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).
Design specifications for the Junior gearbox and axle, considering engine sizes and sales projections.
| Identifier | ExFiles\Box 136\2\ scan0132 | |
| Date | 5th August 1939 | |
| 1153 +1030 By.{R.W. Bailey - Chief Engineer} from Rm.{William Robotham - Chief Engineer} c. Da.{Bernard Day - Chassis Design} c. Da{Bernard Day - Chassis Design}/Hdy.{William Hardy} c. Da{Bernard Day - Chassis Design}/Ev.{Ivan Evernden - coachwork} c. Da{Bernard Day - Chassis Design}/Jnr.{Charles L. Jenner} Rm{William Robotham - Chief Engineer}11/R.5.8.39. JUNIOR GEARBOX. With reference to Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls}7/MH.{M. Huckerby}28.7.39., we are in favour of making the gearbox for the Junior Rationalised Range .71 of PD.477. This is shown in the memo to give a weight of 46.8 lbs. The reason we say this is because we believe that in the Junior range 90% of the cars sold will be 2-litres and below, and only 10% 2.8-litres. We consider it is more economical to make 10% of the Junior Range carry 30 lbs of extra gear-box than to make 90% carry 12 1/4 lbs of extra gearbox. Actually, of course, simple arithmetic shows that if this ratio of sales is correct we shall save three times as much material by using the small gearbox as we should if we designed it for 3-litres. With regard to the axle, we believe that it will be found that the difference between the design of the 2-litre and a 2 1/2-litre is so small that it is worth making it take the 2 1/2-litre torque. This wants confirming. If this is so, then the 2 1/2-litre 4-cylinder car becomes a 'Myth' with this engine and the Senior gearbox. Ev.{Ivan Evernden - coachwork} does not anticipate any difficulty in getting the Senior gearbox into the space available in the 'Myth'. One point on the 'Myth' which has got to be decided very quickly is whether we want a double or a single propeller shaft, and how much hypoid is required on the axle. If in any case, we have got to accept a tunnel when we drop the floor, then we think the extravagance of a double propeller shaft is not justified, in other words, we would just as soon have a tunnel which the passengers would notice and, therefore, avoid, than one which they will fall over because they cannot see it. As a matter of fact, we are doubtful whether it is good policy to have a tunnel at all on a Rolls-Royce product. Rm.{William Robotham - Chief Engineer} | ||