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).
Comparing the frictional characteristics of Spectre and Bentley steering joints for potential use on Bentley and 25/30 HP chassis.
| Identifier | ExFiles\Box 95\1\ scan0288 | |
| Date | 23th June 1936 | |
| F.J.H. Please carry out necessary tests E.1/HP.236.36. Rm.{William Robotham - Chief Engineer} Hs.{Lord Ernest Hives - Chair} from E.{Mr Elliott - Chief Engineer} c. Wor.{Arthur Wormald - General Works Manager} Hs{Lord Ernest Hives - Chair}/Hdy.{William Hardy} re Steering Joints. In connection with the question of using the SpectreCodename for Phantom III type of steering joint on Bentley and 25/30 HP. chassis, it should be realised that the frictional characteristics of these joints are rather different. The friction effect in the case of the present Bentley joint occurs at the full diameter of the ball, and remains at its full value within the limits of the fit of the spring loaded pad in its housing at all times. In the case of the SpectreCodename for Phantom III type, the diameter of the friction surface is smaller than the ball diameter due to the method of applying the load, and only half of this friction remains constant at all times, the other half being dependent partially on the torsional rigidity of the spring and the place where rotational slip occurs, either between the ball and the pad, or between the pad and the spring. We should be glad if you would carry out some experiments plotting out the frictional characteristics of these two types of joints, so that we shall know what form of damping is relatively obtained. We may find that the SpectreCodename for Phantom III type of joint is only practicable with independent suspension in its present form. We are considering locking the spring loaded pad rotationally to the housing in future developments of this type of joint. We never anticipated having much steering trouble with the independent form of suspension, and the spring loaded effect on the SpectreCodename for Phantom III type of joint is mainly intended to keep the joint tight and free from vibration without having quite the same frictional effect as the type used for the conventional axle. E.{Mr Elliott - Chief Engineer} | ||