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 issues like 'tossing', 'jouncing', and 'tramping' on 4-wheel brake cars, and offering potential solutions.
| Identifier | ExFiles\Box 29\1\ Scan262 | |
| Date | 16th November 1926 | |
| To OY. from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to Hy.{Tom Haldenby - Plant Engineer} +457 Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}3/LG16.11.26. 43900 With reference to your complaints with regard to 'tossing' and jouncing' of front axles on 4-wheel brake cars; we are not familiar with the terms used. however we conclude that the trouble to which you refer causes the visible bobbing of the radiator cap on relatively smooth stretches. We should like to emphasise that the RR. shock absorbers are not designed to be used with single acting rear dampers, and if the rear of the car is undamped in one direction they will produce undesirable features in the suspension. With regard to 'tramping' of which you complain at 50 m.p.h. with the RR. dampers. Our impression is that these are as good as any damper we have tried for preventing this trouble. However, we have recently made rather an interesting discovery with regard to high speed wobbles, though we have not yet completely established its full significance. This is, that if the rotational moment of inertia of the wheel is increased the maximum amount, while the transverse moment of inertia of the axle is increased the minimum amount, the tendency of any car to wobble is greatly reduced. In plain language, adding peripheral weight to the wheel is a palliative for 'shimmy'. We do it by putting into a tyre, inner tubes of increased section weighing 10 lbs. instead of 4 lbs. only it is necessary to make sure that the inner tube is nicely made, or the last state of the car may be worse than the first. We estimate that you can make a 50% improvement in a slight wobbler by these means, and should be interested to hear the result, if you make the test. For the RR. hydraulic gland, try a piece of asbestos yarn about 3/16 dia. wrapped three times round the shaft and then put under the spring pressure. The yarn should be quite dry when inserted. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||