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 to The Adamant Engineering Co. Ltd. discussing the reasons for tight spots on a large double tooth Marles gear.
| Identifier | ExFiles\Box 28\3\ Scan161 | |
| Date | 30th May 1935 | |
| X1300 Exptl. Dept. Ha/FJH.{Fred J. Hardy - Chief Dev. Engineer}18/KW. 30th May, 1935. The Adamant Engineering Co.Ltd., Dallow Road, LUTON. For the attention of Commdr. Matravers. Dear Sirs, On the occasion of your last visit to Derby you discussed with us the reasons for the tight spots on the large double tooth Marles gear. As a result of this discussion it was agreed that, even with a perfectly central cam, there would still be two slightly tight spots either side of the central position, or, alternatively, a very small amount of play in the central position. The writer has been reconsidering this matter recently, and has come to the conclusion that he cannot agree with this for the reasons explained below: The attached print shows the gear diagrammatically for the purpose of explanation. It is assumed that there is sufficient clearance on the faces B and C to ensure that these do not make contact while both teeth of the follower are within the track of the cam. If the rockershaft moves clockwise as shown in the sketch, then the side A moves deeper into mesh as it approaches the central position. If binding is to occur then both faces A and D must become tight, but, as A moves towards the central position, D moves away from this position, and, according to our analysis of the geometry, face D comes out of engagement by a greater amount than A goes in. Therefore binding cannot occur and there can be only one tight spot in the gear and that is in the central position when A and D are symmetrical about the centre line. | ||