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).
Test report on servo cam efficiency, comparing the standard 25 HP cams with a modified version to assess the effect of journal friction.
| Identifier | ExFiles\Box 105\4\ scan0157 | |
| Date | 15th November 1934 | |
| Hs{Lord Ernest Hives - Chair}/WJH.14/KW.15.11.34. Servo Cam Efficiency. We have carried out a test on our 25 HP. servo rig to determine the effect of journal friction in the cams. The test consisted of a comparison of the hysteresis of the servo with standard 25 HP. cams and with the same cams with the inner sleeve G.52134 and the outer ball retaining ring G.55341 omitted, as suggested by the Design Dept. The effect of leaving out the inner sleeve is to cause the journal loads to be taken by the ball thrust bearings and by the four balls between the cams. The outer ball retaining ring was left off to ensure that it played no part in taking the journal load between the cams. In operation the cams appeared to behave satisfactorily without the inner sleeve, i.e., they did not pull out of line by more than 0.025". The attached curve Hs.{Lord Ernest Hives - Chair}1608 shows the hysteresis with the two arrangements of the cams. It can be seen that the elimination of the journal friction in the cams causes a very considerable improvement. The servo efficiency is increased from 87% to 93.5%. Hs{Lord Ernest Hives - Chair}/F.J.Hardy. | ||