The Union Pacific 9000 class was the only class of steam locomotives with a 4-12-2 wheel arrangement ever to be built. Under the Whyte notation for the classification of steam locomotives, the locomotives had four leading wheels, twelve coupled driving wheels, and two trailing wheels. As the Union Pacific was the only operator of this wheel arrangement, it was often nicknamed the Union Pacific type.
Front view of the same locomotive. The third cylinder and the mechanism that controls it can be seen below the smokebox.
These locomotives were used to increase the speed of freight trains in flat country, and were fairly successful, but had very high maintenance requirements, largely because of their use of an inside third cylinder driving the cranked second driving axle between the frames. There was no inside valve gear, however. ALCO had obtained permission to use the conjugated valve gear invented in the UK by Sir Nigel Gresley, who was the chief mechanical engineer of the London and North Eastern Railway. This system used two hinged levers connected to the outer cylinder's valves to operate the inner cylinder's valve. The 9000 class locomotives were the largest to use Gresley gears.
Between 1934 and 1940, eight of the first fifteen locomotives had their Gresley gear removed and were converted to a "double Walschaerts" valve gear, which utilized a double eccentric (return) crank and second link on the right side (similar to the gear Baldwin used on its three-cylinder experimental compound 4-10-2 No. 60000), which operated the valve for the inside cylinder. Union Pacific referred to this system as the "third link". The 4-12-2s constructed from 1928 utilized roller bearings in the Gresley lever bearings, thus none of these engines were converted. The pre-1928 engines not converted received the roller bearing levers in 1940, and no further conversions were made.
During design, the third and fourth driving axles were planned to be "blind" (flangeless) in order to improve curve handling, but ALCO's lateral motion devices on the first and sixth axles (which allowed the axles to slide up to two inches to the side) made this unnecessary. They had the longest rigid wheelbase in North America, and the longest in the world until the Soviet Union built their AA20 4-14-4 locomotive in 1934. The trailing truck carried the same axle load as the drivers, which was unusual.
There has been debate as to whether the first driving axle of the 4-12-2 was cranked to provide clearance for the main rod connected to the second axle. Union Pacific drawings show no such crank on the first axle. Based on the published dimensions, at its closest, the centerline of the inside rod was 11.645 in (29.58 cm) from the centerline of the first axle. (UP drawings reproduced in Kratville and Bush's Union Pacific Type books show the inside rod 113 in (290 cm) long and the first and second driver axles 88 in (220 cm) apart. The inside cylinder axis was inclined 9.5 degrees and was 32 in (81 cm) above the plane of the driving axles at a point 181 in (460 cm) ahead of the second driving axle, so the cylinder axis missed the centerline of the second axle by 1-11/16 inches. The rod centerline is closest to the axle when the crank is 54.49 degrees below horizontal.)
Only one example has survived into preservation. Union Pacific 9000, the prototype of the class, is preserved at the Railway and Locomotive Historical Society's museum at the Los Angeles County Fairplex in Pomona, California. It received new boiler paint in 2006-2007.
References
Drury, George H. (1993), Guide to North American Steam Locomotives, Waukesha, Wisconsin: Kalmbach Publishing Company, pp. 397–398, 404, ISBN0-89024-206-2, LCCN 93041472
Hollingsworth, Brian (2000). The Illustrated Dictionary of Trains of the World. London: Salamander Books Ltd. ISBN1-84065-177-6.
Kratville, William W.; Bush, John E. (1990). The Union Pacific Type, Vol. 1. Omaha, Nebraska: Barnhart Press. LCCN 90082171.
Kratville, William W.; Bush, John E. (1995). The Union Pacific Type, Vol. 2. Omaha, Nebraska: Barnhart Press. LCCN 90082171.
Westcott, Linn H. (1960). Model Railroader Cyclopedia - Volume 1: Steam Locomotives. Kalmbach Books. ISBN0-89024-001-9.
February 24, 2023
union, pacific, 9000, class, this, article, multiple, issues, please, help, improve, discuss, these, issues, talk, page, learn, when, remove, these, template, messages, this, article, includes, list, references, related, reading, external, links, sources, rema. This article has multiple issues Please help improve it or discuss these issues on the talk page Learn how and when to remove these template messages This article includes a list of references related reading or external links but its sources remain unclear because it lacks inline citations Please help to improve this article by introducing more precise citations September 2011 Learn how and when to remove this template message This article contains weasel words vague phrasing that often accompanies biased or unverifiable information Such statements should be clarified or removed September 2011 Learn how and when to remove this template message The Union Pacific Railroad 9000 Class was a class of 88 steam locomotives built by ALCO for the Union Pacific between 1926 and 1930 Union Pacific 9000 seriesThe prototype UP 9000 as preserved at the Los Angeles County Fairplex in Pomona California Type and originPower typeSteamBuilderAmerican Locomotive CompanyBuild date1926 1930Total produced88SpecificationsConfiguration Whyte4 12 2 UIC2 F1 h3Gauge4 ft 8 1 2 in 1 435 mm Driver dia 67 in 1 702 mm WheelbaseLoco amp tender 91 50 ft 27 89 m Length102 ft 7 in 31 27 m Axle load59 000 lb 26 762 kg 27 t Adhesive weight354 000 lb 160 572 kg 161 t Loco weight496 500 lb 225 209 kg 225 t Tender weight310 599 lb 140 885 kg 141 t Total weight807 099 lb 366 