Tests on Bentley III rear spring bushes and concerns about their suitability.
| Identifier | ExFiles\Box 100\1\ scan0180 | |
| Date | 22th July 1938 | |
| Handwritten notes: A.F.M. ① What do the Americans do ② What stress is set up by increasing spring eye dia .025 Routing Information: To BX. from HPS {Horace Percy Smith - Experimental Factory Mgr} a. {Mr Adams} Da. {Bernard Day - Chassis Design} c. Rm. {William Robotham - Chief Engineer} cr. {Mr Cra’ster / Mr Chichester} De/Hay. 446 Typewritten text: BENTLEY III REAR SPRING BUSHES. We have carried out tests on a Bentley rear road spring assembled in accordance with FB.3851 and incorporating a knurled type bush FB.3845. It was found that a load of approximately one ton was required to insert the bush with an interference on the plain diameter of .010. The bore of the bush did not collapse under this load, but the diameter of the spring eye increased by approximately .025. As the bushes were pressed into complete road springs for use on the chassis they were not removed to ascertain the effect on the knurling, but we do not consider that the knurling has cut into the spring bore. The springs as supplied were fitted with oil tubes, and consequently when the bushes were pressed in and the spring eyes opened out the tubes were damaged. We understand that this tube was originally intended to be inserted after pressing the bush into position, and whilst it is not considered very practicable it is the only way in which the tube can be made to seal external leakages. In view of the above, we do not consider this type of bush with the present clearances to be suitable for fitment to future chassis owing to the danger of the spring eye failing. You will no doubt recollect that some weeks ago I discussed this matter with you and you agreed to consider a scheme similar to the present Wraith arrangement whereby the bushes are peened over. HPS. {Horace Percy Smith - Experimental Factory Mgr} | ||
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).