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 cutting processes, gearbox construction, and gear teeth specifications for Chrysler gears.
| Identifier | ExFiles\Box 19\3\ Scan133 | |
| Date | 11th January 1930 guessed | |
| - 3 - Gear Cutting- All Chrysler gears are cut on Fellows machines. All the internals are roughed to within .002 of tooth-thickness and then "sized" with a cutter which shaves all teeth simultaneously first in one direction and then in the other. This process reproduces the accuracy of the cutter, and has greatly increased the accuracy of the internals. It is a very rapid operation. Externals are finished on the Barnes Gear-Shaver made by Pratt & Whitney. The internals are ground on the backs for the roller races by location from the tops of the teeth. Boxes - The boxes are cast-iron, cast in one piece, and closed by the tower and two pressed steel cover-plates. Neracher considers this cheap but not good construction. The pressed steel covers tend to resonance. For this type of box it would be much better he believes to use no cover plates and to split the cast box on a vertical transverse plane at the middle of the box. This has been done on several experimental boxes. The two halves are dowelled together. The bolt-flange stiffens the box all round in such a way as to overcome resonance. The split in the box also tends to avoid resonance. Assembly is much easier. Aluminum boxes have been built but are not much used, because of expense. No increase in noise has been noted compared with cast iron, but expansion effects round the outer races of the roller bearings are anticipated. These might be easily overcome but the necessary steel housings etc. would increase the cost of construction. Gear Teeth - The gear teeth on the internal trains are, for the smaller box - 19 - 23 and 28 - 32 12 - 15 pitch. 35° press. angle, for the larger - 18 - 22 and 27 - 31 10 - 12 pitch. 30° press. angle. Ordinary involute teeth are used. The short tooth and high pressure angle is used to avoid interference. Errors in centering above .010 begin to produce interference and signs of this have actually been seen on some boxes. - continued | ||