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).
The bump test comparison between American-made front springs and standard Woodhead springs.
| Identifier | WestWitteringFiles\G\August1921\ Scan7 | |
| Date | 10th August 1931 | |
| To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to CJ. c. to E.{Mr Elliott - Chief Engineer} c. to Dn. c. to EY. c. to EWT. for R.R.Inc. – ORIGINAL Hal/LG10.8.31. X2628 X3764 PARTS FITTED TO 4.EX CAR IN U.S.A. X3900. The front springs fitted to 4.EX Car were of American manufacture. We removed these from 4.EX Car and have tested them on the chassis on the Bump Test. The average time which the standard Woodhead top plate on the front springs lasts is 12 hours 15 minutes. The length of time the individual top plates on front springs last is from 8 hours to 22 hours. The American springs fitted on the bump chassis - one broke after 23 hours running and the second one is still perfect after running 35 hours. The average life, therefore, of the American springs is considerably more than we get with the Woodhead springs. This is also confirmed by some top leaves for front springs which were sent to us from U.S.A. about 18 months ago and which lasted 25 hours and 27 hours each. We know from our tests that the top leaf of the front spring is the most severely stressed part of the springs so that if the American springs (front) are satisfactory, it is reasonable to assume that they should have no trouble with the rear springs. Attached herewith is Mr. Hall's report on the fractured top leaf on the American spring compared with the top leaf of a Woodhead spring which broke after 10 hours 20 minutes. Hs.{Lord Ernest Hives - Chair} R.R. 238A (100 T) (S) H.{Arthur M. Hanbury - Head Complaints} 159. 11-8-20. G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2800 | ||