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).
Evaluation of vehicle noise levels at different speeds and a design analysis of the gearbox.
| Identifier | ExFiles\Box 136\4\ scan0108 | |
| Date | 1st November 1933 | |
| - sheet 2 - Silence. -------- The car was not sufficiently quiet generally to enable an accurate comparison to be made with our cars. My impression was that the silence was good except on the over-run, when the gear noise was objectionable. This indicates no doubt that gear noise on the drive was masked by exhaust noise etc. Idling. ------ Nothing objectionable noticed but too much traffic noise to judge this feature. Third Speed. ----------- Good on the drive but slightly noisy on the over-run. Second Speed. ------------ Slightly noisy on the drive but not objectionable. Over-run noisy. First Speed. ----------- Much more noisy than the other gears but not unduly noisy for straight tooth gears. Reverse Stop. ------------ Of the spring loaded lateral type of quite moderate strength. No tendency to get into reverse noticed on my short trial. Design. ------- The only detail information of the design which we have is from the Automobile Engineer of 1st November 1933. There is no apparent alteration except as regards the reverse stop which previously was by a catch on the box which had to be lifted as a separate operation. The principal features of design which are different from our practice are as follows:- (1) The casing is divided in a horizontal plane through the centre line of transmission. This gives a good external shape of the box from the point of view of the floorboards through which the box projects considerably, but is not the best method for maximum torsional strength or lightness of construction. (2) The gears are unground double helical and are solid blanks not lightened in any way. The layshaft pinion is rather badly overhung. The loose gears are mounted on needle roller bearings. | ||