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 locomotives. A large increase in firebox area (from on the H-10 to on the A-1), characteristic of his work, necessitated adding another axle to the trailing truck, thus 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. In addition to supporting the very large firebox and grate, the four-wheeled trailing truck carried the ash pan. For this purpose, the truck was redesigned as an articulated extension of the locomotive frame. The result was an ash pan which could hold more ash, allowing the locomotive to travel farther between cleanings. For roads which burned coal, this was a significant innovation. But it was not without tradeoffs. The articulated frame reduced weight on the driving wheels, which did not aid tractive effort (pulling ability). The locomotives so configured also had more difficulty staying on the rails in reverse, particularly through yard trackwork like switch frogs. The locomotive quickly proved to be 26-30% more efficient than the New York Central 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 so 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 Pere Marquette 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.