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).
Compromise on front spring design, discussing stiffness, plate thickness, and testing.
| Identifier | ExFiles\Box 42\3\ Scan156 | |
| Date | 13th September 1924 | |
| X3854 To CJ. from R.{Sir Henry Royce} c. to BJ. BY.{R.W. Bailey - Chief Engineer} HS.{Lord Ernest Hives - Chair} EP.{G. Eric Platford - Chief Quality Engineer} DA.{Bernard Day - Chassis Design} PN.{Mr Northey} S E C R E T. R1/M13.9.24. E.{Mr Elliott - Chief Engineer} A.{Mr Adams} C. FRONT SPRINGS. X.9410 X.2838. I have compromised between Sales, BY's and our views in the following way :- So far as we can see front wheel brakes do not affect the case. BY's desire for increased stiffness is to improve the life of the top plate. Sales and myself want the most flexible spring possible for easy riding, and to protect the body-work, and the twist on the chassis. BY.{R.W. Bailey - Chief Engineer} stocking a series of 12½% stiffer springs from 1100 to 1400 lbs., say 7 strengths of the average normal camber, we can supply from this one stock, any stiffness from 12½% to 20%, as desired, by moving up one or two sizes for different rating. The normal camber will vary between zero and say .4" negative, when the more flexible spring is used. So that only one stock will be needed for both 12½% and 20%. Some slight modification in the packings and rubber buffers may be needed to keep the car and bump normal. I have re-suggested and insisted upon thinner lower plates so that these shall not break in any type. Woodheads have suggested thinner top plate .285" instead of .3125 which promises to be an improvement. Bump test says yes. So the 12½% spring with Woodhead top plate and my thinner lower plates should stand as well as previous 25% spring with all the plates thicker. The way to prove this is to send cars to France with both springs (except all lower plates thin). My idea is that it is too costly to test anything which is not what we consider best for adoption, hence I say wait until you have the right. We could send out springs of both stiffnesses, but both with .312 top plates, (w but thin under-plates as we are sure these are good) and send spare .285 top plates for replacement. R.{Sir Henry Royce} | ||