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).
Testing balanced crankshafts to resolve flywheel wobble and the resulting production and design implications for various models.
| Identifier | ExFiles\Box 14\2\ Scan130 | |
| Date | 21th August 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 By.{R.W. Bailey - Chief Engineer} 67010. Hs.{Lord Ernest Hives - Chair}4/MJ.21.8.31. BALANCE WEIGHTS. R.4/M17.8.31. X.7010. X.5010. We had received instructions from W.W. to try a completely balanced crankshaft including the big end in order to be able to say definitely what effect this had on the flywheel wobble. These tests have in no way interfered or been responsible, for the delay on the previous crankshaft instructed by W.W. with eight balance weights. The car you are running at W.M. is fitted with this scheme applied temporarily to a crankshaft machined to the present design. The new forging with the proper fixings to take the balance weights is promised for September the 5th. On the car engines, what must be realised is the fact that owing to sales falling off so much the time taken to introduce features on the car is going to be increased. At the present rate of production of the 25 HP., "T" Series will not be completed until next April. A decision will therefore have to be made as regards whether we are going to scrap a lot of crankshafts, or whether we can make a satisfactory scheme to apply balance weights to the existing crankshaft. "T" Series is no different as regards power output, to the 25 HP. cars we have been supplying for some time. Although there is no question as regards the balance weight saving on bearings we have got to say that the wear on bearings does not figure in any of the complaints received from Service Depots. The 25 HP. car which last ran in France and on which the bearings suffered considerably, had the crankshaft with a large diameter pin. This crankshaft is not being used on "T" Series. The position of the Phantom is about the same, that is, the present stock of crankshafts at the present rate of sales will carry us on for approximately nine months. In the case of the Phantom car we know it would not be safe to add any appreciable amount of balance weight to the shaft because of the risk of breakage. It is hardly fair to compare the cars with the "R" engine. In the case of the "R". engine we have scrapped about four supplies of crankshafts and changed the design, sparing no expenses, but this would hardly be feasible on the cars. Hs.{Lord Ernest Hives - Chair} | ||