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).
Comparison of plate thickness and build quality between Woodhead and Firth supplied Bentley road springs.
| Identifier | ExFiles\Box 87\4\ scan0034 | |
| Date | 25th May 1934 | |
| Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} X246 Hs{Lord Ernest Hives - Chair}/PD.14/KW.25.5.34. Distortion of Bentley Road Springs. We have carefully checked over several samples of Woodhead Bentley front springs and find that the 650 lbs. type, consisting of 8 plates, are of the same thickness throughout; i.e., .220" to .225". The Firth 650 lbs. type is made up of 9 plates. Below is a table of plate sizes :- Top .232 to .235" 2 .217 to .220" 3 .217 to .220" 4 .210 to .210" 5 .206 to .208" 6 .206 to .208" 7 .195 to .197" 8 .190 to .192" 9 .190 to .192" The Firth 25 HP. front spring is also made up of 9 plates in the following order :- Top .225 2 .207 3 .204 4 .195 5 .195 6 .195 7 .190 8 .185 9 .185 From comparisons made with Woodhead and Firth springs it is obvious that we are receiving Firth's springs in better condition than Woodhead's. Taking the bedding of the leaves for example, with Woodhead springs, both front and rear, spaces can be seen between the leaves; on Firth's the leaves are a far better fit. We also receive Woodhead springs into the Works built up dry; Firth's arrive oiled. Hs{Lord Ernest Hives - Chair}/F.Dodd. | ||