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).
Description of a clutch-pedal control system for semi-automatic gear changes.
| Identifier | ExFiles\Box 147\3\ scan0133 | |
| Date | 24th August 1938 guessed | |
| CLUTCH-PEDAL CONTROL. As all gear change operations are made in the same order (clutch out - gear out : gear in - clutch in) it simplifies matters and saves time to effect the whole job by one simple movement. There is no point in splitting clutch and gear operations into separate controls for gear changing, when the necessity for so doing is removed by eliminating the normal gear lever. Clutch-pedal control is a cheap amd reliable method of providing a single control for gear changing - without interfering with the normal use of the clutch at other times. As adapted to this semi-automatic gear control a short robust coupling connects the control shaft of the mechanism to the clutch pedal. This coupling is so arranged that it provides an 'interval' between clutch and gear operations, in each direction of the pedal movement, to allow clutch operation without disturbing the gear in use. A single accessible nut makes all necessary adjustments. The pedal has a normal extent of movement that allows the clutch to be used without disturbing the engaged gear, a small extension of this movement being provided to effect the disengagement of one gear and the engagement of another. The pressure of the clutch springs is utilised to engage the gears - before it functions to engage the clutch - and, as the pedal gives the driver a nice control of the spring force, the gears can be engaged as rapidly or as gradually as he desires; the whole operation of clutch and gear being almost as simple and easy as operating the clutch alone. Gears can be shifted whether the engine is running or not running - as with a normal gear lever. Very little development will be required to make clutch and gear change work together in complete harmony. Although ample pedal movement can be allowed for clutch operation it may be pointed out that if the pedal is pushed beyond this limit, and partially disengages the gear in use, the gear will be again fully engaged before the clutch re-engages. Strong inwardly projecting teeth, C1 C2, in the Cam (Fig 8a) ensure that a gear must either be fully engaged or in neutral before the clutch members can engage. NOTE. In comparing preselector control as used with a synchromesh gear and as used with a planetary gear it should be noted that the synchromesh arrangement has a lighter pedal operation and the pedal movement is exactly the same for each gear change. This removes two of the objections sometimes made against the planetary gear control. | ||