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).
Cause of vibrations in Mr. Johnson's Coupe chassis, 10-LW.
| Identifier | ExFiles\Box 25\3\ Scan064 | |
| Date | 8th March 1921 | |
| To EP.{G. Eric Platford - Chief Quality Engineer} from R.{Sir Henry Royce} c. to CJ. c. to WOr.{Arthur Wormald - General Works Manager} c. to PN.{Mr Northey} c. to Hs.{Lord Ernest Hives - Chair} c. to HL. X.634. R6/G1.8.3.21. X. 634 RE MR. JOHNSON'S COUPE - 10-LW. I have been through the correspondence but cannot find that my conclusion has been arrived at as to the cause of the vibrations, which were thought by Mr.Johnson to be excessive in this particular chassis. Personally, I could not say whether they were excessive, or whether it was a peculiar combination of chassis and body. The reason why I thought this was undoubtedly due to impulses in he engine, and torque reaction, is that it occurred at the usual 18 M.P.H., which would be about right for the 15 toothed axle. I do not think for a minute that the vibration has anything to do with the end of the crankshaft, and I should be very surprised if it was reported to be due to the slack bearings. Regarding crankshaft torsional vibration, I should not expect any torsional period to accur at this speed, so that to my mind it can only be due to either torque reaction, or something out of balance on the crankshaft, or the engine out of line with the gearbox. My own impression was that it would only be reduced by making a less rigid attactment in the frame, so as to lower its period; or by lowering the compression. The reason I believe this phenomenon is rather worse in post-war cars is because the pistons we are now fitting are very gas-tight, and therefore rather more powerful impulses at Contd. | ||