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).
Schematic and explanation of a semi-automatic, preselective gear control system for synchromesh gears.
| Identifier | ExFiles\Box 147\3\ scan0136 | |
| Date | 1st August 1938 | |
| SEMI-AUTOMATIC GEAR CONTROL for Synchromesh Gears All Gears Preselective - with optional Self-selection during Getaways. From A.{Mr Adams} Alltree. Type F.R LABELS: Synchromesh Unit for 2nd & 3rd speeds. Gear Striking Lever Shift Forks Peg Fixed Bar Layshaft Section through Gearbox. Rev. 1st 2nd 3rd Pegs L1 L2 R Control Layout for 3-sp.{Mr Spinney} & Rev Gear Coupling Pawls Selector Shaft Spring Cam Control Shaft To Preselector Lever Control Shaft Lever Diagram of Working:- Stop D Flat Coupling Pawl Control Lever Pawl D X1 Locking wall of Cam N C1 C2 8a 4-sp.{Mr Spinney} & Reverse. Top TEXT BLOCKS: Under Diagram 1: The gear Shift fork is moved by a peg on the fork. An upward push of lever L1 to the left. Note the simple...compactly they...To reduce height of... Under Diagram 2: The gear Shift Forks are mounted upon a single bar and each moved by means of a pivoted Gear Striking Lever which engages a peg on the fork. An upward push of R (Fig.2) will rock the left and move the shift fork to engage reverse. A push at 1, 2 or 3 engages the corresponding gear. Note the simple robust character of the levers and how compactly they can be arranged at one side of the gears to reduce height of gearbox. Under Diagram 3 & 4: Figs 3 & 4 show the simple construction employed to preselect and engage the gears. A Control Shaft carries Coupling Pawls - one for each speed - and these pawls couple the control shaft to the Gear Striking Levers. A Selector Shaft - formed with flats - can be turned to allow any one pawl to be coupled to its gear striking lever, keeping the other pawls uncoupled. The Control Shaft is also formed with Cams which engage the Pegs on the shift forks and put the latter in neutral in the first half of a gear change operation. See also Figs 5, 6 & 8. Preselection does not disturb the gear in use. Under Diagram 5: As shown above the Selector Shaft has been turned to preselect a gear - note position of flat. By moving the Control Shaft lever downwards - as in Fig. 6 - all the Coupling Pawls are lowered and the Pawl D of the preselected gear then engages its gear striking lever by falling on a step in its top arm. All gears are now in neutral and the preselected gear is ready for engagement. By moving the control shaft lever back to its first position the pawl D rocks the striking lever to engage 2nd speed. See also Fig. 7 and Fig. 8. Under Diagram 6 & 7: The Gear Striking Lever L2 can move the shift fork to right or left, according to which gear has been preselected. The angles of movement, indicated at X and X1, are arranged to suit requirements. Under Diagram 8: The Cam puts gears... into neutral - with ease in the first half of a gear change operation. The upper wall of the Cam is notched. This is to lock the Peg in its different positions. The Cam contour is formed to suit the movement that may be employed. A method of control that is described in ... sheets. Under Diagram 9: This simple robust mechanism can be employed to control any number of speeds - forward or reverse. The arrangement for a 4-sp.{Mr Spinney} & Rev. gear will be understood from the above figure. | ||