094 kg 366 t Fuel typeCoalFuel capacity42 000 lb 19 051 kg 19 t Water cap 18 000 US gallons 68 000 l 15 000 imp gal Firebox Firegrate area108 25 sq ft 10 057 m2 Boiler92 in 2 337 mm Boiler pressure220 lbf in2 1 52 MPa Heating surface Firebox591 sq ft 54 9 m2 Superheater Heating area2 560 sq ft 238 m2 CylindersThreeCylinder sizeOutside 2 27 in 32 in 686 mm 813 mm Inside 1 27 in 31 in 686 mm 787 mm Valve gearWalschaertsPerformance figuresMaximum speed50 mph 80 km h Tractive effort96 646 lbf 429 9 kN Factor of adh 3 66CareerOperatorsUnion Pacific RailroadClassUP 1 through UP 5Numbers9000 9087Retired1953 1956PreservedOne preserved No 9000 remainder scrappedDispositionNo 9000 on static display at the RailGiants Train MuseumWheel arrangement EditThe Union Pacific 9000 class was the only class of steam locomotives with a 4 12 2 wheel arrangement ever to be built Under the Whyte notation for the classification of steam locomotives the locomotives had four leading wheels twelve coupled driving wheels and two trailing wheels As the Union Pacific was the only operator of this wheel arrangement it was often nicknamed the Union Pacific type Other equivalent classifications are AAR wheel arrangement 2 F 1UIC classification 2 F1 also known as German classification and Italian classification French classification 261Turkish classification 69Swiss classification 6 9History Edit Front view of the same locomotive The third cylinder and the mechanism that controls it can be seen below the smokebox These locomotives were used to increase the speed of freight trains in flat country and were fairly successful but had very high maintenance requirements largely because of their use of an inside third cylinder driving the cranked second driving axle between the frames There was no inside valve gear however ALCO had obtained permission to use the conjugated valve gear invented in the UK by Sir Nigel Gresley who was the chief mechanical engineer of the London and North Eastern Railway This system used two hinged levers connected to the outer cylinder s valves to operate the inner cylinder s valve The 9000 class locomotives were the largest to use Gresley gears Between 1934 and 1940 eight of the first fifteen locomotives had their Gresley gear removed and were converted to a double Walschaerts valve gear which utilized a double eccentric return crank and second link on the right side similar to the gear Baldwin used on its three cylinder experimental compound 4 10 2 No 60000 which operated the valve for the inside cylinder Union Pacific referred to this system as the third link The 4 12 2s constructed from 1928 utilized roller bearings in the Gresley lever bearings thus none of these engines were converted The pre 1928 engines not converted received the roller bearing levers in 1940 and no further conversions were made During design the third and fourth driving axles were planned to be blind flangeless in order to improve curve handling but ALCO s lateral motion devices on the first and sixth axles which allowed the axles to slide up to two inches to the side made this unnecessary They had the longest rigid wheelbase in North America and the longest in the world until the Soviet Union built their AA20 4 14 4 locomotive in 1934 The trailing truck carried the same axle load as the drivers which was unusual There has been debate as to whether the first driving axle of the 4 12 2 was cranked to provide clearance for the main rod connected to the second axle Union Pacific drawings show no such crank on the first axle Based on the published dimensions at its closest the centerline of the inside rod was 11 645 in 29 58 cm from the centerline of the first axle UP drawings reproduced in Kratville and Bush s Union Pacific Type books show the inside rod 113 in 290 cm long and the first and second driver axles 88 in 220 cm apart The inside cylinder axis was inclined 9 5 degrees and was 32 in 81 cm above the plane of the driving axles at a point 181 in 460 cm ahead of the second driving axle so the cylinder axis missed the centerline of the second axle by 1 11 16 inches The rod centerline is closest to the axle when the crank is 54 49 degrees below horizontal Union Pacific UP classes Year Quantity Class Alco order number Alco serial numbers Union Pacific Number Notes1926 1 UP 1 B 1684 66544 Union Pacific 9000 Preserved1926 14 UP 2 B 1684 67024 67037 Union Pacific 9001 9014 9004 to OWR amp N 9708 then back to UP 90041928 15 UP 3 B 1706 67581 67595 Union Pacific 9015 90291928 8 UP 3 B 1708 67596 67603 Oregon Washington Railroad and Navigation Company 9700 9707 to Union Pacific 9055 90621929 25 UP 4 S 1646 67944 67986 Union Pacific 9030 90541930 15 UP 5 S 1701 68490 68504 Union Pacific 9063 9077 to Oregon Short Line 9500 95141930 10 UP 5 S 1701 68505 68514 Union Pacific 9078 9087Total 88Only one example has survived into preservation Union Pacific 9000 the prototype of the class is preserved at the Railway and Locomotive Historical Society s museum at the Los Angeles County Fairplex in Pomona California It received new boiler paint in 2006 2007 References EditDrury George H 1993 Guide to North American Steam Locomotives Waukesha Wisconsin Kalmbach Publishing Company pp 397 398 404 ISBN 0 89024 206 2 LCCN 93041472 Hollingsworth Brian 2000 The Illustrated Dictionary of Trains of the World London Salamander Books Ltd ISBN 1 84065 177 6 Kratville William W Bush John E 1990 The Union Pacific Type Vol 1 Omaha Nebraska Barnhart Press LCCN 90082171 Kratville William W Bush John E 1995 The Union Pacific Type Vol 2 Omaha Nebraska Barnhart Press LCCN 90082171 Westcott Linn H 1960 Model Railroader Cyclopedia Volume 1 Steam Locomotives Kalmbach Books ISBN 0 89024 001 9 Retrieved from https en wikipedia org w index php title Union Pacific 9000 Class amp oldid 1130203595, wikipedia, wiki, book, books, library,
