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).
Dissatisfaction with a 6-cylinder engine, focusing on crankshaft torsional vibrations and damper design.
| Identifier | ExFiles\Box 137\4\ scan0318 | |
| Date | 14th April 1931 | |
| E.{Mr Elliott - Chief Engineer} BY.{R.W. Bailey - Chief Engineer} HS.{Lord Ernest Hives - Chair} ) FROM R.{Sir Henry Royce} (At Le CanadelHenry Royce's French residence.) X634 R3/M14.4.31. C. to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} C. to RG.{Mr Rowledge} LHS.{Lord Herbert Scott} PN.{Mr Northey} Mr. Claremont. CAR ENGINE. I am now almost certain that our dissatisfaction with the 6 cyl. engine is due to the following: (1) Torque reaction. (2) Crankshaft torsional vibrations. (3) Whirling flywheels. Referring to (1) this is very difficult to avoid, but only manifests itself at low engine revs: it can be best improved by the double top. In our large car it does not worry us after 25 MPH. Referring to (2) I am alone in bringing this up as our present trouble with P. 2. at 37 and 50/60 MPH. It was originally found by me in our 30 HP. in 1906. and in experimenting to prove what it really was I came across the cure of the damper flywheels fitted to all our 6 cyl. engines and now universally used by nearly all makers. In our early work we used the friction of dry surfaces, and Lanchester some 5/7 yrs. later invented his damper with very large surface lubricated, but later I believe changed to nearer our scheme of spring loaded surfaces instead of viscosity only. Now for some time (owing to troubles with spigot seizing) we have arranged for this part to be well lubricated and it is possible this has spoilt its efficiency. (I wired Derby a second telegram that I feared lubricated damper inefficient, and to try dry. I am sending toWW. design for simple one centrifugally loaded.) One must imagine that to act at all such a device must allow the crank to deflect and scrub at the friction surfaces and therefore the device cannot be perfection, and may fall much below its best possible, and this is where I think we are. We have long known that we must not give the slight est torsional slack so that the surfaces intended to scrub must not be yielding, such as deep rubber or cork, and the best of some rigid material like hard grey rubber fibre or hard wood. I have always found thin vulcanised fibre good if clearance is made for its change in bulk with humidity. I have now come to the very definite conclusion that dry friction is far better than lubricated, for the reason that after the lubrication has worked between the | ||