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).
From Detroit detailing observations on axle and gearbox slack causing 'chunking' noise at Buick.
| Identifier | ExFiles\Box 173\4\ img208 | |
| Date | 5th December 1935 | |
| COPY (Memo. from Da.{Bernard Day - Chassis Design}) DETROIT. 5 Dec,1935. To E.{Mr Elliott - Chief Engineer} from Da.{Bernard Day - Chassis Design} As we are hoping to catch the Aquitania on Saturday the chances of a letter reaching England before we do are not great now. We have however learned something that sounds rather promising about chunking, when we visited Buick's at Flint to-day. We saw Mr.Chayne, the Assist.Chief Engineer, and the Transmission and Axle Engineers, whose names we did not get. It appears that the total slack they allow at the tyre rim, with one wheel on the ground, is from 5/16ths. to 9/16ths., and more often the former than the latter. The total slack in the rear axle, measured at the pinion flange is 1° max. They say the principal offender is the clutch hub, the slack in the serrations of which is from .0005 to .0025 they say this is most important. The next important thing is the slack in the rear axle. It appears that if the two ends are thus kept down, slack in the gearbox is less important, though they agree that if we reduce the rear axle slack we may then begin to hear the gearbox. The gears themselves have .008 slack total in each train. Between the sliding jaw clutches on the shaft, by selective fitting is .003, while the jaws of the clutches themselves have from .003 to .010. The rear axle gears have .006 to .010 but are usually .008. The differential gears have from .000 to .005. They took us out in a Buick selected at random, and it certainly did not chunk at all. They do not mind about the end slack in the 2nd. motion shaft, which may be .016 . They have their second speed jaw clutches come out on the overrun, and cure it by taking away the overrun driving face on most of the jaw clutch teeth, leaving only 3 or 4 with full faces. This of course intensifies the pressure and so holds it in. The three or four are of course equally spaced round the pitch circle. The splines are involutes, because they are easy to get to size, but they do not fit on the sides, but on the tops of the teeth, and the bottoms of the female teeth. GROUND ON TOP & SIDES MATING TEETH BROACHED | ||