Locomotives of the Burlington Route's O-5A class were built by the railroad's own West Burlington Shops in 1936-1940 and weighed 461,000 pounds. They had 74-inch drivers and 28x30-inch cylinders, and carried 250 p.s.i. of boiler pressure per square inch. These dimensions produced 67,500 pounds of tractive effort, while the large 106.5-square-foot grate area, the 5225 square feet of evaporative heating surface and the 2405 square feet of superheating surface rendered these engines capable of sustained operation at speed in both freight and passenger service. No. 5629, which is displayed today at the Colorado Railroad Museum near Golden, is shown here in a scanned image from the 1951 edition of World Railways.