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 performance and issues of a four-cylinder engine in the 'Ripplet' vehicle, focusing on mounting, vibration, and idling.
| Identifier | ExFiles\Box 118\1\ scan0329 | |
| Date | 4th April 1941 | |
| To Rm{William Robotham - Chief Engineer}/Wym.{G. Harold Whyman - Experimental Manager} from Rm.{William Robotham - Chief Engineer} Copy to Jnr.{Charles L. Jenner} Rm{William Robotham - Chief Engineer}/CB. 1022 Rm.{William Robotham - Chief Engineer}10/ET.4.4.41. FOUR CYLINDER ENGINE IN THE RIPPLET --------------------------------- I was very pleased with the general running of this engine with its present engine mounting. When it has a more effective air silencer, it will be acceptable over a speed range of 10 to 65 m.p.h. The shaking of the engine on clutch engagement will I think be improved by dropping the clutch spring pressure until it matches the torque of this small engine, in the same way that the semi-centrifugal clutch torque matches the 4 1/4 litre Bentley. The idling is bad, but the bad impression which it creates upon the driver is accentuated by the fact that it shakes the steering column. I would be interested to know what has to be done to the mounting to eliminate the shaking, i.e. consider idling only for this particular test and slacking off things until the column shake vanishes. I should like to try the small hydraulic damper which is used to prevent brake thumps, as a means of reducing engine oscillations. There will have to be some rubber insulation between the damper and the engine or it will transmit vibration to the frame. The idling can, of course, be improved without that, but I wonder whether the float chamber level varies too much when the engine is shaking, i.e. when the engine is idling, does the float chamber needle allow the level to rise too much, owing to the petrol pump delivery pressure being high. It would be interesting to know the compression ratio, and of course we know that the combustion chamber shape is not the one that gives the smoothest results, but this is probably all the better for the development of a good engine mounting. Ba/GB. has a big experience of 4-cylinder engine mounting, and I want him to take an interest in what you are doing. There is a fearsome servo jagger on this car, which nearly made me run into something. I think it should be put right before much more road work is done. Rm.{William Robotham - Chief Engineer} | ||