Evolution and Development of Crankshaft (Pratt & Whitney)-A Study

One of the things that made the original Pratt & Whitney “Wasp” so successful in 1926 when it first passed its type test was the ability to make its power at a higher RPM and a lighter weight than its competition. Key to this accomplishment was the use of a one-piece master rod and two-piece crankshaft. Though two-piece crankshafts had been built before, George Mead and Andy Willgoos chose a new construction consisting of a split crankpin splined to its mating crankpin, the whole assembly being held together with a bolt through the centre of the crankpin. See Figure 5.1.