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).
Development and testing of balance weights for 25 HP and Phantom II crankshafts.
| Identifier | ExFiles\Box 182\M19\ img172 | |
| Date | 16th May 1931 | |
| To R.{Sir Henry Royce} From Hs.{Lord Ernest Hives - Chair} c. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. to E.{Mr Elliott - Chief Engineer} Da.{Bernard Day - Chassis Design} c. to By.{R.W. Bailey - Chief Engineer} Hs.{Lord Ernest Hives - Chair}l/WJ.16.5.31. X5010. X634. Referring to - R.2/M12.5.31. As regards balance weights for the 25 HP. we have never yet received a scheme from W.V. to fit balance weights to this engine. In order to get something moving, and realising that we should need them, a scheme was got out in Derby following the lines of LEC.2616 which was sent through in 1928 for fitting balance weights to an existing Phantom crankshaft. The scheme we are using cannot be looked upon as a permanent design as it was got out to fit balance weights to an existing machine shaft. We still therefore require a permanent scheme for fitting balance weights to the 25 HP. engine. The same is also required for Phantom ll. Recently in considering balance weights we have had in mind what value they would have to assist us in overcoming the following faults :- (1) Fuss and boom on Phantom ll. (2) Flywheel wobble. (3) Reduced wear on bearings. After a number of tests both on 25 HP. and Phantom ll we can say that balance weights do not help us as regards No.(1). In this case our tests have been carried out with twelve balance weights but we know this to be a more perfect scheme than the eight balance weights, and therefore the fact that we have used twelve does not influence the result. As regards No.(2) point. This has yet to be proved. On the two cars we have run with balance weights the flywheel wobble has been almost non-existent but we have taken the balance weights off they have still been equally as good so that the position is that the Expl. Dept. have still to prove the value of balance weights in reducing flywheel wobble. With regard to No.(3). There is no doubt about this point but it would need a considerable amount of running in order to produce positive proof, especially as regards the eight balance weights scheme. The other point to be considered is whether with balance weights we reduce the critical period of the shaft to come within the engine speeds attained on the road. | ||