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).
Gearbox problems and the preliminary design of an epicyclic gearbox.
| Identifier | WestWitteringFiles\U\2January1930-September1930\ Scan068 | |
| Date | 12th April 1930 | |
| R.{Sir Henry Royce} FROM DA{Bernard Day - Chassis Design}/HDY.{William Hardy} C. to SG.{Arthur F. Sidgreaves - MD} RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} C. to BY.{R.W. Bailey - Chief Engineer} HS.{Lord Ernest Hives - Chair} DA{Bernard Day - Chassis Design}/HDY{William Hardy}1/M12.4.30. X 7310 X 5310 X 523 ORIGINAL GEARBOX PROBLEM. In reply to R1/M1.4.30. we have been making preliminary designs for the full epicyclic gear as instructed in R2/M10.2.30., and have also been investigating the problem generally. We are not aware of any solution of the problem which is as promising as the full epicyclic box. The pre-selecting lever and clutch pedal control as used by Armstrong-Siddeley has a rather heavy clutch pedal load and a varying position of the clutch pedal when in engagement according to which gear is in use. The latter feature is not favourable to good control. The Salerni coupling parts are now being made for FAC. 7., and a trial should be possible in about weeks time. DESIGN OF RR. EPICYCLIC GEARBOX. We give below some remarks about the preliminary design work which we have done so far. GEARBOX TRAINS - 1st. & 2nd. SPEEDS. No difficulty is presented by these trains. When in 3rd. speed the pitch velocities are about one quarter of those of our present gears, and the planet RPM. about half engine speed. THIRD SPEED. It does not appear to be practicable to obtain a sufficiently high 3rd. speed with a 3rd. accelerating train of the simple type with the sun driven. Assuming our present ratios of 3rd. .740, 2nd. .500, and 1st. .290, the 3rd. speed train must have a ratio of .500. If a limit is put to the planet speed at 1.5 times engine speed, the ratio of this train is .350. If also the 1st. and 2nd. are raised to .350 and .570, the 3rd. becomes .725. We have also investigated the following methods of obtaining the necessary ratio:- (1) | ||