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 and design considerations for crankshaft dampers, comparing dry friction and oily friction types.
| Identifier | ExFiles\Box 138\1\ scan0046 | |
| Date | 13th June 1932 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} c.c. BS.{A J. Barnes - Assistant Manager} WOT. c.c. R.{Sir Henry Royce} Da.{Bernard Day - Chassis Design} c.c. Hy.{Tom Haldenby - Plant Engineer} Y634 Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}/KT.13.6.32. CRANKSHAFT DAMPERS. We will arrange to carry out experiments on the optimum inertia and damping for our crankshaft dampers, and whether dry friction or oily friction proves the better. We think that the criterion of a good damper is one that, without being very sensitive to the friction setting, eliminates the half period without causing the engine to be rough at any other speed. We do not think that a damper of a practical size will ever work reliably on the top period. However, this is easy to prove one way or the other, by first finding the setting required so that the period cannot be felt in the car, and then running the engine on the critical speed on the test bed. On the P.II and the 25 HP, with the friction setting, is also involved the question of timing gear rattles, the minimum friction being determined by the torsional period and the maximum poundage by engine gear rattles. On the 25 HP, the range of setting between these two is very small, on P.II the range is considerably wider. Apart from gear rattles the dampers on both cars are very satisfactory except for the high pressure on the cotton duck on the 25 HP, which amounts to 33 lbs/sq.in as against 15 on RII. No complaints have ever been brought forward against cotton duck in the P.II spring drive. From the point of view of torsional periods the 25 HP. damper operates perfectly at any load between 13 and 20 lbs at 17". On J.III and Peregrine with the timing gears at the back, the damper question should be easier. R.{Sir Henry Royce} is giving us designs of dampers for trying out on J.III in which we can easily alter the inertia and friction setting. One of the dampers is of the dry friction type and the other a multiplate bronze to steel damper running in oil. We will report on the behaviour of them as soon as we can. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} | ||