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).
Letter from Ford Motor Company Limited discussing the physical condition and wear patterns of gears, specifically addressing 'cross-bearing' and 'stepping' phenomena.
| Identifier | ExFiles\Box 136\1\ scan0257 | |
| Date | 17th November 1937 | |
| Messrs Rolls-Royce Ltd., DERBY. 17 Nov 1937 - 2 - be employed by reason of cost, a more uniformly good production of gears can be obtained by using an open weave cotton such as Messrs Attwaters 5 ozs. "M" fabric, than by employing cotton duck. PHYSICAL CONDITION OF THE GEAR. We think the following comments should prove useful. Firstly, not only is the phenomenon of"cross-bearing" in evidence, but the wear at the centre of the teeth is greater than at either edge. Clearly the mating surfaces cannot have been complementary to each other under running conditions, and this would imply either tooth flex in service or initial faulty cutting. The excessive relief at one end only of the teeth would suggest the latter condition. Secondly, it is commonly accepted practice that where fabric gears are mated with steel gears the latter should overlap the former to prevent the phenomenon of stepping which is so much in evidence with the gear under examination. We are of the opinion that more satisfactory resistance to wear (without sacrificing silence) is obtained by using a coarser pitch gear, as we have found that the fine teeth tend to distort under load and this results in uneven and excessive wear. A sample section of the camshaft gear from one of our 8 h.p. motors is enclosed to illustrate the tooth size we are now using. We trust that this is what you require. Yours very truly, FORD MOTOR COMPANY LIMITED [Signature] General Manager ARS:S | ||