Naval Gearing—War Experience and Present Development

Abstract

While the reduction gearing fitted in turbine-driven naval ships generally gave reliable service in the 1939–45 war, there were some costly exceptions. Turbine blade failures resulting from vibration, “scuffing” on trials (fortunately cured by hand dressing), and breaking of teeth at the roots, causing extensive damage requiring replacement of the gear-set, were experienced.Examination of these failures revealed shortcomings in manufacture and design, which have now been largely remedied, and it has been possible to establish standards of manufacture necessary to ensure reliability, and to make economic use of available techniques and materials.The use of harder steels hobbed and shaved in a heat-treated condition, or steels, case-hardened and then ground, or, in the very large sizes, air-hardened and ground, now presents no technical obstacle. Gears of alternative designs—hobbed and shaved, or case-hardened and ground—are being made for service at sea. They will be subjected to the same load conditions.Other gears of identical design will be subjected to “back-to-back” tests on shore to investigate their further possibilities.The modifications to pinion helices to compensate for deflexion under load and to safeguard against misalignment, the methods by which they are being applied to these test gears, and the opportunity they provide for making effective use of the full length of pinions, are all examined.