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).
Phantom III rear shock dampers, their design history, and potential future modifications.
| Identifier | ExFiles\Box 95\4\ scan0088 | |
| Date | 13th March 1937 | |
| W/S. Sg.{Arthur F. Sidgreaves - MD} c. Hc.Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} Da.{Bernard Day - Chassis Design}1/HP.13.3.37. Phantom III Rear Dampers. Replying to Sg.{Arthur F. Sidgreaves - MD}1/E.11.3.37, the shock dampers fitted to the rear of Phantom III are standard dampers in all respects. There has been no change in design since the Phantom II days, and these dampers are used on 25/30, Bentley, and Wraith. In 1931 we designed a double piston damper having the feature of no reversal of load on the main bearing, and "R" pointed out at the time that it had this feature. We believe extensive tests were made on it, but it was found to have defects not connected with the above point, but there is nothing fundamentally wrong with it, and it could be revived with these defects remedied if it were thought worth while. The Gordon Armstrong is a close copy of it in principle. We understand that Experimental still consider that manufacture and not design is at fault with the existing type of damper as made until recently. The non-reversal of load however is a fundamental principle which should enable the double piston type to be made with less accurate fits on the main bearings than the present type. We should like to point out that the shock dampers fitted to the present Phantom III and Wraith front suspension also have this principle of non-reversal of load on the operating mechanism. Should it be decided that wear of the main bearings is a possible cause of future trouble, in spite of the Experimental evidence, to the contrary; in the existing damper it is possible to try (1) hardened steel bushes on a hardened shaft (2) needle roller bearings (probably not very good for shock loads) and (3) a system of pressure lubricating the bearings from the damper cylinders, such as was done in a previous design. This might cause some difficulty with oil leaks, and call for modification to the design of gland. Rubber mounting the damper body to the frame would probably assist the elimination of small knocks. Da.{Bernard Day - Chassis Design} | ||