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).
The application of a servo spring to the clutch and the advantages of an overdrive gearbox.
| Identifier | ExFiles\Box 91\2\ scan0352 | |
| Date | 15th September 1937 | |
| 3. RM{William Robotham - Chief Engineer}/188.J/VS.{J. Vickers}15.9.37. The application of a servo spring to the clutch pedal was immediately acceptable and welcomed as a big improvement. It was noticed that the extreme lightness combined with the position of the foot with the increased travel pedal, made the control of the final engagement somewhat sensitive. In spite of this, the action was much preferred to standard. Further development is in progress to improve the final engagement. During the preliminary traffic running the car was tried by Sales in comparison with their trials car and the effect of the servo described as very pleasing, and very desirable. ------ Over drive Gear box. 15.E.S. The gears were good standard for silence, and did not deteriorate during the mileage. The overdrive was practically inaudible with the exception of a slight noise between 35 and 40 m.p.h. The side shaft was audible when the car was stationary. This trouble is not expected when more gears are available for selection. The advantages gained over the standard gear box were as follows - (a) Increased silence due to reduced engine speed. (b) Petrol consumption could be improved by 15%. (c) Higher maximum speed and general performance improved. (d) Lighter gear change owing to reduced torque on layshaft. (e) Less gear changing in hilly country and in traffic, as second gear proved to be a good compromise between the standard third and second speeds. (f) Life of engine bearings prolonged. (g) Lower water and oil temperatures. (h) Reduction of maximum engine revs allowed a higher speed fan drive to be used which improved low speed cooling. | ||