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).
Gear tooth lapping operations, interference, and contact, with a comparison to Cadillac and LaSalle transmissions.
| Identifier | ExFiles\Box 22\4\ Scan027 | |
| Date | 2nd April 1935 guessed | |
| -2- This operation due to the greater sliding action above and below the pitch line of the gears causes the bearing of the teeth to come down on the driving teeth and up on the driven teeth. In other words, it tends to cancel the difference in pressure angle which has been ground into the gears. The tips of the driving teeth may at this time show a slight relief due to the grinding wheel not having finished the involute, causing interference, which laps away the tip of mating gear teeth. It is important not to overdo the rotary lapping operation since it finally results in a single pitch line contact. Gears are considered sufficiently lapped when approximately 50% of the operating tooth faces show contact. A chart showing tooth contacts as actually practiced for the Cadillac gears is herewith attached. Our practice for the LaSalle transmission is different due to different lapping method. (Sgd.) E.R.Nyland. | ||