THE SCIENCE AND APPLICATIONS OF ACOUSTICS - H. H. Arnold ...

382 14. Machinery Noise Controlfollowing speed relationships:with carrier speedn O − n C0 − n C=− D ID On C =n O D OD O + D Iand speed of the balls with respect to the carriern B R = n B − n C =− (n O − n C )D O=− n O R D OD BD BThe frequencies that may occur when the outer race is nonstationary are as follows:1. Shaft imbalance:f = n O602. Outer race defect:3. Inner race defect:f O = n R O ν B60= (n O − n C )ν B60f I = n I Rν B60 = n Cν B604. Defect or damage to one ball or roller:f B = 2n BR60 = n B − n C305. Imbalance or damage in the separator or cage:f C = n C60Harmonics will also constitute additional components of the spectrum.For any bearing fault, the noise and vibration spectra will be essentially tonal,i.e., characteristic peaks will exist. A great deal of the noise energy will be concentratedin the bands that include the fundamental frequency and its first and secondharmonics.14.11 Other Mechanical Drive ElementsChain DrivesFigure 14.10 shows a roller chain meshing with toothed sprockets. The roller chainis constructed of side plates and pin and bushing joints designed to mesh withsprockets. The flexibility of the chain aids in limiting shock and vibratory forces,but the initial contact between the chain and sprockets can be noisy at high speeds.