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).
Instruction sheet detailing an investigation into a humming noise in a machine by testing different armatures and bearings.
| Identifier | ExFiles\Box 165\6\ img130 | |
| Date | 29th June 1920 | |
| Customer's No. Y quite uniform. Nº 1143 Hum at tooth-frequency chiefly at cutting in. Commutator and bearing slack. Noise reduced by side pressure on shaft at commutator end. Tooth drag very slight. 57 coil armature no improvement. 34 slot armature hums slightly at about 1000 rpm. Side pressure on shaft of this armature does not further improve. Air-gaps not quite equal. Pole-tip spacing fairly uniform. New bearings having no radial play were fitted to this machine. After that there was considerable hum at about 850 rpm. These tests do not bring out any one Signed (Cont'd) | ||