sentences:  The "Elephant", a wood-burning type 4-4-0 built by the company in 1849 for the Union Pacific Railroad, had the distinction of being the first locomotive to travel west of the Rocky Mountains.The unit was subsequently renamed the "C.K.Garrison" (an appellation it retained for some 15 years), and ultimately carried the name "Pioneer" beginning around 1870 (not to be confused with the 4-2-0 named "Pioneer" that is preserved in Chicago).