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).
Road spring failures, comparing on-road mileage tests with laboratory bump tests.
| Identifier | Morton\M3.4\ img016 | |
| Date | 5th September 1924 | |
| R.R. 493A (40 H) (SL 42 12-7-23). J.H., D.{John DeLooze - Company Secretary} -2- Expl. No. 9410 2628 REF: Hs{Lord Ernest Hives - Chair}1/LG5.9.24. EXPERIMENTAL REPORT. one pair ran 10,200 miles. During that time the top leaf on one spring broke after 6,900 miles - on the other front spring, the two lower leaves broke after 6,200 miles. It is very difficult to judge the life of road springs from one or two pairs run on the road - the conditions of running can vary considerably and we know from experience that with the same design of spring, one may last twice as long as another. We consider the bump test a very reliable test for judging the life of road springs because the conditions on these remain constant and we can test a large number of springs in a comparatively short time. Our bumping tests shew that the average life of the standard front springs (28 springs) is 12 hrs. The average life of (33 springs) 25% springs is 18 hrs. The average life of (3 springs) 12½% springs is 15 hrs. The spring failures that have occurred in France did not cause any difficulty in steering the car. in some cases the car has been driven 150 miles with a broken top plate, in order to get back home. Hs.{Lord Ernest Hives - Chair} | ||