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).
Investigation into the cause and solution for breaking ignition distributor driving pins.
| Identifier | ExFiles\Box 108\3\ scan0162 | |
| Date | 23th March 1938 | |
| To RM.{William Robotham - Chief Engineer} from Rm{William Robotham - Chief Engineer}/Wym.{G. Harold Whyman - Experimental Manager} Rm{William Robotham - Chief Engineer}/Wym.{G. Harold Whyman - Experimental Manager}6/RH.{R. Hollingworth}23.3.38. BREAKING OF IGNITION DISTRIBUTOR DRIVING PINS. This investigation was started as a result of 26.G.VI car in France breaking 3 driving pins in approx. 8,000 miles on a Delco distributor and 1 pin on a RR distributor in approx. 3,000 miles. It is difficult to appreciate how these pins were broken in France, as we have run some 35,000 miles on our own Wraith cars in England without a failure, and, whilst appreciating that sustained high speeds are responsible for the breakages, our efforts to reproduce the same conditions resulted in more damage to big end bearings, pistons and clutches, than appears to have been the case in France. We were unable to break either a steel or aluminium driving pin with a spring drive fitted to the crank pinion, because other engine failures occured first, and we had to resort to a solid drive crank pinion before effecting a breakage. Even under these conditions we could not break a pin on the dynamometer, and so we went to Donnington track, still retaining the solid drives, and ran the car at 4400 R.P.M. in 2nd. gear for 10 mins. when the steel pin sheared. Having thus found a means of breaking the driving pin, but bearing in mind that we were breaking big ends and clutches quicker, we decided to continue our tests with Aluminium driving pins. We were able to shear these on both the Delco and RR distributor in 2 and 3 mins. respectively. We then fitted the small spring drive to ECD.513 to the distributor itself and succeeded in running for 20 Mins. without any detrimental effect to the Aluminium pin. This we consider to be very satisfactory, and suggest that provision should be made for a distributor spring drive on both Wraith III and Bentley III production cars. Rm{William Robotham - Chief Engineer}/Wym.{G. Harold Whyman - Experimental Manager} | ||