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).
On the manufacturing difficulties of oil damper springs for valve F.80991/2.
| Identifier | ExFiles\Box 55\4\ Scan377 | |
| Date | 20th June 1929 | |
| Y235 Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} C.BY/HBF. (crossed out) BY7/K.{Mr Kilner} 20. 6. 29. RE OIL DAMPER SPRING FOR VALVE F.80991/2. We cannot buy springs to the limits you specify as there are too many variables and the coiling cannot be controlled within the limits necessary to give your results even if we could guarantee the wire diameter being correct as used before and after coiling and heat treatment. We will have to alter the specification so as to leave one factor undimensioned, and the best dimension to leave free is the free length. The only way we can get the accuracy called for is to leave the free length with a wide limit then check each spring for its length at the required load, and tie a label on giving these particulars. We should then fix a size of variable washer to give a constant overall length. This is expensive, and one would think that a limit of 19 lbs +- 1/2 should be sufficiently accurate for a damper, and this we could work to without trouble. Will you kindly let us have your further remarks so that we can report to Salters. BY.{R.W. Bailey - Chief Engineer} | ||