The Production of High-Speed Helical Gears, with Special Reference to the Elimination of Transmission Noises

Abstract

The paper records experience gained in the production of quiet-running high-speed helical gears. Sources of gear noise, and the early attempts at their elimination, are briefly stated, together with experiments of a similar nature with which the author has been associated. High-frequency noises, either due to the number of contacts per second or to the indexing wormwheel of the hobbing machine, are distinct from, and more irritating to the ear, than indeterminate noises due to rough running. Ear reaction to gear noise is dealt with, and a method of producing gears is given whereby the noise pulsations are made high enough to be less objectionable to the ear. Hobbing machines with the indexing wormwheel and table solid are advocated, as opposed to machines having the “creep” mechanism. One firm's experience along these lines is given, together with a description of the method which they adopted to eliminate some causes of gear noise. Examples of sets in service, and of their tooth loads and noise levels, are given, as well as special analytical test figures.