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).
Blueprint detailing the mechanism of a preselector self-changing gear control system for synchromesh gears.
| Identifier | ExFiles\Box 136\4\ scan0190 | |
| Date | 1st October 1937 | |
| PRESELECTOR SELF-CHANGING CONTROL FOR SYNCHROMESH GEARS. Type FP.{F. Potts} Gears Self-selected - from Neutral to Top - during getaways. Reduced height of gearbox and no gear lever give lower floor and more roomy front compartment. Synchromesh unit for 3rd & 4th speeds. Layshaft Shift Fork Peg Cam Fixed Bar Gear Striking Lever flat To Clutch Pedal A partial turn of the Self-change Shaft lowers all the coupling pawls - the pawl of the preselected gear then engages its striking lever by falling on a step in its top arm. Coupling Pawls Selector Shaft Self-change Shaft Step By allowing the shaft to return - either slowly or quickly - the upward push of the pawl actuates the striking lever and so moves the shift fork for 3rd speed. Gear Striking Lever 3rd 4th Fixed Bar Shift Fork Peg Clutch Pedal PEDAL DOWN :- 1 to 2 - Clutch diseng'd.{John DeLooze - Company Secretary} 2 to 3 - Gear diseng'd and new gear prepared for engagement. PEDAL UP :- 3 to 2 - new gear eng'd.{John DeLooze - Company Secretary} 2 to 1 - Clutch eng'd.{John DeLooze - Company Secretary} The mechanism is arranged in units - each unit controlling two speeds, as in Fig. 4. The usual Shift Forks are mounted on a fixed bar and each fork is moved by means of a pivoted gear striking lever, which engages a peg on the shift fork. An eccentric or self-change shaft carries Coupling Pawls - one for each speed - and these couple the Striking Levers to the Self-change Shaft. A Selector Shaft, formed with flats, can be turned to allow any one pawl to be coupled to its striking lever - keeping the others uncoupled. The Self change shaft is formed with Cams which engage Pegs on the shift forks and put the latter in neutral in the first half of a gear change operation. See descriptive sheets for methods of operation. Flats Pawl Selector Shaft Self-change Shaft TWO-SPEED UNIT. The strong simple unit shown above controls 3rd and 4th speeds. Two units are required for 3-Sp.{Mr Spinney} and Rev. Two units and half unit for 4-Sp{Mr Spinney} and Rev. Any number of speeds - forward reverse or overdrive - can be controlled. Cam The Cam puts gears into neutral with ease and precision. Its upper wall is notched to lock the Peg in its different positions. Self-selection of the gears during a getaway makes the getaway easier quicker and safer. See descriptive sheets. From A.Alltree - Oct 1937. | ||