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 implementation of a vacuum-assisted column gear change for the Senior Range, seeking information on its effect on engine idling.
| Identifier | ExFiles\Box 137\3\ scan0240 | |
| Date | 30th April 1940 | |
| 158 SECRET. To Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation} from Ev.{Ivan Evernden - coachwork} c. to Rm.{William Robotham - Chief Engineer} c. to Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer} Ev.{Ivan Evernden - coachwork}10/JH.30.4.40. re Column Gear Change. Senior Range. It has been decided to fit to the L.H. Silver Phantom 31.G.VII. our scheme of Vacuum assisted column gear shaft. The vacuum cylinder is shown on PL.79 of which you will have received a print. The cylinder is 3.500 in. bore and has a stroke of 1.125 in the worst case of changing into a non-synchromesh gear. The pipe line is approx. 3 ft. long and 3/8" inside diameter from the cylinder to the induction pipe and this pipe is always at induction pipe depression. We have arranged our leverages on the assumption that on the average a change will be made at an induction pipe depression of 5.2 lbs.sq.in. of vacuum. The loads on the valve linkage are given on PL.79. We are interested to know :- (1) Will the introduction of air into the induction pipe spoil the engine idling at the moment of engaging a gear? (2) What is the best point on the induction pipe to put the vacuum pipe to the change speed cylinder. It will be seen on PL.79 that there is a clearance volume at the end of the stroke, also, the piston will halt during its stroke for the period of synchronisation, but this halt will have a very short duration if the change takes places properly. We have estimated the normal time for a gear change as 2 seconds. Ev.{Ivan Evernden - coachwork} | ||