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).
Test report on spring drive damping, critical oscillation, and gear rattle.
| Identifier | ExFiles\Box 138\1\ scan0085 | |
| Date | 13th December 1933 | |
| -3- Hs{Lord Ernest Hives - Chair}/FJH.{Fred J. Hardy - Chief Dev. Engineer}3/KT.13.12.33. With the rating of 42.5 lbs.ins. per degree there was no evidence of the spring drive hitting its stops. The damping necessary to control the critical oscillation was 1 1/2 lbs. at 1 7/8" and the speed at which the oscillation occurred was 350 R.P.M. The spring drive calibration was 14 lbs. at 1 7/8" in the driving direction and 7 lbs. at 1 7/8" in the overrun direction. With the spring drive in this condition the engine was free from serious gear rattle under all conditions. The insipient rattle over the whole speed range was again in evidence due to the relatively large amount of damping. The spring drive was then tried without the balancing cam. This brought the critical oscillation in again. The damping was increased to 3 lbs. at 1 7/8" but it was still insufficient. Owing to lack of time it was not possible to try the effect of very much heavier damping. All the above tests were run with the fan in use. It is questionable whether the narrow cotton duck washer for the pinion damping will withstand, for any length of time, the heavy loads necessary to produce a damping of the order of 1 1/2 - 3 lbs. at 1 7/8". The spring drive at present on 10,000 miles test will show whether trouble is to be expected with this washer. Further experiments have yet to be carried out on this new damper and these will include the addition of inertia to the crank pinion. Hs{Lord Ernest Hives - Chair}/F.J.Hardy. | ||