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).
Assessment of a pre-selection device for synchromesh gearboxes designed by Alfred Herbert Limited.
| Identifier | ExFiles\Box 136\4\ scan0079 | |
| Date | 11th April 1934 | |
| To E.{Mr Elliott - Chief Engineer} from HDY.{William Hardy} c. Hs.{Lord Ernest Hives - Chair} By.{R.W. Bailey - Chief Engineer} GRY{Shadwell Grylls} See me HE Pre selection Device for Synchromesh Gearboxes by Alfred Herbert Limited March 1933. A hand lever actuates circular cam plates which are moved bodily by the depression of the clutch pedal towards fingers connected to the gears. The following points appear to have some bearing on the suitability of this scheme for our use. (1) The change of gear occurs during the downward movement of the clutch pedal and it is therefore necessary that the movement of the selecting lever should be completed before the pedal is depressed. In this respect the control differs from that of the Wilson box, the selecting lever of which may be moved any time before the pedal begins to return. (2) The work of synchromeshing the gears is done by the foot, and must be performed after the clutch is free, so that it will have to be done during a pedal travel of about 2" which will result in an appreciable increase of load on the clutch operation. (3) Every gear change must be accompanied by a full depression of the clutch pedal. (4) The reaction on the cam will be considerable and will necessitate rigid control rods or else a locking device on the cam itself. Summarising. The scheme seems to be practical but will give a heavier clutch pedal than normal and requires a full depression of the pedal. HDY.{William Hardy} | ||