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).
Gearbox design, damper characteristics, and an analysis of Packard's gearbox.
| Identifier | ExFiles\Box 173\4\ img229 | |
| Date | 5th December 1935 guessed | |
| -5- damper is critical, too much being as bad as too little. Spring flexibility is varied by the quality of the rubber. In the steel spring type the inertia is not critical, but the rating of the springs is. The springs have a ground surface, the friction being what it comes when the rating has been determined. The V 8 we tried had no torsional damper. Chunking in the Drive. Packards were inclined to think that the rubber mounting of the gear box had an effect on the chunking. They said they had satisfied themselves that the period of the unit mounting did affect it. Mr. Griswold thought that a very little increase in stiffness or softness of the rubber might make a big difference, especially the latter. We have a drawing of the Packard gear box. It was a remarkably quiet box when tried, though not without chunk. In addition to the close limits on the slacks, previously mentioned, they use gear teeth with 13° pressure angle. The teeth are more than standard height and the reduced pressure angle is needed to give reasonable width of land at the tips of the teeth for casehardening. They use 1 & 1 1/2% casehardening nickel steel. The helix angles are very high, more than 45°, on the constant mesh and 2nd speed wheels and they claim great advantage in quietness. The gears are lapped with a C.I. lap torsionally loaded first on one side and then on the other. No one over here grinds gears now, but with the exception of Packards, gearboxes here have been no advertisement for whatever they do. The free pinions in the Packard box are mounted on angular contact bearings. This sleeve originally straight crumples up under the end load until all slack is taken up and the bearing is slightly preloaded. This collar is then spun into the groove in the shaft serration. Da.{Bernard Day - Chassis Design} | ||