BS ISO 20816-9:2020 pdf free.Mechanical vibration——Measurement and evaluation of machine vibration.
The vibrations of a gear unit can be measured in two ways, i.e. on the housing [casing) or relative to the shafts. Housing vibration measurements are preferred for gear units operating with rolling element bearings when the clearance in such bearings is small and little relative movement normally occurs between the shaft and housing. Both shaft and housing vibration measurements are usually made on gear units operating with plain journal bearings (fluid-film bearings). Shaft vibration measurements can provide detailed information which is sometimes not evident from housing measurements, but only over a limited frequency range (typically up to 500 Hz). Care shall be taken when choosing the measurement instrument to be used for a given gear unit and operating conditions, as each instrument has its own characteristics (see Annex C). Where possible, it is useful to combine both shaft and housing vibration measurements to obtain the absolute motion ofa gear or a shaft.Particular attention should be given to ensure that the vibration transducers are correctly mounted and that such mountings do not degrade the accuracy of the measurements. The type and use of vibration instrumentation systems shall conform to ISO 2954 for housing vibration measurement and shall conform to ISO 10817-1 for shaft vibration measurement. The instrumentation should preferably include a facility for time and spectral frequency analysis.The recommended type of transducer for measuring housing vibration is a seismic transducer measuring velocity or acceleration. In order to measure acceleration, velocity and displacement, it is preferable to use an accelerometer. The instrumentation used to acquire the signal should be capable of displaying the root-mean-square (RMS] values of vibration velocity in millimetres per second and the true peak values of vibration acceleration in metres per second per second. The mounting method can affect the frequency response of the transducer; it should therefore preferably be mounted with a screw or stud or using a suitable bonding material. Magnet-mounted accelerometers can be acceptable if the highest fundamental frequency of tooth meshing is less than 2 000 Hz. Hand-held housing measurements are not acceptable for acceptance testing.BS ISO 20816-9 pdf download.