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).
Investigation into noisy 30 HP dynamos rejected by the Repair Department after overhaul.
| Identifier | ExFiles\Box 165\6\ img127 | |
| Date | 22th March 1927 | |
| RR 238(150 BKS.) (BH57.29-6-20.) MP 224358 ROLLS-ROYCE LTD. INSTRUCTIONS. To E.E.C Order No. A.C. 84. Customer's No. x X5660 22nd March 1927. Noisy 30 h.p. Dynamos from Repair Dept. Five machines, all of 24 coil type, were received from Mr Brock for investigation as having been rejected by the Repair Dept. after overhaul, on account of noise. Various tests were made as detailed below. No 47. Tooth frequency hum at around 870 rpm on load or open circuit. Not loud with machine cold. Bearings good. Side pressure on shaft does not quieten no on some machines. Drag on individual teeth when separately excited very strong. 28 slot armature quiet in this case. Air-gaps found to be slightly unequal. (cont-d) Signed This Sheet must be filed on completion of the work. | ||