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).
'SS' and 20 HP engine mounting, frame flexibility, vibrations, and proposed rubber-based solutions.
| Identifier | ExFiles\Box 14\8\ Scan106 | |
| Date | 4th January 1929 | |
| +7380- R1/M4.1.29. Hs.{Lord Ernest Hives - Chair} E.{Mr Elliott - Chief Engineer} BA. EY. from R.{Sir Henry Royce} c. to BJ. Wor.{Arthur Wormald - General Works Manager} Sg.{Arthur F. Sidgreaves - MD} c. to FN. CWB. C. 'SS{S. Smith}' AND 20 HP. X.7005 ENGINE MOUNTING ETC. X.5005 X.7380 Apparently there was truth in the idea that the frame (radiator) movements were of large amplitude, and the engine vibrations of small amplitude, and that we might find an engine mounting that would prevent the former, but not transmit the latter, by reducing the flexibility. One gathers that our mounting was about 100 times too flexible, but we did not know that we needed it to stiffen the frame, and if we had not it would have been excellent for engine vibrations. Now we cannot alter (to any extent) the tramping speed of the front axle at any given tyre pressure, but we now conclude that the axle modifications, the stiffened frame, and effective shock dampers, give us a combination which prevents this axle tramping building up into a high speed wobble: (this at one time seemed an unsurmountable task.) To make the permanent mounting it is probably most economical to use the frame as one of the surfaces because we seem to require a large area so that we can use thicker rubber and make a more robust arrangement. There are 2 simple schemes naturally come to mind - i.e. something like you have, and as that shewn here : The tubular feet (Phantom standard) seem suitable, and as we have these ready I propose we use them as far as possible. The flange which is bolted to the frame can be riveted or bolted to the angle plate that rests on the rubber. It would seem that this flange has a base at the correct angle to the bore to suit the frame. SEE ORIGINAL FOR SKETCH. It would seem advisable to have some design of sheet rubber equivalent to perforated so that it would squeeze down from say .25 to .2 and still leave some cavities : SKETCH. I am suggesting ferrules to allow for say .2 rubber when the inner plate is firmly tightened. Naturally there must be some of the ferrule bolts that fit so as to definitely locate the engine fore and aft. contd :- | ||