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).
Semi-automatic gear control mechanism.
| Identifier | ExFiles\Box 136\4\ scan0187 | |
| Date | 26th October 1937 guessed | |
| SEMI-AUTOMATIC GEAR CONTROL. Lower Floor. No Obstructive Gear Lever. Easy Changing. This mechanism is a simple robust construction, self-contained with the gearing, that provides a preselector form of control for change-speed gears of the synchromesh type. Any number of speeds - forward reverse or overdrive - can be controlled. The mechanism can be operated by vacuum hydraulic or electric means, controlled by a small lever on the steering column, but a simpler and cheaper method of operation is to make use of the clutch springs for the job of engaging the gears, as described under the heading "Clutch-Pedal Operation." Gears can be self-selected during a getaway. Lower Floor and Roomy Front Compartment. As shown in Fig. 1, by getting rid of the usual top members of a gearbox and of the gear lever a more roomy and comfortable front compartment, with a lower floor, can be provided. Strong Simple Mechanism. A glance at Fig. 3 will show how the gears are engaged. The pivoted Striking Lever can move the Shift Fork (and the gear member) to either left or right according to which end of the top arm is pushed. An Eccentric or Self-change Shaft (Figs 1 2 and 4) carries strong Coupling Pawls - one for each speed - and these Pawls couple the Striking Lever to the Self-change Shaft. A Selector Shaft, formed with deep flats, can be turned to allow any one pawl to be so coupled and keeps the others uncoupled, the Selector Shaft being controlled from a small preselector lever on the steering column. The Self-change Shaft is also formed with Cams (one for each Shift Fork) that coact with strong Pegs on the Shift Forks to put the latter in neutral in the first half of a gear change operation, the action being positive and effected with ease and precision. Clutch-Pedal Operation. This has much in its favour as it makes use of a force that is always available when the normal clutch pedal is fully depressed, the pressure of the compressed clutch springs being utilised to engage the gear before functioning to engage the clutch. The clutch pedal is coupled to the self-change shaft. | ||