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).
Engine dampers, crankshaft balance, and vibrations.
| Identifier | WestWitteringFiles\T\2July1928-December1928\ Scan217 | |
| Date | 17th November 1928 | |
| HS.{Lord Ernest Hives - Chair} FROM R.{Sir Henry Royce} C. to BJ. WOR.{Arthur Wormald - General Works Manager} BY.{R.W. Bailey - Chief Engineer} (crossed out) ORIGINAL re. ENGINE DAMPERS. R1/M17.11.28. X5010 (crossed out) 5005 X1482 I believe that these should be much tighter than we are generally sending them out. We have tightened those on 10-G-4., and believe they have perceptibly improved this car both in steering and torque reactions. It has occurred to me that sometimes the difference in the feeling of the car from torque reactions and other objectionable vibrations may come through these dampers being insufficiently tight. I do not believe they can be too tight. The subject of engine mounting is one which demands much attention, and is I believe the cause of the difference between many cars. For instance it has always been thought that G.1. is better than G.2. G.1. is on an underframe, and the vibrations do not easily get to the scuttle and dash, and the control is even more rigid in the front than at the back. (A) Regarding Mr. Tresilian's experiments, though it suggests that the deflection of the crankchamber permits the shaft to whip one does feel that it is possible the shaft was not in running balance, though it might have been quite alright in static balance, and if so it would naturally strike a period somewhere in the engine mounting or frame. (B) We should be very sorry to have to return to the balance weights, which we discarded on the Silver Ghost, because we could find no benefit from their use. As applied in that instance the crankshaft is made a running balance without the connecting rods. Since you are working on the 20HP. it would be better to keep to this for comparison, and one has little doubt that a straight shaft with balanced and unbalanced masses representing the crankshaft could be fairly easily made and fitted. The better plan however we think would be to fit up the 20HP. with a complete set of balance weights. The crankshaft suggested by Mr. Tresilian appears very difficult and costly to make, and I doubt whether it could be made commercially. Regarding the heat of the oil, I do not think that balance weights would reduce the oil temperature in the least. (C) Friction resistance of a well lubricated bearing is independent of load until it is overloaded, when it fails, but our bearings in ordinary use would probably give a co-efficient of friction more dependent upon the viscosity of the oil than upon the load on the bearing. Though we have tried to save the bearings in the case of using balance weights and zig-zag crankshafts our chief object has been to save the crankchamber. We shall be sending a design for a set of balance weights for the 20HP. so that you can make a comparison. (D) R.{Sir Henry Royce} | ||