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).
Technical memorandum regarding stress issues and proposed design improvements for Wilmot Breeden front bumpers.
| Identifier | ExFiles\Box 118\2\ scan0274 | |
| Date | 18th June 1936 | |
| 7JH BY.3/G.18.6.36. c. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} K1023 RE: WILMOT BREEDEN FRONT BUMPERS. We are in full agreement with Hd{Mr Hayward/Mr Huddy}/SB.{Mr Bull/Mr Bannister}2/ viz. that there is a very high stress set up on the bolt securing both the weight to the spring and the spring to the chassis, but particularly in the case of the former there are indirect stresses resultant from the fact that the bumper itself pivots from a different centre than the spring, as the weight on the spring oscillates from a fixing on the dumb iron, whilst a similar part on the bumper swings from the opposite end of the bumper, in other words one has about a 1/16" radius, the other about 3 ft. radius. We have got out two schemes to deal with this :- (a). An improved method of securing the lead weight, which will eliminate the reduced sections in the bolt itself. (b). A modification to the scheme generally, which we propose to submit to E.{Mr Elliott - Chief Engineer} and for test. In the temporary scheme we keep the section of the bolt increasing from the upper thread to the bottom, and then/the bolt in the nut for a considerable length /spigot on an accurately fitting surface. There are only two threads on the nut by this scheme, the one at the top and the one at the extreme bottom, and the latter is guarded from bending stresses by spigotting in the nut, which itself has a large flange to fit against the surface of the spring. We propose to supply a scheme of this kind to Paris immediately for urgent cases. BY.{R.W. Bailey - Chief Engineer} BM | ||