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).
Letter discussing stress testing and strength requirements for back axles following a failure.
| Identifier | ExFiles\Box 49\1\ Scan028 | |
| Date | 27th October 1912 | |
| COPY. FHR2/H271012 GRAND HOTEL DU CANADEL, Par le Lavandou, (VAR), 27th October 1912 Mr Johnson from F.H.R. for T.C. & Mr Barrington (Experimental Dept.) With reference to the cracked axle tube 1926. This is nothing more than we could expect, and I was very pleased to learn that the axle stood so much of the bumping test. If we take as a requirement of strength the strength of the 1400 type axle as being all that is necessary in a horizontal plane, we can repeat the bumping test which destroys this on the new light axle, which I hope and believe will be able to stand it quite well, although the axle tubes are smaller in diameter our idea at the time being to make them equally as strong as the torque tube. We have 3 main stresses to stand up against in back axles. 1. Bumping over rough road, to test which I suggested some time ago that we should have a pair of wheels (inexpensive) with solid tyres, and other tests already in hand. 2. Torsional control of the back axle by torque tube, the stresses on this have proved greater than anticipated (but it was always intended to be stronger than the transmission) owing to the over-vigorous and unsteady working of the brakes. Revolving test in the lathes, sudden skidding of heavy wheels and other tests are now available to prove strength. 3. Stresses in horizontal plane, such as would occur in backing one wheel against kerb and wheels catching obstructions on the road. The strength to resist these stresses can be tested by the axle bumping test and the standard of strength should be equal to cars of series 1400, better if it entails no excessive weight. [Handwritten in left margin: X339] [Stamp: RECEIVED] [Stamp: W.Md. OCT 28 1912] | ||