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).
Experiments to cure overrun gear rattles on a 25HP model by fitting a friction damper.
| Identifier | ExFiles\Box 179\2\ img248 | |
| Date | 2nd February 1932 | |
| ORIGINAL I.634. X.5310. R.{Sir Henry Royce} From Ha/Gry.{Shadwell Grylls} c. to SE. Wor.{Arthur Wormald - General Works Manager} c. to W. Da.{Bernard Day - Chassis Design} c. to EV.{Ivan Evernden - coachwork} Ha/Gry.{Shadwell Grylls}/2/MA.15. 2. 32. OVERRUN GEAR RATTLES. 25HP. We have recently been able to carry out further experiments on this trouble on a customers car that had a very bad rattle from 52-48 m.p.h. on the overrun. This rattle was so bad that it was not eliminated by running full throttle with the engine switched off. Previous tests had shown that an inertia of 100 lbs-ins^2 added to the propeller shaft greatly reduced the rattle in intensity and at the same time lowered it to 30 m.p.h. On this occasion we fitted to the flange at the rear of the gear box a friction damper of 80 lbs-ins^2. This entirely cures the rattle. The damper using dry friction could be set at loads varying from about 11 lbs at 4" radius to solid. In the latter condition a rattle could just be heard at 33 m.p.h. With a setting of 22 lbs which allows for a wide margin of error and also for alterations in poundage due to temperature effects, the damper is entirely effective, no rattle being audible at any speed. This particular damper can only be fitted to old type cars that have no Y brackets supporting the rear of the gearbox. Ha/H.Grylls. | ||