United States of America 4-6-2

a reading & northern railroad 4-6-2 locomotive in 1993

the pacific type first used in united states in 1886. unusual double-cab or mother hubbard type unusually huge firebox, designed use waste tailings anthracite coal mines. while design did not become popular, 4-6-2 rediscovered same reason, improve 4-6-0 ten-wheeler larger firebox.

with altogether 697 pacific locomotives, pennsylvania railroad (prr) largest user of type in united states. railroad bought first experimental k-28 class 4-6-2 alco in 1907. after testing, further 257 pacific locomotives in various versions, designated classes k-2, k-2a, k-2b , k-3, built prr @ altoona works , alco , baldwin between 1910 , 1913.

a pennsylvania railroad k4s

in 1911, prr ordered experimental k-29 class 4-6-2 alco, larger boiler, superheater, mechanical stoker , other innovations. similar k4s class locomotive built prr in 1914, no more built until 1917. between 1917 , 1928, prr built 349 k-4s locomotives , baldwin further 75, bringing total of k4s class 425.

the last prr pacific locomotives 2 large k-5 class locomotives, built in 1929. no. 5698 built @ prr altoona works , had walschaerts valve gear, while no. 5699 built baldwin , had caprotti valve gear. although successful, these locomotives not replicated, since larger 4-8-2 mountain types began introduced. no. 5698 dropped roster in october 1952 , no. 5699 retired in september 1953.

the first modern example of type built duty in united states, built missouri pacific in 1902, chief proponent of type west of mississippi river atchison, topeka , santa fe railway, began buying type next year , owned 274. road have pioneered type, if not belief two-wheeled lead truck sufficient high speed passenger service. began buying 2-6-2 prairie types in quantity baldwin in 1901, 4 cylinder vauclain compound system, weight of 190,000 pounds (86,183 kilograms) , 79 inches (2,007 millimetres) diameter coupled wheels.

when these proved insufficiently stable high speed service, road ordered 1200 class of 4-6-2 pacifics, 2 cylinder simplex engines weighing 220,000 pounds (100,000 kilograms) , fitted 69 inches (1,753 millimetres) diameter coupled wheels on unusually long axle centers. upon arrival on property, drive wheels swapped 79 inches (2,007 millimetres) diameter drivers off earlier prairie types, became fast freight locomotives. these wind in branch line service, successful , outlasted pacifics.

the santa fe ordered additional pacific types of both 4 cylinder balanced compound , 2 cylinder simple types in 7 classes through 1914. these gradually increased 276,500 pounds (125,418 kilograms) , invariably rode on 73 inches (1,854 millimetres) drivers. simple types tended run conservative pressures @ 170 175 pounds per square inch (1,170 1,210 kilopascals), while compounds ran @ 220 175 pounds per square inch (1,520 1,210 kilopascals). examples utilized firebox grate of 54 square feet (5 sq. m), last few classes had larger grates of 57.6 sq. ft. (5.35 sq. m). of these considered light pacifics road, , there few engines of orphan classes well. of these scrapped compounds, rebuilt 2 23½ x 28 (597 x 711 mm) simple cylinders , 220 pounds per square inch (1,500 kilopascals) operating pressure.

the railroad began scrapping these in 1932, , regretted scrapping few during massive traffic of second world war. 2 semi-streamlined brief period during 1939. hauled manner of passenger trains, , saw occasional duty in local freight , helper service. out of service 1955. served on western portion of santa fe system, west of la junta, colorado, line traversed rocky mountains , tackled mountains of california. 4-4-2 atlantic types used on great plains. later, passenger cars grew 85 feet (26m) in length , gained weight due all-steel construction, pacifics replace atlantic types in east , western stretches served new 4-8-2 mountain , 4-8-4 northern types.

these engines not dissimilar usra light pacifics introduced during first world war, differed in respects. santa fe, large united states railroads, accustomed custom-designing own power , refused buy usra designs during ill-fated nationalization of united states railroads under wilson. era, however, did allow many smaller railroads, not afford custom-design power, modernize fleets , saw rise of usra heavy pacific. pennsylvania k-series served prototype these, differed in important aspects such prr s belpaire fireboxes.

the santa fe did not buy usra heavy pacifics, either, after war, baldwin began building new , heavier 3400 class road. these huge @ 288,000 310,350 pounds (130,635 140,772 kilograms), otherwise conservative design 2 simple 25 x 28 cylinders, walschaerts valve gear, 66.8 square feet (6.2 sq m) of grate , 200 pounds per square inch (1,400 kilopascals) boilers. fifty built baldwin through 1924 but, while improvements light pacifics confined simplification , other updates sporadically applied, of 3400s built or retrofitted feedwater heaters , 6 receive 79 inches (2,007 millimetres) diameter driving wheels before or during second world war. got pressure increase 220 pounds per square inch (1,500 kilopascals), 9 received thermic syphons, , little experimentation done combustion chambers , roller bearings. weights reached 312,000 326,000 pounds (141,521 147,871 kilograms). these, too, out of service 1955. 6 santa fe pacific types survive, of them of heavy 3400 class.

alco-built soo line 2719 @ 2 harbors, minnesota, 2009

most of united states railroads offered passenger service, used pacific types. except custom design , sheer volume of units produced, experience of railroads in eastern , western united states not dissimilar of pennsylvania , santa fe, respectively. roads developed these hudson (or baltic) type 4-6-4, others preferred versatility of 4-8-2 mountain , 4-8-4 northern types, , some, santa fe, bought both. 1 railroad, st. louis-san francisco or frisco, converted few existing pacific types hudsons larger fireboxes in springfield shops. pacific type, however, far , away predominant passenger service steam engine in united states until end of steam. lighter streamlined cars led resurgence of light pacific, several railroads applying streamlined shrouds older engines. last pacific built service in united states delivered reading in 1948. or pacifics out of regular service 1960.

one notable 4-6-2, soo line no. 2719 hauled last of soo line railroad’s steam-powered trains in 1959, preserved , restored operating condition excursions. on display @ lake superior railroad museum in duluth, minnesota.