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).
Analysing cam shapes and valve lift curves for chassis 7 CA.
| Identifier | ExFiles\Box 181\M11\ img095 | |
| Date | 7th January 1919 | |
| To DY.{F R Danby} from E.{Mr Elliott - Chief Engineer} Copy to EA. " " EH. URGENT. 3 7th January, 1919. E4/G7119. ORIGINAL RE CAM SHAPES ON CHASSIS 7 CA. X.682. [STAMP: RECEIVED 9 JAN 1919] In connection with transmitting information regarding cam forms, would you kindly note that we have found that the only possible method of doing this, which is of any use, is to send a chart of the VALVE LIFT shewing accelerations, durations of accelerations, and velocities. The ordinary size 4 cam shape drawings which you issue to the shops tell one practically nothing. In connection with the cam forms of chassis 7 CA, we have plotted the CAM LIFTS of exhaust cam E.13667 on to a standard VALVE LIFT chart and we find that this cam has been made four divisions, that is, 8º on the camshaft, shorter than standard. We do not know how high exactly the VALVE LIFT curve for this cam works out, but the CAM curve starts later than the standard VALVE LIFT curve, and crosses the latter at about ten divisions on the chart, then rises above it. The extra area added by this rise is, of course, what we want, but it looks as if this area might have been larger had the CAM been retained at its original length of 72 divisions on the chart, since there would have been a higher jumping off place for that part of the cam which develops the heavy accelerations in the moving pieces. (Contd.) [STAMP: EX. JAN 9 1919] | ||