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).
Analysis of a bump test on Woodhead springs, detailing failures and suggesting design improvements.
| Identifier | ExFiles\Box 42\3\ Scan165 | |
| Date | 16th October 1924 | |
| To HS.{Lord Ernest Hives - Chair} } To BY.{R.W. Bailey - Chief Engineer} } FROM R.{Sir Henry Royce} c. to CJ. DA.{Bernard Day - Chassis Design} Handwritten: Y3857 RE. BUMP TEST. X.1331 X.2628. We are very pleased to hear that the latest test shews that the Woodhead springs - all thin leaves - are lasting better than all previous springs. I notice that the braking is consistently near the centre of the spring. This would suggest that the lower plates were a little too long. If they are too long then the spring would bend excessively in the centre and therefore break in the centre. At the same time it would be preferable for the spring to be so designed because we should be using the bulk of the steel through the maximum range of stress, whereas if the under plates were too short, we should be bending the spring excessively at the ends, in which case the maximum quantity of steel would not be used to the maximum stress, and therefore the life of the spring would be less. Naturally it would be preferable that the spring broke in various places all over, and not in any one locality, and best of all we should prefer that the top plate was the last to break. We cannot however do any good by making the bottom plates break, as this would do us no good unless by allowing the bottom plates to break we could prevent the top plates breaking. I cannot see how we can do this. I do think however that we can move the position of the break in the top plate by varying the length of the lower leaves. This however should be done with considerable caution, but in the present case it would appear that the lower leaves should contd :- | ||