Noise of Involute Helical Gears

The problem of involute helical gear noise is studied by running a pair of 6 DP gears in a power circulating rig inside an anechoic room. More than 3500 magnetic tape recordings were taken and analyzed, for gears running at different speeds and transmitting different loads. A pair of 14 DP nickel steel gears of finished, ground, and shaved teeth was also tested to study the effect of surface finish on gear noise. Experimental results revealed that the main sources of gear noise are impact between gear teeth and friction. A sudden rise in noise level has been noticed when a whole number of teeth are in contact. This paper presents experimental results and study of noise of involute helical gears of different facewidths and pitches, running at different speeds, and transmitting different loads. The source of gear noise and noise generating mechanisms are also discussed.