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).
The failure of a fabric engine coupling on chassis 18-XJ and a discussion of its design.
| Identifier | ExFiles\Box 15\4\ Scan072 | |
| Date | 2nd October 1930 | |
| Pt.7/PH/2-10-30. By.{R.W. Bailey - Chief Engineer} Derby (Copy to Whr.{Mr Wheeler} London Hs.{Lord Ernest Hives - Chair} Derby, Hd.{Mr Hayward/Mr Huddy} ") We have just experienced our first trouble here in connection with fabric engine coupling about which we have received several Sheets from Repair Department, but as usual, no material to enable us to cope with same. The chassis affected is 18-XJ, and we have had to dismantle gearbox and remove collapsed fabric disc, replacing same with locally purchased material, in order to keep customer on the road. Unfortunately it is impossible to purchase any Australian discs similar to that originally fitted, and we have therefore had to make the best of a bad job, making up a coupling compounded of 3 narrower discs which are slightly in excess of the width of the original overall, but slightly less in outer diameter, also slightly greater in inside diameter. It is pretty obvious that the reason for the collapse of this fabric coupling is not in any sense due to it having been called upon to act as a universal joint, but is solely due to the resistance of the transmission to engine torque. It is apparent that there is a certain amount of radial flexibility in the fabric couplings, because as there are 6 alternative studs, 3 being drivers, and 3 being driven, this flexibility is demonstrated by the fact that such areas of the fabric coupling lying between those studs as are in tension are unaffected, while such areas as are in compression are forced apart and disintegrated. It seems to me that in designing this coupling Rolls-Royce only had in mind the provision of a silent and somewhat radially flexible drive requiring no lubricant, and that they had no intention whatever of making use of the universalling properties of the joint at all, because in this location there is no need to make provision for this. Under the circumstances, therefore, it would seem that as the coupling is not called upon to flex in a universal sense, it could easily be made much more rigid in a torsional sense by increasing the areas of the rivetted plates. | ||