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).
Analysis of deviations in standard camshaft profiles and their effect on exhaust valve lift and velocity.
| Identifier | ExFiles\Box 17\6\ Scan259 | |
| Date | 21th June 1934 | |
| -4- Hs{Lord Ernest Hives - Chair}/Smth.23/KW. 21.6.34. A standard camshaft (E.82448) was taken from production and the profiles of the 4th, 5th and 6th exhaust cams were measured. With this type of camshaft the 5th exhaust valve had the least tendency to ride, whilst No. 6 had the greatest. The 4th exhaust valve was practically as bad as No. 6. The accompanying table (Fig.2) gives the departures from the designed profile. It will be seen that at the 1st changeover point the lift on No. 6 exhaust cam is 15% more than the designed figure. Furthermore the magnitude of errors in the profiles of the three cams are related to the tendency for the corresponding valves to ride. Examination of the actual and theoretical valve lift diagrams shows that the effect of the deviations in the lift is to distort the velocity diagram towards the opening side as shown on Fig. 3, but there does not appear to be any appreciable effect on the accelerations. We are now examining the cam forms on which the errors should be magnified. Hs{Lord Ernest Hives - Chair}/F.Ll.Smith. | ||