The Colorado & Southern's class B-4R Consolidations had 57-inch drivers, 22x28-inch cylinders and a boiler pressure of 200 p.s.i. With these dimensions they produced a tractive effort of 40,400 pounds, and they weighed about 185,000 pounds. No. 634, shown here switching at the Denver terminal on August 14, 1957, was delivered by American Locomotive Company's Brooks Works in 1906 and was dropped from the Burlington Route system roster in December 1960. No. 641 of this class worked the Climax-Leadville branch until October 1962, becoming the last steam locomotive in regular operation on a Class 1 railroad in the United States. It, and No. 638, are preserved and displayed today in two Colorado locations.