ADVANCED TRANSMISSION COMPONENT DEVELOPMENT

Recently, the emphasis in helicopter gearbox development has concentrated on those design innovations which will permit high temperature operation at increased speeds without degrading strength or weight goals. Several of these design concepts are discussed in this paper. One avenue of investigation, which shows promising strength or weight advantages, is high contact ratio gearing. The means taken to obtain a high contact ratio tends to produce an inherently weaker tooth and reliance must be placed on the multiple load-sharing feature of this design to achieve an advantage over low contact ratio gears. This paper discusses the appropriate consideration which must be addressed in the design stage to achieve optimum results. To provide high temperature capability, two (2) UH-60A helicopter main transmission housings, were fabricated from a stainless steel alloy to replace the conventional magnesium alloy casing. Design details and fabrication procedures are discussed.