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 from Cleveland Wire Spring Company regarding sample springs and their vibration test results.
| Identifier | ExFiles\Box 19\3\ Scan146 | |
| Date | 22th November 1929 | |
| COPY CLEVELAND WIRE SPRING COMPANY CLEVELAND OHIO November 22nd, 1929, Rolls-Royce of America, Inc. Springfield, Mass. Att: Mr. A.C. Ross Gentlemen:- Fifty (50) sample springs were expressed to you Tuesday processed to the same specifications as one which worked so satisfactorily with your valve train. This spring was found only after numerous trial runs were made with various springs, and is one which we believe you will find a great improvement over your present spring. The samples sent you have the following specifications. 8-1/2 gauge (.155") Electric Furnace Chrome Vanadium Wire 1-1/8" Inside diameter 8-1/2 Total coils 2-15/16" Free length End squared and ground Tempered after coiling. You will note that the spring is coiled with an increase in pitch. In assembling, the low pitch end should be placed against the cylinder block, the high pitch against the retainer. In our spring development work here each spring is charted according to its operating characteristics throughout its entire speed range. In order that you may obtain a comparison between your present spring and the one we sent you, we submit the charts made of each. E-78071 560 R.P.M. Slight Vibration. 580 R.P.M. Slight Vibration. 620 R.P.M. Moderately bad vibration. 690 R.P.M. Moderately bad vibration. 715 R.P.M. Bad vibration with coil clash. 790 R.P.M. Bad vibration with coil clash. 910 R.P.M. Bad vibration with coil clash. | ||