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 the cause of engine gear whine on a Bentley No. B.5 engine.
| Identifier | ExFiles\Box 136\1\ scan0090 | |
| Date | 19th September 1933 | |
| FILES. X-41 19.9.33. ENGINE GEAR WHINE ON BENTLEY NO.B.5. The crankcase of this engine (B.5) was inspected before erection for alignment of the various gear shafts and no errors were detected. Special care was taken in the cutting of the gears to correct distortion due to carburisation. The rig on which the gears were lapped was measured for alignment of its shafts and found correct. After lapping the gears showed perfect bedding and ran silently on the lapping rig. After erection of the engine and before it had been run the bedding of the teeth was obtained by blue marking the wheels, and was found to be very good. When the engine was started up on test, it was immediately noticed that the gears were noisy. The source of the whine appeared to be the idler wheel. The steel gears were removed, copper deposited and again run in order to be sure of the true bedding. The bedding between the crank pinion and camwheel extended about half way across the face of the gears and almost the full depth of the teeth. The latter condition shows that the teeth were of reasonably correct involute form - hence the silent running despite cross bedding. The bedding between the dynamo pinion and camwheel extended almost the full width of the gears and about one third of the depth. The teeth were therefore not of perfectly correct involute form but gave full width bedding and silent running. The bedding between the idler wheel and camwheel and idler wheel and pump pinion consisted only of a narrow band across about one third of the width of the wheels. The combination of incorrect tooth form and cross bedding gave rise to the noise. | ||