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).
Tests conducted to ascertain and eliminate bonnet movement and knocks on un-made roads.
| Identifier | ExFiles\Box 182\M19\ img206 | |
| Date | 18th June 1931 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Les.{Ivan A. Leslie} c. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. to E.{Mr Elliott - Chief Engineer} Da.{Bernard Day - Chassis Design} c. to By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Les.3/RT.18.6.31. 87260. 87005. P.II. BONNET MOVEMENT. We have carried out tests to ascertain the movement of the bonnet when driving over un-made roads at low speeds. The primary object has been to eliminate bonnet knocks. In order to get comparative results, tests have been done in the garage. The movement of the bonnet being measured when diagonal road wheels are raised from the ground. From our results it will be seen that diamond mounting (Fig.II) is considerably inferior to 4 engine feet (Fig.I), but is however very little worse than a Phantom I. (Fig.III) A central mounted radiator proved to be no advantage to reduce these figures, although when the bonnet touched the radiators, plenty of clearance could be made by pushing the radiators in the opposite direction to what the frame was twisted. Removing the springs each side of the central mounting did not effect an improvement. It seems for these tests it is necessary to locate the top of the radiator from the dash to ensure the movement of the radiator at its central mounting. This was effected by 2 stay tubes from brackets located to the dash just under the inner scuttle bolts meeting at the centre of the top of the radiator. The results are shown in (Fig.IV) and are actually an improvement against 4 engine feet. It must be remembered a central mounted radiator remains steady at jellying speeds owing to its inertia, we should therefore not expect excessive stress to either the radiator or the dash from these stay-tubes. We have tried two cars on the road in the later condition, one having rear engine feet disconnected, the other is 25-EX. with the latest diamond mounting etc. 2910/1. Both cars have been free from bonnet knocks and jellying as far as the radiator is concerned. Hs{Lord Ernest Hives - Chair}/Les.{Ivan A. Leslie} | ||