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).
Analysis of issues with gear and pinion mounting, bedding, and grinding on Units B.6 and B.7.
| Identifier | ExFiles\Box 136\1\ scan0106 | |
| Date | 24th October 1933 | |
| -3- Hs{Lord Ernest Hives - Chair}/FJH.{Fred J. Hardy - Chief Dev. Engineer}7/KT.24.10.33. (b) Helix angle of gear teeth not correct. There probably is a certain amount of (a) on Unit B.7. as in the case of the hardened pinions the bedding was at the back for a greater part of the circumference than it was at the front. Whether or not the helix angle was correct cannot be decided as no steps were taken to determine the bedding on the rig. The gears on Unit B.6. gave results identical to those of the original hardened gears on B.7. Owing to lack of time, no experiments were made on the gears, apart from proving that the pump pinion was the only noisy gear. The trouble experienced with the pump pinions on B.6. and B.7. has emphasised the need for accurate mounting of the gears. The arbours on which the gears are mounted on the lapping rig are not sufficiently true. They should be ground true with the shaft running in its own bearings. The use of separate bushes fitting over the arbours and inside the gears should be avoided wherever possible. The gears should always be mounted on the lapping rig so that they run true to the bore and not true to the pitch line as has been done up to now. The gears will, or should, run true to the bore on the engine. If the pitch line of the gear is not true to the bore it is better to find this error on the rig than on the engine. In hardened gears the bore is ground after hardening and great care should be taken to ensure that it is ground square with the face of the pinion that was used for locating the gear when cutting the teeth. The face of the pinion mentioned above should be ground before cutting the teeth. The arbours on which the gears are mounted for cutting the teeth could be kept in better condition. The trouble with the hardened pinions on Units B.6. and B.7. was almost certainly due to errors in grinding | ||