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).
Tests concerning reverse jaggers, axle torsional flexibility, and various methods for reducing pedal pressure.
| Identifier | ExFiles\Box 85\2\ scan0293 | |
| Date | 10th November 1936 | |
| -4- (5) Fitted wooden blocks between rear springs to cut out all spring movement. This improved reverse jaggers, making forward and reverse equally bad. This confirms that reason why reverse is worse than forward is because in one case the spring is being pushed against its shackle. The negative results obtained from the above tests lead to the conclusions that the exceptional torsional flexibility of the 1/2 shafts is the root of the trouble. We are accordingly about to try an axle which is about 4 1/2 times as stiff as standard. 2. Pedal Pressure There are vious ways of reducing this:- (a) VM.20. has a higher u than No.6. and permits 10% lighter springs. These are on 35-EX. (Rm.{William Robotham - Chief Engineer}31) (b) Design have now given us 20% more pedal travel. We shall probably not require all this to accommodate increased cushioning. The rest is available for lightening the pedal. (c) Vacuum servo assister. This is going on 38-EX., and also incorporates a scheme for greater separation. It is costly and not desirable. (d) Cam servo. We tried one of these (Rm.{William Robotham - Chief Engineer}69) which was designed to keep a constant pedal loading, this reducing the load in the fully down position by 8 lbs. Actually the gain was very little as the loading of the servo spring increased the friction of the pedal bearing. If more assistance is designed for, the snags are:- (1) Pedal becomes increasingly heavier as it is raised - an objectionable feature. (2) Large load on pedal bearing. (3) Unless cam tangential when pedal is up, setting alters as clutch wears. (4) Cam, owing to peculiar shape, becomes enormous. (e) Semi-centrifugal clutch of Long type. The attached print illustrates that this would be no good for Ph.III., where max. torque is developed at very low speed. No more than 15% saving would be expected at the most, at the expense of a very heavy continued | ||