[...]... problems of design, metrology, development and troubleshooting when noise and vibration occur In this area the standard specifications are of no help, so it is necessary to understand what is happening to cause the noise It is intended primarily for engineers in industry who are either buying-in gears or designing, manufacturing, and inspecting them and who encounter noise trouble or are asked to measure... of gear noise is based on the experience of nearly 40 years of researching, consulting, measuring and teaching in the field of gears, mainly biased towards solving industrial noise and vibration problems When a noise or vibration problem arises there is usually a naive hope either that it will go away or that slapping on a layer of Messrs Bloggs1 patent goo will solve the problem Unfortunately, gear. .. 271 272 273 276 277 278 279 280 19 Strength v Noise 19.1 The connection between strength and noise 19.2 Design for low noise helicals 19.3 Design sensitivity 19.4 Buying problems 281 281 282 285 286 Units 289 Index 291 Causes of Noise 1.1 Possible causes of gear noise To generate noise from gears the primary cause must be a force variation which generates a vibration (in the components), which is then... forces will be negligible if there are spur gears, double helicals, or thrust cones Single helical gears (and right angle drives) give axial forces and, unfortunately, the end panels of gearcases are often flat and are rather flexible The resulting end panel vibrations are important if it is the gearcase which is producing noise, but of little importance if it is vibration through the mounting feet that... BEARING FORCES I Casing Casing Stiffnesses Damping I GEARCASE FOOT VIBRATIONS ^ Antivibration Mounts I TRANSMITTED STRUCTURE VIBRATION 4 Sound Radiating Panel 4 AIRBORNE NOISE Fig 1.4 Vibration excitation and transmission path 1.6 T.E - noise relationship It is very difficult for a traditional gear engineer trained to think in terms of pitch, profile, and helix measurements to change over to ideas of... between the gears [Fig l(b)] can occur with unusual gear designs such as cycloidal and hypocycloidal gears [2] but, with involute gears, the direction variation is only due to friction effects The effect is small and can be neglected for normal industrial gears as it is at worst a variation of ± 3° when the coefficient of friction is 0.05 with spur gears but is negligibly small with helical gears For... good isolation between blades and gears In a car, the trouble path can be upstream or downstream, as vibration from the gearbox travels to the engine and radiates from engine panels, or escapes through the engine mounts to the body shell, or travels to the rear axle and through its supports to the body At one time the vibration also travelled directly via gear levers and clutch cables into the body... manufacturing errors, design errors and tooth and gear deflections to generate the T.E Though manufacturing errors are usually blamed it is more commonly design that is at fault The T.E is then the source of the vibration and it drives the internal dynamics of the gears to give vibration forces through the bearing supports In turn, these bearing forces drive the external gearcase vibrations or, via any isolation... internal responses of the gearbox, the input is the relative vibration between the gear teeth and the outputs (as far as noise is concerned) are the vibration forces transmitted through the bearings to the gearcase In general the "output" force through each bearing should have six components: three forces and three moments, but we usually ignore the moments as they are very small and the axial forces will... Causes of Noise 5 (c) The base pitches of both gears must be the same (except for tip relief) so that there is a smooth handover from one pair to the next (The base pitch of a gear is the distance from one tooth's flank to the next tooth's flank along the line of action and so tangential to the base circle.) If gears were perfect involutes, absolutely rigid and correctly spaced, there would be no vibration . Chillers and Cooling Towers: Fundamentals, Application, and Operation, Herbert W. Stanford III 157. Gear Noise and Vibration: Second Edition, Revised and Expanded, J. Derek Smith 158. Handbook . Carlson 16. Industrial Noise Control: Fundamentals and Applications, edited by Lewis H. Bell 17. Gears and Their Vibration: A Basic Approach to Understanding Gear Noise, J. Derek Smith 18. . Transmission and Material Handling: Design and Appli- cations Handbook, American Chain Association 19. Corrosion and Corrosion Protection Handbook, edited by Philip A. Schweitzer 20. Gear