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).
Faults in springs made by Firths and recommending new spring specifications.
| Identifier | ExFiles\Box 72\3\ scan0122 | |
| Date | 11th September 1924 | |
| y9410 To BY.{R.W. Bailey - Chief Engineer} & HS.{Lord Ernest Hives - Chair} from R.{Sir Henry Royce} c. to CJ. BJ. PN.{Mr Northey} Commander Briggs. ? SECRET. E.{Mr Elliott - Chief Engineer} A.{Mr Adams} C. 11 & 111. R1/M11.9.24. X. 8410 X. 9410 X. 2628 Springs as made by Firths ought to break because not only is :- (1) Their clip system hideous, but (2) There is not enough steel in the spring because the under plates are too few in number, and too thick. (3) There is too much clearance for bump, because too thin rubber buffer fitted. This was left to Derby and the spring makers. WW. now specifies and recommends (12½% stiffer) springs only to range from 1100 to 1250 lbs. - 4 sizes. Thus light fast cars should be stiffly sprung, and heavy slower cars lightly sprung. The depth of these springs will range from 3.16" to 3.47" respectively. Such springs will (if correctly graded) not have greater stress than 86,000 lbs. Maximum bump will be 2.4", rubber buffers 2¼" thick. To prevent lifting the car above normal there will be ½" negative camber at normal load. They will be fitted with the usual 4 Woodhead pattern clips. These will be situated further back than usual, as shewn on WW. drawing, (which gives all other particulars). If these particulars are incorrect and impractical, advise WW., with your modifications specified, and obtain sanction for experimental test. R.{Sir Henry Royce} | ||