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 the gear disengagement, engagement, and the self-change spring mechanism.
| Identifier | ExFiles\Box 136\4\ scan0133 | |
| Date | 9th February 1937 guessed | |
| -2- Disengaging the Gears. It is of first importance that the disengaging of the gears, and putting them into correct neutral position, should be effected by positive means. This is obtained by the coaction of a strong peg on the striking lever and a triangular cam, of easy contour and robust form, in the self-change shaft. When the clutch pedal is depressed for a gear change the resulting partial turn of the self-change shaft ensures that any gear then engaged is definitely put into neutral position, as a preliminary step towards engaging the next gear. Easy Gear Engagement. By putting the gears into neutral by the positive action described above, the self-change spring has then only to shift the gear member from neutral into engagement - a short traverse that is favourable to a rapid and quiet gear engagement. The Self-change Spring. The spring required with this mechanism is of very different strength to the springs required in self-changing gears of the epicyclic type. In considering this detail of the mechanism it should first be noticed that the pawls are moved quite a short distance, the eccentric pin shown to the right of the sketches having its centre very near to the shaft axis. In consequence the spring force is applied through a big leverage and this allows the use of a comparatively light spring which is, in turn, compressed through favourable leverages from the clutch pedal. To some extent the self-change spring is assisted by the clutch spring. It should also be noted that the self-change spring has to move the gear member only from neutral into engage-ment - another point in favour of the light spring. Although a spring has much in its favour, and makes a self-contained gearbox, other means - such as vacuum cylinders etc., - can be employed to operate the mechanism. | ||