Union Pacific Big Boy

The class of 4000 Union Pacific Railroad (UP ), known as Big Boy was the largest and most powerful steam locomotive class of UP and one of the largest and most powerful in the world.

A total of 25 specimens of the type of the American Locomotive Company ( ALCO) were built, 20 in 1941 and five in 1944. The machine was designed by a team led by Otto Jabelmann, under his responsibility also already nevertheless still parallel to the Big Boy built ancestor class was created 3900 ( Manufacturer's designation Challenger with the wheel arrangement ( 2'C ) C2 '). From an unknown employee of the ALCO works the name of Big Boy comes ( big boy ), which he wrote with chalk on the smoke chamber. The term became common to speed quickly for the locomotives of the 4000 class.

Design and technology

The locomotives were designed by the Union Pacific Railroad specifically for use on freight trains in the Rocky Mountains, to avoid the labor-intensive use of prestressing and Nachschiebelokomotiven on the uphill stretches across the Continental Divide. The hardest section on the transcontinental route of the Union Pacific was in fact an elongated slope over the Sherman Hill ( Albany County ( Wyoming) ) south of Ames Monument with a max. Slope of 1.55%. The new locomotives should trains with 3,600 short ton bring (about 3,300 t) without any help on this slope, but also be fast enough so that the entire route between Cheyenne ( Wyoming) and Ogden (Utah ) could be driven without changing locomotives.

From the performance data required for a joint locomotive with the wheel arrangement ( 2'd ) D2 '(: 4-8-8-4 Whyte notation) showed. No other locomotive ever built with this wheel. The Big Boys were - like many of the newer U.S. joint Locomotives - no Mallet locomotives in the strict sense, because there were no compound locomotives. In American, this design is therefore referred to as a simple articulated (single joint).

For firing with low-quality coal the firebox was designed to be very large with almost 14 m² grate area. The locomotives have a mechanical grate feed a Stoker. Coal consumption at full load was up to 25 tons per hour. The locomotive No. 4005 was tentatively converted to oil firing, which is not proven, and therefore scaled back to coal firing.

With a total weight of 548.3 tonnes and a maximum continuous power of 6,290 hp at the hitch ( at 48 km / h) include the Big Boys of the heaviest and most powerful ever built steam locomotives and with a speed of 112 km / h ( 70 mph ) also the fastest articulated steam locomotives. The construction was designed even for 129 km / h in order to offer a high safety margin.

In order to use the Big Boys, had the route between Ogden (Utah ) and Green River ( Wyoming) ( Overland Route ) to be rebuilt in several places. Almost every curve was realigned so that two big boys could meet. Furthermore, the superstructure has been strengthened.

Operational use

The Big Boys met the expectations placed on them fully. In practice, they pulled trains with up to 6,000 tons, and in an attempt on the plane was one of these locomotives even hold a previously inserted with other locomotives 25,000 -ton train alone in transition.

From 1941 to 1957, the locomotives were regularly used in freight transport freight trains, the last of a Big Boy -drawn train ran in 1959. Every one of the 1941 or 1944 -built locomotives put total a distance of more than 1.6 million kilometers. Four locomotives were still operational held until 1962 as a reserve.

For the Big Boys 1941, the 100 -foot turntable (30 m) in the operating stations Ogden (Utah ) ( space still recognizable: 41 ° 31 ' 17 "N, 109 ° 27' 29" W41.52125 - 109.45801805556 ), Green River ( Wyoming) and Laramie (Wyoming) by 135 -foot turntable (41 m) replaced. Often also the hub for yet some of the eastern Cheyenne ( Wyoming) (41 ° 7 ' 48 " N, 104 ° 48' 52" W41.129946944444 - 104.81446805556 ) specified. There, the 100 -foot turntable through a 120 -foot turntable ( 36.6 m) was replaced in 1940, and in 1941 a further 100 -foot slice through a 126 -foot disc ( 38.40 m). For the wheel base of 117 ft 7 in ( 35.83 m) of the Big Boy, this was just enough to turn the locomotive with overhang. This was Exercise appropriate caution because of the risk of accidents for people and serviceable locomotives, and also when stopping the locomotive.

Specimens received

Eight of the 25 built Big Boys are preserved, currently (2013 ) is not in a working condition:

• No. 4004: Holliday Park, Cheyenne ( Wyoming). (41 ° 8 ' 12.3 "N, 104 ° 47' 59.5 " W41.136749 - 104.7998611850 )
• No. 4005: Forney Transportation Museum, Denver
• No 4006: Museum of Transportation, St. Louis (Missouri ) (38 ° 34 ' 19.7 "N, 90 ° 27' 40.3 " W38.572129 - 90.461201150 )
• No. 4012: Steamtown National Historic Site, Scranton ( Pennsylvania) ( 41 ° 24 ' 30.6 "N, 75 ° 40' 18" W41.408496 - 75.671654230 )
• No. 4014: 2013: Los Angeles County Fairplex, Pomona (California ) (34 ° 5 ' 1 "N, 117 ° 46' 13" W34.083571 - 117.770349300 ), re-acquired by the Union Pacific and will continue in Cheyenne (Wyoming are located ) ( see below)
• No. 4017: National Railroad Museum, Green Bay (Wisconsin )
• No. 4018: Age of Steam Railroad Museum, Dallas (32 ° 46 ' 58.3 "N, 96 ° 45' 49.6 " W32.782867 - 96.763787140 )
• No. 4023: Kenefick Park, Omaha (Nebraska ) (41 ° 13 ' 55 "N, 95 ° 55 ' 4" W41.231944444444 - 95.917638888889 )

Intended recommissioning of locomotive No. 4014

The Union Pacific already maintained the Challenger No. 3985 of the predecessor class 3900 as the largest operable steam locomotive in the world and has long been of the opinion that the reprocessing and commissioning of a Big Boy was not worth, since its field of application due to insufficient turning radii of many routes and the large overhang of the locomotive is very limited. The Challenger No. 3985 of the UP Big Boy see a very similar and also have the advantage of oil-firing, while a Big Boy would be to fire with coal.

