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).
Design and manufacturing of Gleason gears, focusing on tooth proportions, clearances, and cutter specifications.
| Identifier | ExFiles\Box 49\2\ Scan183 | |
| Date | 13th October 1923 | |
| - 2 - Machines, also from the crown to the cone centre. The proportions of the teeth are calculated at the large end, and it is necessary to have a definite point to enable the teeth to be measured for correct pitch depth and thickness. In addition when fitting up Gleason Gears in axles, the back cone face is used for setting them in their correct position. Another feature which is found necessary from the Works point of view is that sufficient space must be left between the back face of the pinions and the housing so as to enable the fitters to insert a sheet metal guard to prevent grit getting into the pinion housing whilst the teeth are being stoned up. We would suggest that the teeth be strengthened up at the large and small end as shown on sketch below, which would not only prevent the load from getting on the extreme ends but would also avoid the difficulties referred to above. In regard to the proposal to make a larger radius in the bottom corners of the teeth, this again present some difficulty. Generating rack cutters have sharp corners and cannot be rounded off at the points if the standard working clearances are to be maintained. If the standard clearance were increased, then the strength of the teeth would be correspondingly decreased. Although generating rack cutters are made with square corners, they produce radii in the bottom corners of the teeth in gears being generated, but the radius becomes less as the gear approaches the rack, when the corners at the bottom of the teeth become sharp corners. In the Gleason Gears we get a small radius at the bottom of the pinion teeth but not in the wheel, because the latter is practically a rack. If we made the cutters with rounded points, it would be necessary for the Works to see that the radius selected was maintained even in view of the increased clearances which would be required, as already pointed out, otherwise we should get interference between the points of the crown wheel and the round corners produced in the pinions. In accordance with R's previous memo R6/M.13.10.23, we are getting out 11/43 and 13/43 gears in place of the 13, 14, and 15/47 ratio gears which have already been Contd. | ||