The reliability of a heavy-duty drive used, for instance, in nuclear power stations or in spacecraft is largely determined by the reliability of the gear system. The reliability requirements for components of particular importance are markedly higher than for general industrial applications where standard procedures to calculate a nondestructive probability of 0.99 exist. A new method is proposed for estimating the operational reliability of external-engagement cylindrical evolvent gear transmissions and the associated bearings, permitting the determination of their probability of failure-free operation during the drive's working life. It is assumed that the total number of stress cycles experienced by a gear tooth before failure at specified load has a log-normal distribution. The actual and permissible stress in the tooth under the action of contact and flexural loads is calculated. The margin of strength is used to determine a survival probability greater than 0.99. The probability of failure-free operation of the gear system is calculated as the product of the corresponding probabilities of each gear pair. The proposed method permits the determination of the probability of failure-free operation of a gear transmission to the fifth decimal place, so that the contribution of the gear system to the reliability of the component in which it is employed may be taken more accurately in account. An analogous approach may be adapted in calculating the reliability of the roller bearings supporting the gear shafts, using a Weibull distribution of the probability of failure-free operation. The method described is used in estimating the reliability of solar-cell orientation system of the Universal Space Station.
Reliability of electric drives containing gear systems
Zuverlässigkeit elektrischer Antriebe mit Getriebesystemen
Russian Electrical Engineering ; 75 , 8 ; 31-34
2004
4 Seiten, 1 Bild, 4 Quellen
Aufsatz (Zeitschrift)
Englisch
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