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 variable rate leaf spring technology and disagreements with the Leaf Spring Institute.
| Identifier | ExFiles\Box 154\2\ scan0142 | |
| Date | 8th September 1938 | |
| 1305 C O P Y. from - W.H.Wallace, Eaton Manufacturing Co., DETROIT. MICH. U.S.A. Mr. Frank Woodhead, Sheffield. 8th September 1938. Dear Mr. Woodhead, Your letter of August 30th, enclosing copy of a letter from Mr. A.F.Martindale of Rolls-Royce Limited, has been received. Until very recently the Eaton Manufacturing Company was the largest contributor to the Leaf Spring Institute, when we determined that our best interests were not being served by permitting our name to be associated with certain statements and claims made by the Leaf Spring Institute in regards to the development work on variable rate springs. The leading spring manufacturers of this country decided to pool their efforts with the idea of improving their product and to prevent if possible the inroads the coil springs have been making on their business. This was a project that the Eaton Manufacturing Company endorsed thoroughly, and to which we contributed more than any other spring manufacturer. Unfortunately, the research work was directed by men who knew so little about leaf springs that they believed all of their discoveries were entirely revolutionary, and refused to believe that many well-known facts had been common knowledge prior to their research efforts. They were prone to make certain assumptions and then conduct experiments to substantiate the assumptions made. Their activities antagonised some of the car engineers with whom we do business and when they made claims which cannot be substantiated, we refused to be identified with them any longer. The above will give you the impression that we are not highly enthusiastic in regards to the variable rate rear spring as developed by the Leaf Spring Institute and covered by articles in "Automotive Industries" dated June 25th and July 9th. These articles entirely ignore the fact that a leaf spring of conventional design is a variable rate spring with desirable changes in rate characteristics. For example, the rear spring which we are supplying for Plymouth cars starts in with an initial rate of 130 lbs. per inch of deflection. As load is applied the spring elongates so that under the load of the chassis, body and one passenger the rate has been reduced to 108 lbs. per inch. This rate holds under a five-passenger load when the spring goes into reverse camber and begins to stiffen so that at the time the spring has been deflected to the point where the axle contacts the frame the rate of deflection has built up to 430 lb. per inch. You will note that these rate characteristics are very desirable, giving a maximum of flexibility at the points desired and stiffening to resist both extreme deflection and rebound. | ||