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).
Results of a series of vehicle impact tests.
| Identifier | ExFiles\Box 153\1\ scan0303 | |
| Date | 16th May 1939 | |
| -3- Test 12. 13 m.p.h impact. Rocking shaft twisted very slightly, approx. 2°, bearing tracks in roller follower indented. No further damage. Test 13. 15 m.p.h. impact. Car mounted bank for 15 ft. and could not be removed under own power. No further damage. The earth bank was then reinforced by placing the ½ ton block in front of it. This proved to be a very rigid obstacle. In every case the chassis stopped dead, and rebounded about 6 ft. Test 14. 10 m.p.h. impact. Rocking shaft twist increased to estimated amount of 15°. Some rollers inside roller follower apparently crushed. No further chassis damage. Test 15. 12 m.p.h. impact. Chassis badly aimed with result that frame extension also hit block. Frame bent. No further damage to steering mechanism. Test 16. 13 m.p.h. impact. Front suspension extensively damaged and chassis unfit for further tests. No additional twist in rocking shaft. The steering gear has not yet been dismantled after the last 5 tests so we do not yet know the exact amount of twist or the maximum side steering tube load. The above tests have proved the following points:- (a) In order to twist the rocking shaft without crushing the 3/16" dia. rollers, the parts of the steering gear must not rotate while the load is applied. It is only under this condition that the 3/16" rollers can embed themselves in their tracks and relieve themselves of excessive stress. If rotation occurs, as in Tests 1, 2, and 3 the rollers or balls crush before the shaft twists. This implies that rocking shafts can only be twisted by impact resulting from something in the nature of an accident. | ||