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).
Vibration tests on various shafts at different speeds and throttle conditions.
| Identifier | ExFiles\Box 74\3\ scan0302 | |
| Date | 23th December 1924 | |
| R.R. 493A (50M) (D.B. 175 25-9-24) J.H.D. -2- EXPERIMENTAL REPORT. Expl. No. REF Hs{Lord Ernest Hives - Chair}/TMW/LG23.12.24. 7-G-11 - Disc shaft. The period comes on sooner than with standard shaft - viz :- 37 m.p.h., lasts to 39 m.p.h., and is more violent, after which the engine is smoother although not vibrationless. On retarding the overrun vibrations are worse, the forward period being distinctly felt again. Test 2. 4-G-11 - Strengthened shaft. (a) throttle closed (b) throttle opened (a) Quite good, very slight vibrations felt 20 to 22 m.p.h. (b) Nothing to pick out at any speed. 7-G-11 - Standard shaft. (a) Slight vibrations start at 17 m.p.h. and continue to increase until at 23 m.p.h. when they are bad. (b) Nothing felt until 19 m.p.h. is reached but from 20 to 23 m.p.h. the vibrations are as bad as when throttle is closed. 7-G-11 - Disc shaft. (a) Vibrations start at 16 m.p.h. and continue increasing up to 20 m.p.h. when they are felt very violently. However, from this point an improvement sets in until at 22 m.p.h. all vibration has disappeared. (b) Small period at 16 m.p.h. another comes on at 18 m.p.h. leaving at 20 m.p.h., after which nothing is felt. The difference however in the relative violence of the vibrations is most noticeable, the throttle closed condition being very bad. However, as this shaft parted at No.6. Conn. rod bearing, after the above tests, it is possible that it commenced to go during the bad throttle closed period. Certainly there was an alteration, when immediately after, confirmation of the 2nd. speed condition was sought, the forward vibrations had disappeared and those on the retard were correspondingly worse. The shaft however parted shortly after, contd :- | ||