On 24 July 2013, the UP, however, in a press release announced that they had re-acquired the Big Boy No. 4014 from the Southern California Chapter of the Railway & Locomotive Historical Society in Pomona, California. The machine is to be spent in the workshop of the Union Pacific in Cheyenne and worked there operational until probably 2019. In the workup of an oil-fired furnace is to be retrofitted.

In the fall of 2013 we revised the machine in Pomona extent that it is capable of rolling back. It was moved on a track temporarily misplaced in the parking lot of the County Fairplex and will be shipped to the Union Pacific rail yard in Colton first.

The locomotive No. 4014 was completed in twenty years of operation, approximately 1.65 million kilometers. It was taken out of service in December 1961.

The Big Boy compared

The Big Boy is often regarded as the largest steam locomotive in the world. In fact, however, he was in all the features that can be used for a comparison of dimensions such as length, traction, weight and performance, surpassed in detail each of the other locomotives.

So was the longest steam locomotive with 49 225 mm TE-1 class of Norfolk & Western Railroad, equipped with a steam turbine - generator and electric Einzelachsantrieb in the wheel arrangement ( Co'Co ') ( Co'Co '). Also a similar locomotive of the Chesapeake & Ohio Railway was longer, both types of locomotives also had a higher weight than the Big Boy. The longest steam locomotive piston engine was the S1 ( 42,700 mm).

The Big Boys were designed for a track that was approved for a for U.S. relations rather average axle load of "only" 31 tons. Some other locomotives that were designed with a higher axle load and also for better coal, therefore, could surpass the performance of the UP -Class 4000, including approximately the same weight class H-8 of the Chesapeake & Ohio Railway 7500 hp ( also measured at the hitch measured ) and duplex locomotives of classes S1 and Q2 of the Pennsylvania Railroad, each with about 8000 hp ( on the test bench at Treibradumfang ). In this comparison, the H-8 is the most powerful machine, because at the hitch energy for the proper motion of the nearly 550 -ton locomotive is already deducted.

Also worthy of mention, the class A of the Norfolk & Western with 6300 hp Drawbar tractive effort, which was designed less catchy, but faster than the Big Boy. Among other things, because of good coal was achieved despite significantly lower own weight the same performance. According to A. Haas this was at the hitch even 6450 hp ( at 70 km / h), where the locomotive could haul a heavy fast freight trains with 130 km / h.

As for the tension, the Big Boys were significantly surpassed by the triplex mallets, which each had twelve driving axles into three groups, however, were able to drive only with a very low speed.

Also some modern large steam locomotives exceeded the Big Boys by a few percent to force and friction mass, about which also regarded as very successful classes M3 and M4 of the Duluth, Missabe and Iron Range Railway, which ( in easy terrain ) hauled the heaviest scheduled steam -run trains in the world: a single locomotive moving ore trains 15500-17500 tons at a speed of max. 48 km / h In contrast to these machines, however, were the Big Boys according to overcoming the UP- mountain route usually with 112 km / h on the road, and often even a bit faster because of their good running characteristics. Although an M3 or M4 made ​​6250 hp at the hitch, but would be far too low because of their maximum speed for this almost been unusable Freight service.

Some preferred paths much easier built locomotives with only one engine and two cylinders. Their greatest representative (Texas ) reached 90 % of the Drawbar tractive effort of a Big Boy. However, for this were high permissible axle loads and good fuel requirement, and the machines reached at lower speeds not their great traction. As of mid-tempo but they were hardly the Big Boy after, and the most appealing types covered in flat terrain coal trains of planned 12,000 tons.

Despite the fact that the Big Boys in any discipline were the absolute leader, put them in her size range, the best synthesis of all structural features out its ease of use for driver and stoker was praised what was important for the UP in World War II, since then often only semi-skilled assistants could be used as a heater on these fully loaded trains. Failures on the 60 km long slope, the eye of the congested transcontinental route would have been very cumbersome.

In contrast to the Big Boys were, for example, the weighty triplex mallet or turboelectric structures, which could not meet the expectations set for them.

Swell

• Linn H. Westcott (eds.): Steam Locomotives. Model Railroader Cyclopedia, vol. 1 Second Edition. Milwaukee (USA): Kalmbach, 1981 ( 1960).
• Arnold Haas: steam locomotives in North America. United States and Canada. Franckh, Stuttgart 1978, ISBN 3-440-04493-9.

Film

• Union Pacific Railroad: " Last of the Giants ". Contemporary, produced by the UP film about the series
• SWR: Railroad Romance - Big Boy ( episode 433 of 11 November 2001), including also the aforementioned film " Last of the Giants "