and Jiří Woitsch, as well as the B&O Museum (Baltimore, MD), Colorado Railroad Museum (Golden, CO), James H. Andrew Railroad Museum (Boone, IA), Museum of Science and Industry (Manchester), and Muzeum Kolejnictwa (Warsaw). If you are able to fill any of the gaps in the tables, please visit the Post Office.
5. How reliable are the data?
Except for cylinder stroke, all the other measurements listed are subject to variation of as much as several percent. Boiler pressures depend on the setting of the safety valves, and with pop valves there is a difference of several pounds per square inch between the opening and closing pressures. Cylinders and driving wheel tyres are subject to wear and repair, altering the diameter. Since the weights listed are those "in working order," there may be variation of up to several tons depending on how high the water is being carried in the boiler, or how much the water and fuel supplies of tank engines have been depleted. Adjustments to the suspension may trade off between the adhesive and non-adhesive weights. The heating surfaces may have been calculated on the Anglo-Saxon "steam side" system or the continental "smoke side" system. (The former system overstates the evaporative surface and understates the superheating surface by up to 25% relative to the latter.) Whichever system is used, the surfaces also vary as the boiler is brought up to working pressure. Within large classes, there may be substantial variation between different members. If a locomotive is in service for a long period of time, its specifications may change as a result of reboilering or other factors. Taking all these effects into account, there are often still discrepancies amongst different sources. Finally, the operation of data entry is not completely reliable, although such errors may gradually be identified and eliminated as the tables are used.
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