By World War I the 0-4-0 wheel arrangement had largely slipped into the history books, and six- or eight-coupled steam switchers were the norm on most railroads. The self-proclaimed Standard Railroad of the World, however - stubbornly independent and known for its home-grown motive power - in 1916 began building perhaps the most modern 0-4-0's ever constructed. Built in the Pennsylvania Railroad's Juniata shops, the A5s was, in Al Staufer's words, "a junior edition of mammoth road power," with modern appliances and machinery details never before seen on an 0-4-0. The "s" in the engine's name stood for "superheater;" other modern features included Walschaert valve gear and power reverse. The large vertical tanks under the cab were air brake reservoirs. A sloping rear tender deck allowed better visibility for backup moves, and the locomotive of course had the Pennsy's characteristic Belpaire firebox.
The diminutive 0-4-0's were right at home in the narrow streets and tight corners of industrial and wharf areas, particularly in Philadelphia, New York, and Baltimore. Because they worked at slow speeds among tightly-spaced buildings, many A5's carried a fire hose in a metal box to enable them to help out in an emergency. Some were also used as yard goats to move dead engines in roundhouse areas. The Pennsylvania refurbished A5s No. 94 for its historical locomotive collection, and that switcher - or "shifter" in Pennsy parlance - resides today in the Railroad Museum of Pennsylvania in Strasburg, PA.
The A5s returns to the Premier line in 2007 accompanied by a new, non-Pennsy version; a standard radial firebox on the new version replaces the squared-off Pennsy Belpaire firebox on the A5s. Thanks to Proto-Sound 2.0, our super-detailed 0-4-0s offer all the features you'd want in a steam switcher: smooth, steady operation down to 3 scale miles per hour, remote Proto-Couplers front and rear, chuffing sounds and puffing smoke synchronized with the drivers at a correct four chuffs per revolution, adjustable smoke intensity, great pulling power, directional lighting, and authentic sounds.