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).
Spring plate Brinell hardness specifications, failures, and acceptable minimums.
| Identifier | ExFiles\Box 87\4\ scan0039 | |
| Date | 1st June 1934 | |
| - 2 - (b). Cont'd.{John DeLooze - Company Secretary} plates below the minimum brinell we specified of 369 were replaced, his view being that this would involve him in replacement of a very large percentage of the springs which he contended was not necessary. Personally I consider it is necessary. Our attitude in regard to this point is based upon the fact that on our spring drawings we specify the maximum and minimum brinell figures to which the plates were to be produced. These figures were not arrived at arbitrarily, but were based on exhaustive tests made under my personal observation on actual spring plates, and I am satisfied that a plate ranging anywhere between 321 to 341 will in the long run fatigue and break. In regard to chassis B.29-AE. the springs of which were brought back by Bn.{W.O. Bentley / Mr Barrington} the top plates of these both varied in thickness from the nominal dimension and were low on brinell, the plates being in the neighbourhood of 321, as against this the Experimental Department have examined their springs and found that on one of the Bentley cars in the Experimental Department where jaggering has been fairly consistent, that the spring was buckled in a similar manner, but in this case the top plates were up to thickness and within our specified brinells. We cannot, therefore, argue that the particular failure which is giving us trouble is solely a question of brinell. In a discussion which was held in Hs{Lord Ernest Hives - Chair}'s Department, with E.{Mr Elliott - Chief Engineer} and myself present, it was definitely agreed by everybody that the conditions of failure were such as to demand an extra clip being interposed half way between the two existing clips on the front springs, and that the plates must be up to thickness, and in future no springs will be accepted which are outside of our brinells, a condition which Mr. Woodhead agrees to, his point of difference being that he is opposed to replacing all the springs which have plates which show a brinell as low as 321. The number of these plates I agree is few, the figure to which most of the plates which are below our specified figure being round about 341, which is, however, in my opinion again still too low, the minimum we should accept being 369. BY.{R.W. Bailey - Chief Engineer} | ||