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).
Axle 'jaggering' (vibration) and twist under various frictional conditions.
| Identifier | Morton\M20.3\ img013 | |
| Date | 20th August 1924 | |
| R.R. 493A (20H) (D.A. 652 20-8-24) J.H.D. -2- Expl. No. 9940 REF: Hs{Lord Ernest Hives - Chair}/AC L/LG2.6.24. EXPERIMENTAL REPORT. jaggering became continuous, the axle would assume an initial deflection of 6° 54', but when jaggering, the total movement would become as above - viz. - 5° 30'. With increased frictional resistance from zero to the point at which jaggers could not be produced, it was found to be more difficult to produce them but when produced it was not lessened in any degree relative to jaggers obtained without frictional resistance. It was noticeable that with increased frictional resistance jaggers occurred at higher road speeds. AXLE TWIST UNDER VARIOUS CONDITIONS WITHOUT APPLICATION OF FRICTION. (1) JAGGERING. Amplitude of vibration 5° 30'. The amplitude of the vibration when the jaggers occurred was the same with all the friction released or with the maximum friction which would not just prevent jaggers (3040 lbs.ins. each side.) Initial twist of axle immediately at commencement of jagger is 9° 18'. This apparently takes place when brakes self-lock and imparts to the spring sufficient energy to start the jaggers. These tests were carried out on a chassis with only front brakes fitted - if four-wheel brakes have had been used and a heavy body, the twist might be worse owing to the extra weight thrown on the front wheels. The 9° 18' is the total movement including that caused by jaggers. (2) TWIST ON ONE SIDE OF THE AXLE RELATIVE TO THE OTHER. One side of the axle was held by locking up the friction device on that side and the twist measured on the other side. It was found to be 4° 6'. It is not safe to assume that this figure is entirely due to axle twist owing to the inability to hold the one side of the axle sufficiently rigid. Jaggers could be obtained with one side of the axle held rigid. Hs{Lord Ernest Hives - Chair}/AJL/ACL. | ||