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).
Failure of American-made springs due to faulty heat-treatment.
| Identifier | ExFiles\Box 43\2\ Scan035 | |
| Date | 2nd September 1921 | |
| X3900 RECEIVED Na{Mr Nadin}2/S2.9.21 Sept. 2, 1921. C.C. Mr. Hives Mr. Olley Mr. Claude Johnson, Managing Director, Rolls-Royce, Limited, 15 Conduit Street, London, England. Attention Mr. Royce. Re: Springs made in U.S.A. With reference to Mr. Hives' memo Hal/L.G.10.8.21 re the above subject, I would like to make a suggestion. We have inspected 10 or 12 broken springs taken from English cars; some of the plates have been back plates, others have been intermediate plates. In every case we have found the fracture to have been more or less crystaline and in some of the split back plates, fractures were very crystaline indeed. We made a series of heat-treating experiments on the broken spring plates and found, by using the correct heat treatment for the steel, a smooth silky fracture could be obtained. We found, in fact, that the faulty English steel was only faulty, due to heat-treatment and that it could be made equal to, or better than, the steel used by the American Spring-makers. I therefore want to suggest that the whole of the trouble with Woodhead springs and their comparatively short life on the dynamometer, is due entirely to faulty heat-treatment. I do not know what methods are now employed by Woodheads in their heat-treating department, but, on the occasion of my visit there, some years ago, the furnaces were extremely crude and the tempering was done by means of a piece of charred stick. For the first quench, the Spring-makers here employ modern oil fired furnaces with 2 or 3 pyrometers to control the temperature and secure uniform results. For tempering, a furnace with an endless traveling chain is used and 4 or 5 pyrometers are used through the length of the furnace. | ||