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).
Investigation into broken valve springs on chassis 4-YG.
| Identifier | ExFiles\Box 35\3\ scan 034 | |
| Date | 20th March 1923 | |
| x2764 [STAMP: RECEIVED MAR 20 1923] H8 [Initials, crossed out] BJ. [Illegible] c. Hs.{Lord Ernest Hives - Chair} BYG-P20.3.23. CHASSIS 4-YG. Referring to BJ12/H9323, the question of broken valve springs is one which has not arisen previously as a serious item. As a matter of fact, we have had a singularly good time for valve springs on the postwar cars. The fact that on 4-YG, 9 springs out of 12 broke in five weeks is a matter which demands investigation. I take it the springs in question have been preserved and can be sent along to me so that we can try and trace the cause of the trouble. In thinking the matter over it would appear that so large a percentage of springs on one engine breaking must be due to the fact that the car had been driven at fairly high speeds which set up a periodic vibration on the spring itself superposed on the ordinary action of the spring. Practically any spring at some one speed or another will fail if driven regularly at that speed, whereas if the speed were slightly above or below the critical speed in question no failure would take place. With reference to the assurance which was given to H.{Arthur M. Hanbury - Head Complaints} on January 3rd in connection with valve springs, two distinct matters were under discussion; a/- Valve springs as the cause of valve wear. b/- Valves springs as such. In connection with the former we have made very considerable improvements and we think this is the assurance which H.{Arthur M. Hanbury - Head Complaints} is thinking of in connection with the latter. Any remarks which we made at that time were to the effect that we did not know of any real trouble with the valve springs themselves from the point of view of breakage. I am inclined to think that H.{Arthur M. Hanbury - Head Complaints} has taken the assurance in connection with the first item and applied it to the second, as whilst we had no cause for alarm in connection with springs breaking we certainly had not made any particular improvement in our method of manufacture which was likely to react favorably upon this particular fault, whereas we had made considerable improvement upon the manufacture of springs from the point of view of preventing valve wear. BY.{R.W. Bailey - Chief Engineer} | ||