From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Investigating a humming noise in a machine, considering slack bearings and component accuracy as potential causes.
| Identifier | ExFiles\Box 165\6\ img132 | |
| Date | 29th June 1920 | |
| Customer's No. 6 particular range of speed within which the machine is running, and not much on the armature loading. When noise occurred at relatively higher speeds it was always louder if run on open circuit, the excitation then being very strong. Slack bearings seem as likely as anything to allow humming to occur, but are not always responsible. Side pressure was applied to the shaft of a running machine to simulate the effect of a slackless bearing, but the result did not quite correspond with that of actually fitting new bearings. The accuracy of air-gap and pole-step spacing dimensions does not seem to bear closely on the noise properties of the (Cont-d) | ||