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).
Investigation into an imbalanced Phantom III crankshaft, flywheel, and clutch assembly causing vibrations.
| Identifier | ExFiles\Box 93\5\ scan0119 | |
| Date | 4th April 1936 | |
| To RHC.{R. H. Coverley - Production Engineer} x317 Hs{Lord Ernest Hives - Chair}/Std.1/JH.4.4.36. Balance of Ph.III Crankshaft, Flywheel & Clutch Assembly. As you are probably aware, we recently experienced trouble on 33-LX car, due to vibrations caused by the crankshaft, flywheel, and clutch assembly being out of balance. This was rectified temporarily by adding a stud to one of the withdrawal holes. This cures the vibration. We have had the above assembly removed from the engine and have checked it for balance on the shop strips and on the Trebel balancing machine. On the strips, it is very nearly correct with the above mentioned stud in place, without it, it is definitely out of balance. On the Trebel machine, the assembly is 4.7 oz/ins out of balance at flywheel end of shaft with stud in position, and 8.0 oz/ins. out of balance at flywheel end without stud. These figures mean that, (1) Static balancing is only accurate to approximately 4 oz/ins. (2) The assembly as fitted in car without the additional stud was not in correct balance. As regards point (2) this occurred because the shaft assembly was originally balanced by the shop with an inertia ring fitted to the flywheel. Holes were drilled in this ring to correct the balance. This ring was afterwards removed by the shop and the assembly was not rebalanced. | ||