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).
Car suspension behaviour, focusing on rear axle rebound, front bump stroke checks, and the development of shock dampers.
| Identifier | ExFiles\Box 95\3\ scan0061 | |
| Date | 31th January 1935 | |
| -3- bad bump without adversely affecting the normal riding. Checking the rear axle rebound violently tends to lift the rear axle off the ground. The rear wheels of the Buick car leave the road. For a rebound check to be effective the check must take place immediately the axle starts to move to rebound, when the rear spring load is considerable. Owing to the manner in which the front of the car dips, the rear axle scarcely moves towards the bump buffers over the bump. Bump Stroke Check at the Front. Our first object is to get the front wheels on to the ground, so that the spring load from the wheel will be on the road at the moment the impulse is given at the rear. For this we need at least 5" rebound wheel movement. When we have got 10" initial deflection front springs on a Ph.II we shall be able to measure the actual rebound movement used. It would then appear to be very useful to have our variable rating system, N.Sch.4177, which gives increased load on the wheel at full rebound. If we cannot arrive at a satisfactory result from the above, we shall prevent the oscillation of the car by means of shock dampers. We are preparing a type of shock damper for the front of the car which gives a very high load on the first bump stroke after a large rebound stroke. This should stop the front of the car from dipping. Such a damper would not come into operation until a rebound stroke of more than that found necessary for normal riding on American cars had been exceeded. It would therefore seem likely that it would not affect the normal riding. It may also be an advantage to connect the rear dampers so that they give a high rebound load for the first stroke after a large rebound on the front. Another bad feature which still needs a lot of attention on SpectreCodename for Phantom III is the incessant fidgetting and clatter experienced in the rear on indifferent road surfaces. Both the Cadillac and Buick are very good in this respect. We are first going to try putting rubber between the rear axle and the road springs. HS{Lord Ernest Hives - Chair}/I.A.Leslie. | ||