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).
Causes and potential solutions for transmission rattle.
| Identifier | ExFiles\Box 178\3\ img175 | |
| Date | 24th May 1932 | |
| ANS. FROM R.{Sir Henry Royce} C. to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} C. to E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} DY.{F R Danby} TRANSMISSION RATTLE. R3/M24.5.32. X5310. X634. I understand from E.{Mr Elliott - Chief Engineer} that it has now been demonstrated that this has noting to do with the half period, and that according to the inertia of the propeller shaft you can shift its speed. I always assumed that the propeller shaft with its two couplings, and its large and rigid dia., was the balance wheel of the vibrating system, and it received its kicks from the engine flywheel variation in angular velocity, and that the spring was the shaft from the clutch through the gearbox (what we know as the 1st. motion shaft. If we alter this shaft in rigidity, or the torsional inertia mass of the propeller tube we shall get another speed at which the period vibration could take place. In the present state of affairs it seems impossible to make this 1st. motion shaft so rigid that the vibration was at a very high speed, or so flexible that it was at a very low speed so as to avoid it being a nuisance. The use of the damper on the shaft may still be a necessity but we should like one or two other schemes tried before we ask for a suitable design. The most hopeful thing to my mind is a rubber block drive just behind the universal joint, as follows:- the mechanic's universal joint which is close behind the gearbox could be fitted on the propeller shaft so that it could revolve on the propeller shaft with a self lubricated bearing. There would be a star fixed on the propeller shaft and the drive would be taken by suitable rubber blocks enclosed by an end plate. This would give a certain amount of flexibility in the propeller shaft itself between its two couplings, and it would hardly know at what speed to set up the vibration. This would also provide a certain amount of damping. This flexibility would make the drive and gear change kinder, and I think would be much less objectionable than any form of damper we could design. I will get DA.{Bernard Day - Chassis Design} to send you something that could be rigged up temporarily to see whether this would be a cure, and if so I assume it would be applicable to all our cars, made, or to be made. EP.{G. Eric Platford - Chief Quality Engineer} pointed out in a memo. to me that in the Silver Ghost days we fitted a spring coupling between the flywheel and gearbox, and which was friction damped. This seems still to be required somewhere along the line of transmission. R.{Sir Henry Royce} | ||