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 chassis design between the 20 HP and 40/50 models, focusing on factors affecting pitching.
| Identifier | ExFiles\Box 67a\2\ scan0081 | |
| Date | 21th December 1927 guessed | |
| -2- contd :- spare wheels are carried far out behind the rear axle. Therefore, quite apart from the unconventional front suspension, we should expect this car to ride well because we can see why it should be free from pitching. The 20 HP. car has unit engine and gearbox construction which removes the gearbox from the centre of the car forward. It has a Hotchkiss drive which eliminates the sphere and attendant cross members and torque rods from the centre of the chassis, it has the frame extended rearwards for the semi elliptic springs and the spare wheel carried at the rear. All these factors tend to reduce its susceptibility to 'pitching', when compared with the 40/50 which has the additional disadvantage that the weight of its rear springs is carried on the sprung portion of the chassis undesirably near the centre thereof. Actually, the fact that the 40/50 has a longer wheel base than the 20 HP. is a disadvantage for similar types of bodies. Briefly, as the wheel base of the modern car is more or less fixed at XXXXXXXXXX the moment, our endeavour is to increase the flywheel effect of the car in the pitching plane as far as possible for any given total weight. The means available for doing this are at the moment somewhat limited with the conventional chassis but they can be tabulated as follows :- contd :- | ||