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).
Notes on gear lapping processes, gear production machines, and specifications for helical gears.
| Identifier | ExFiles\Box 170\2\ img044 | |
| Date | 15th May 1931 guessed | |
| iron out the variabilities. (3) An extremely good cutting job with an oil hardened steel followed by 1 minute for lapping is indicated as a very fair production process. For superfine work one might anticipate, hob, Lees-Bradner grind, and 1/2 minute per lapping. In no case is there any finishing of bore after lapping. The Gear Process have now two new things:- a) For large production a machine without widex in which the gear just does not come out of the lap either end. The correction of widex is therefore due to an averaging of spacing errors in the large quantity of gears lapped. b) A new and better indexing device on the work table instead of on the ram. (5) Successful helical gears all have 45° helix angle. They nearly all have normal pressure angles of about 12°, i.e. thin "steep" teeth. Pitches vary from 7 p. normal down to 16. The finer pitches are favored but are more expensive. They prove under static test & shock tests much stronger than was anticipated in spite of the weak looking tooth section. | ||