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 change mechanism, focusing on clutch operation, cam, peg, gear lock, and coupling pawls.
| Identifier | ExFiles\Box 136\4\ scan0188 | |
| Date | 26th October 1937 guessed | |
| -2- When a gear has been preselected the driver depresses the clutch pedal and the first half of this movement disengages the clutch and the second half disengages any gear then engaged and prepares the preselected gear for engagement - the Coupling Pawl engaging the Striking Lever as shown in Fig. 2. By letting the pedal come up (either slowly or quickly to suit the gear) the pressure of the compressed clutch springs first engages the gear and then the clutch - as indicated in Fig. 6. The clutch can be disengaged without disturbing the gear in use but if the pedal is depressed beyond the normal limit for clutch operation and the gear is partially disengaged the gear is pushed back into full engagement before the clutch can re-engage. A gear can be preselected without disturbing the one in use. By preselecting the gear slightly in advance of the actual change the latter is effected simply by depressing and releasing the clutch pedal - a single action gear change. Adjustment (See "Cam and Peg" below). Cam and Peg. The Cam and Peg are employed solely to put gears into neutral. It should be noted that the Cam is shaped to allow the Self-change Shaft to turn without disturbing the Peg during clutch operation. This allows the pedal to be directly coupled to the Self-change Shaft and a single adjustment on the coupling rod makes all the adjustment that is required. Gear Lock (Fig. 5) The upper wall of the Cam has three notches that lock the Peg (and the Shift Fork) in its different positions, providing a strong gear lock without adding extra parts. In addition the Forks have a second simple lock which allows only one Fork to be moved at any time. Coupling Pawls. Each Pawl is rounded at its end to give a rolling contact with the top arm of the Striking Lever. Note that the Pawl end moves across the arm's centre line and that the Pawl slides in the deep slot or flat in the Selector Shaft. | ||