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).
Specifications and particulars of a four-speed synchromesh gearbox.
| Identifier | ExFiles\Box 126\5\ scan0154 | |
| Date | 8th March 1938 guessed | |
| - 7 - GEAR BOX. (SS.{S. Smith}93). Box is made in C.I. Cover for remote control gear is in Cast Aluminium. A four speed box is fitted with synchromesh to all speeds except first and reverse, RATIOS. Rear Axle First and Reverse 13.5 : 1 pinion 8 wheel 34 Second 7.9 : 1 Third 5.14 : 1 Top 4.25 : 1 All gears except 1st and Reverse, are Double Helical, (see sketch SS.{S. Smith}93) The main shaft is carried back in an aluminium extension piece in order to bring the forward universal joint of the propeller shaft sufficiently far back to clear the control cross bracing. Changes of 2nd, 3rd and top gears are obtained by synchronised dog clutches of the internal type. The internal toothed members slide on splines on the mainshaft. The dog member for top and third gear is on splines adjacent to the Constant mesh pinion, the second and first speed dog member being on splines at the rear end of the mainshaft which is carried at this end on a roller bearing in the main gear box casing. The layshaft consists of a plain spindle that runs through a bushed sleeve on which the layshaft wheels are mounted. PARTICULARS OF GEARS. 3.250 Centres. 1st. Speed Pinion ( 16 teeth .850 wide 8 D.P. 1st. Speed Wheel ( 36 " .750 " 8 D.P. 2nd. Speed Pinion ( 28 " 1.125 " 40º 13 D.P. 2nd. Speed Wheel ( 37 " 1.093 " " 13 D.P. 3rd. Speed Pinion ( 35 " 1.093 " " 13 D.P. 3rd. Speed Wheel ( 30 " 1.093 " " 13 D.P. Constant Mesh Pinion ( 27 " 1.125 " " 13 D.P. Constant Mesh Wheel ( 38 " .984 " " 13 D.P. Reverse Pinion 16 & 21 " 1.465 " 8 D.P. Reverse Wheel 36 " " 8 D.P. Further details of gearbox parts are available in Experimental Design Department. SS.{S. Smith}93. | ||