Vauclain compound
[1] In practice uneven forces at the crosshead produced excess wear, with increased maintenance costs thus offsetting any fuel economies.
One extra appliance required was a starting valve, manually controlled, which allowed admission of high-pressure boiler steam directly to the low-pressure intake.
[7] It also avoided subjecting the locomotive frame to unequal forces from separate high- and low-pressure sides.
Indeed, at first glance from the side the Vauclain compound can be mistaken for a conventional simple locomotive; the only giveaways are the unusual arrangement of the crosshead and (viewed from the front) the extra cylinder.
The scheme did not produce a more powerful locomotive; the maximum practical tractive force was governed by the weight on the drivers, and this did not change.
[9] In practice lesser results were generally achieved, with Baldwin in 1900 reporting trials by various railroads showing fuel savings of 17% to 45%.
It is the most marked departure from the usual construction of engines, that has elicited general satisfaction wherever introduced, and in view of the reliable and satisfactory performance in service under the largest variations of conditions, immunity from total disablement, ready adaptability within limits of space incapable of accommodating other compound engines, and general applicability to and utility in railway service, it is, in the opinion of your committee, deserving of recognition by the award of the Elliott Cresson Medal of the Franklin Institute, which they hereby recommend.
Significant maintenance difficulties appeared, particularly with uneven forces wearing the crosshead guides.
[14] The two cylinders were supposed to be proportioned so as to do equal work (with the low pressure being three times larger than the high).
[15] All of the compounding machinery was contained in the valve chest, which in American locomotives (in the days before one piece cast frames) was integral with the smokebox saddle.
[16] Two of the four surviving Manitou and Pike's Peak Railway locomotives were converted to compounding after experience with M&PP No.
[17] (Vauclain himself had travelled to the line to deal with operational issues with the original engines in their pre-compounding state.)
[2][17] The Vauclain system was used in Europe, and a Danish example (DSB 996) is preserved at Railworld, Peterborough, England.
[18] 88 Baldwin-built locomotives, from 1912 designated as V class (for Vauclain, В in Russian), were used in Russia from 1896 until the 1920s on several railroads.
