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).
Comparison of two proposed front suspension designs for the Wraith III, focusing on the coil springs and shock dampers.
| Identifier | ExFiles\Box 9\8\ 08-page06 | |
| Date | 22th March 1937 | |
| SECRET. 642 Sg.{Arthur F. Sidgreaves - MD} Hs.{Lord Ernest Hives - Chair} c. Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} Da.{Bernard Day - Chassis Design}4/HP.22.3.37. Wraith III - Front Suspension. Now that we have had the opportunity of examining more or less in detail both the types of front suspension proposed for Wraith III, since both have been practically completely designed, we think that we can form a more definite opinion than heretofore of their relative merits from our point of view. (1) The Coil Springs. The coil springs on any of these suspensions tend to become highly stressed. On the R.R. type, the springs are contained in an oil-filled reservoir, and are thus protected from weather, corrosion, and damage due to stones either flung at the coils or caught between them. The loads and deflections are purely axial, the steel being used to its best advantage. In the R.R. Buick type the springs are exposed, and can be filled with mud. Since they cannot be ground after coiling, hair cracks and other blemishes in the surface can be penetrated by moisture, and, therefore, the springs must be protected by enamelling or plating. The loads and deflections are not purely axial, the stress being correspondingly increased, though this increase is probably not excessive. They require rubber fabric seating to take this bending load. It is true that the position of the springs tends to enable the Buick type springs to be designed for lower main stresses than the R.R. but this is not fundamental. (2) The Shock Dampers. We suggest that the shock damper in the R.R. system is fundamentally of the simplest possible kind consisting as it does merely of a piston and valve system. As applying to the shock damper there are no operating levers, no connecting rods either rubber or lubricated ball end type, no rotating bearings, and in fact no external casing with separate mounting, since these are included in the spring containers. | ||