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).
List of improvements and standards for gear manufacturing, grinding, and testing.
| Identifier | ExFiles\Box 136\5\ scan0305 | |
| Date | 3rd April 1937 | |
| -2- RHC{R. H. Coverley - Production Engineer}/AEC.1/LS.3.4.37. consistent with the variations in the amount of stock, (accuracy of .0001 to .0002 is required.) Improvement can be made on the following points:- 1. Hobbing deeper for more grinding wheel clearance. 2. Distortion from hardening must be reduced to a minimum. 3. Bores must be ground more true to the pitch line. 4. The involute part of the tooth form to be ground to its full depth. 5. Better ground finish on teeth. 6. Gears can be ground too quickly for high accuracy. 7. Testing and lapping rigs should have the same style of mounting as the grinding machines. 8. Lapping is necessary and should be done on modern lapping machines. 9. Bores of gears must not be lapped in selective fitting. Finished gears are inspected and passed on the testing rigs by a noise test. It would make for more advancement, if a gear had to be produced up to a certain dimensional standard before submitting for noise test. The standard to includes:- Bedding of teeth. Eccentricity of teeth. Spacing of teeth. Helix angle. Tooth profile. Radial alignment. Special modifications could be incorporated into the above, but must be capable of measurement. When gears are ground to an agreed standard of accuracy, the lapping machine should be responsible for further improvement. Six sets of gears are being made as accurate as possible (but with tip relief,) to arrive at a standard of accuracy for grinding. The style of mounting may be by plain bushes, or splined bushes, each style has advantages, but the most straight forward and likely to be the better is the plain bush. | ||