#4420 is one of fourteen S-4 Class 0-6-0 switchers built for the Union Pacific by Lima in 1914. It was retired in 1957 and donated to the City of Evanston, WY, in 1958, where it went on display on the courthouse lawn. It is now in a play area off Elm Street a few yards north of Oak Street.
#4420 weighs 154,600 lbs, has 19" x 26" cylinders and 51" drivers. It was a coal burner, operating at a boiler pressure of 200 psi delivering tractive effort of 31,290 lbs. It is typical of a "modern" standard switcher produced in the second decade of the 20th Century in the US.
The 0-6-0 dominated switching duties in US railroads right up to WWI, although increasingly heavy freight loads had already brought more orders for 0-8-0 switchers. At the same time, old road engines were often diverted to switching, either as-built or after
their leading and trailing trucks had been removed. Then, after WWI, the success of the USRA 0-8-0
design resulted in a reduction in demand for 0-6-0 switchers. Although orders did continue right into the 1940s, 0-6-0s were generally used on lighter duties and in smaller yards.
