Union Pacific Challenger

The class of 3900 Union Pacific Railroad, also known as Challenger, was a series of heavy four-cylinder steam locomotives with a simple steam expansion in the joint type. The machine with the wheel arrangement ( 2'C ) C2 ' ( American spelling: 4-6-6-4 ) were intended for the carriage of goods.

The locomotives are a development of six -coupled rigid frame machine class 9000 ( wheel arrangement 2'F1 '). Challenger in the front bogie and the three front driving axles are supported in a movable frame, the rear driving axles, and the three two-axis also delta towing frame, however, in the main frame of the locomotive. From the distribution of the six coupled axles in two groups was to collect less reciprocating mass and thus a higher possible speed. The vehicles received four identical cylinders with dimensions of 56 cm × 81 cm and were maintained at a pressure of the steam boiler of 1,757 kPa designed (255 psi). The first " Challenger " was filed on August 25, 1936 under the number 3900 operating in the railway company " Union Pacific Railroad " in service. In the second delivery of " Challengers " six locomotives for use in passenger trains were equipped. Findings from the construction of the " Big Boys ", which was an enlarged development of the Challengers, were incorporated into the built starting in 1942 improved version of the locomotive. This was cylinder with a diameter of 53 cm, a shorter firebox and a boiler pressure of 1,929 kPa (280 psi). Overall, the Union Pacific purchased 105 locomotives of the series. Other railway companies also ordered the wheel arrangement locomotives " Challenger ", but differing on the basis of other requirements profiles constructively from UP Challenger.

Delivered finishes and applications

Whereabouts

Two " Challenger " locomotives have been preserved: the No. 3985 Union Pacific is the largest operable steam locomotive in the world and leads special tours through; the 3977 (1952 converted to oil firing in 3710 and renumbered ) stands as a monument in a park in North Platte, Nebraska. 41 ° 8 ' 52.1 "N, 100 ° 45' 10.6 " W41.1478 - 100.752945