4-12-2

The class of 9000 Union Pacific Railroad (UP ) was a three-cylinder steam locomotive with six driving axles and simple steam expansion. As the only six- coupler world they had an advancing bogie with two axles and run a trailing travois with a barrel. This wheel arrangement is therefore also known as Union Pacific type. The Union Pacific Railroad ordered the built 1926-1930 88 locomotives in the classes UP- 1 to UP -5.

History

The mid-1920s used the Union Pacific Railroad 1'E1' and ( 1'D ) D- locomotives for freight. These machines, however, were only designed for a maximum speed of 32 km / h ( 20 mph ). Therefore, the railway company commissioned ALCo with the development of a fast moving freight train locomotive in order to speed up the traffic on the flat stretches of land. Due to the restrictions imposed by the axle load a locomotive with six coupled in a frame axes has been developed.

The prototype was completed in March 1926 at the ALCo - Brooks plant and received at the Union Pacific the number 9000 and the class name UP -1. Although the design speed was only 56 km / hour, the locomotive had a very smooth run. This facilitated the use velocity between about 72 and 80 km / h

Due to the good results of the prototype further 14 locomotives were built. These were numbered 9001-9014 and the class name UP -2. It was completed in August and September 1926. Further 15 locomotives followed in June / July 1928. Locomotives designated as UP -3 received the numbers 9015-9029. Further eight locomotives of this series was in July / August 1928, the UP subsidiary Oregon - Washington Railroad and navigation ( OWRR & N). These were numbered 9700-9707. In September 1929, the locomotives were delivered to the UP, where they received the numbers 9055-9062.

In the period June - September 1929 a further 25 locomotives were completed in ALCo plant Schenectady. The unclassified as UP -4 locomotives were numbered 9030-9054.

In August 1930 ten locomotives were delivered. These so-called UP -5 locomotives were given road numbers 9078-9087. Further 15 locomotives of this type were in June 1930 to the subsidiary Oregon Short Line Railroad ( OSL) delivered. They were given the numbers 9500-9514.

From September 1928 to September 1929 was the UP 9004 at the OWRR & N under the number 9708 in use.

The series has largely proven, albeit on the basis of the inner third of the steam cylinder maintenance was difficult. Application of the locomotive included the main line of the UP in Nebraska.

The locomotives reached at a speed of 68 km / h and a 48 - % -owned cylinder filling a boiler output of 3665 kW. They moved on a level road trains with 120 wagons with a speed of 80 km / h

The locomotives of the class were decommissioned and scrapped between September 1953 and May 1956.

The only surviving machine of the series, the prototype of the train number 9000 is not operational in the Railway Museum of Railway & Locomotive Historical Society in Pomona, California. The machine was donated to the Historical Society of the UP after decommissioning in 1956. It reached a mileage of 2,704,137 km.

Technical Features

The 17.1 -meter-long tank of 391 -ton locomotive was operated at an acceptable vapor pressure of 15.2 bar, the steam engine made ​​3542 kW and a top speed of with a driving wheel diameter of 67 inches (1.70 m) 97 km / h ( 60 mph ). Due to the large grate area of 10.5 m², the wheels of the last coupled axle stuck partially into the grate. The combustion chamber was 2 meters long. The boiler had a Gaines Wall from Schamottziegel, a fire bridge, which was carried by water pipes, a small tube superheater, and an economizer. The loading of the grate with coal was carried out by Stoker.

The series had two-axle drive. The middle cylinder acted on the cranked second coupled axle, the two outer cylinders, however, on the third coupled axle. Although all three cylinder possessed the same inner diameter, the middle cylinder but with 787.4 mm to a smaller one-inch stroke. Furthermore, the middle cylinder was installed at a slope of 9.5 °, so that its drive rod could be passed over the axle of the first Kuppelradsatzes. The stroke of the outer cylinder was 812.8 mm.

There are historical recordings of the locomotive type, on which can be heard with an emphasis of every third beat a swinging rhythm exhaust the steam engine. This is unusual for a drilling machine with precise 120 -degree offset crank pin exhaust could besides entertainment defects ( faulty steam machine setting ) may also be on the shorter stroke of the inner cylinder together with its shorter Abdampfweg for blowgun related.

The maintenance of the central cylinder was difficult due to its inaccessible location. However, this did not apply to the control of the central cylinder. Alco had acquired a license to use the designed by Sir Nigel Gresley Gresley control ( Gresley conjugated valve gear ). This system allowed the control of the central cylinder on the articulated lever of the control of the outer cylinder derived. The locomotive of the series 9000 were the biggest machines that used this system.

Between 1934 and 1940 they built eight of the fifteen erstgelieferten locomotives by removing the worn Gresleysteuerung the central cylinder and exchanged against a dual control by Walschaerts on the right Lokseite, in which the control drive for the middle cylinder was derived from the double cranked right countercrank. The Union Pacific called this control type as "third link". They resembled the 60000 used by Baldwin in Baldwin steam machine control. In the 1928 -built locomotives, however, the Gresleysteuerung of the central cylinder was equipped with roller bearings, with the older, not the "third link" converted locomotive roller bearings were upgraded from 1940 in this.

During the development phase was initially planned to carry out the wheelsets of the third and fourth Kuppelradsatzes without wheel flanges to improve the trackability of the machines. However, only the fourth Kuppelradsatz was performed without wheel flanges. However, this measure proved to be unnecessary, as was given by the side shift to two inches first and sixth dome axis sufficient Kurvenläufigkeit. Thus were the locomotives until the appearance of the Soviet AA 20-1 machine with the longest wheelbase fixed, in the U.S. and worldwide. What is unusual about the locomotives was that the axes of the forward bogie had the same axle as the driving axles.

The six-axle bogie tender the type of Vanderbilt UP- type 18 -C took 19 tons of coal and 56.5 m³ of water.