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).
Suspension design, comparing American and English road conditions, and analyzing anti-rolling features of different chassis.
| Identifier | ExFiles\Box 173\3\ img125 | |
| Date | 16th April 1934 | |
| - 2 - K.1/HP.16.4.34. ----------------- we former as/well know being highly cambered, narrow and very winding, while the latter are non cambered, broad and straight. American road surfaces have always called for low rating springing and the question of excessive rolling has not arisen. We will agree that the tests made up-to-date are altogether too short to be conclusive but we think this point requires watching in the application of independent suspension and low rating springing for English conditions. In this respect in particular we shall be very interested to observe the results obtained with the Cadillac when this car becomes available. Naturally the front suspension is only contributary as regards the lateral control of the car but with stiffer frames and more even weight distribution its share in this duty approaches that of the rear suspension and it should be advantageous to raise the base from which the car rolls as near to the centre of gravity of the sprung weight as possible contingent on not calling for too much sacrifice in respect to other features. In respect to the rear axle the road springs should be as far apart and as high up as possible, but not of course exceeding in height the centre of gravity. Unfortunately with the present scheme of construction using a wide chassis frame, these two factors of width and height are antagonistic since the springs are forced downwards by the frame. In the SpectreCodename for Phantom III we have brought up the rear road spring position well above that of J.111 chassis both for reasons of anti-rolling and increased ground clearance by special design. With regard to the rolling of front suspensions, there is little to choose between the Cadillac, the Dubonnet and the RR. scheme, but the first named has some small measure of superiority as its rolling base is slightly above the ground whereas the other two are definitely at ground level and moreover the Cadillac rolling base can be raised still higher by altering the linkage and accepting a larger measure of gyrostatic reaction from the road wheels. | ||