Lima Locomotive Works - Super Power

Super Power

Success returned to Lima in the 1920s with the new concept of "Super Power" developed by Lima's mechanical engineer William E. Woodard. By making a number of significant changes to maximize a steam locomotive's capacity to generate and utilize steam, Woodard was able to make such locomotives significantly more powerful and faster. He did this by starting in 1922 with the H-10 experimental heavy 2-8-2 design for the New York Central (Michigan Central 8000) and applying both relatively new science (the Cole ratios) every efficiency-enhancing tool available – a larger firebox, increased superheat, a feedwater heater, improved draughting, higher boiler pressure, streamlined steam passages and a trailing-truck booster engine, and by applying limited cutoff (the range of steam valve admission settings) to prevent locomotive engineers from using excessive steam at starting. The 2-8-2 thus produced was demonstrated to be 26% more efficient overall than its immediate predecessor, and the NYC bought 301 copies.

A large increase in firebox area (from 66 square feet (6.1 m2) on the H-10 to 100 square feet (9.3 m2) on the A-1) characteristic of his work necessitated adding another axle to the trailing truck, creating the 2-8-4 wheel arrangement. Built in the spring of 1925, the first Berkshire (a demonstrator owned by Lima) was dubbed the A-1. It quickly proved to be a whopping 26-30% more efficient than the H-10! After a highly successful series of tests in the mid-1920s it was sent around the country to make the idea of "Super Power" known. The first forty-five were purchased by New York Central's subsidiary Boston & Albany following initial road testing across the summit of the Berkshire Hills, and the 2-8-4 wheel arrangement came to be known as the "Berkshire" on most railroads. The prototype itself was later sold to the Illinois Central as part of an order for 50 similar locomotives. Woodard summed up "Super Power" by defining it as "horsepower at speed". Previous design principles emphasized tractive effort (pulling ability) rather than speed. By 1949 some 613 Berkshires had been constructed for North American service, of which twenty are preserved - at least two in operating condition (NKP 765 and PM 1225), both Lima products.

There were at least three successive waves of "Super Power". The first began with NYC 8000 and the A-1, and included Missouri Pacific 2-8-4s and Texas & Pacific 2-10-4s. These locomotives had conventional 63" driving wheels. In 1927, the Erie Railroad took delivery of a "second-phase" Berkshire with 70" driving wheels, capable not only of great power but higher speed; in turn, this design evolved into the Chesapeake & Ohio T-1 2-10-4s of 1930, with 69" driving wheels. The "third-phase" of the later 1930s and war years can be identified with locomotives such as the homebuilt N&W 2-6-6-4s, C&O/Virginian 2-6-6-6 and virtually all American 4-8-4s. Boiler pressures rose as high as 310 lbs/sq.in.; thermic syphons added to the firebox and combustion chamber added 8% to the efficiency of the boiler; roller bearings appeared on main axle boxes and sometimes on running gear. And the "Super Power" concept had extended to other builders such as Alco (the Union Pacific Big Boy) and Baldwin (the Santa Fe 5001- and 5011-class 2-10-4s). The four-wheel trailing truck became the standard for large locomotives (i.e. 4-8-4, 2-10-4, 4-6-6-4, 2-8-8-4).