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).
Back axle ratio, associated transmission knock issues, and proposals for new gear ratios.
| Identifier | ExFiles\Box 49\1\ Scan250 | |
| Date | 29th December 1920 | |
| X.4299 To R.R. of America, Inc. From R.{Sir Henry Royce} (For the attention of OY.) c. to CJ. c. to Wor.{Arthur Wormald - General Works Manager} c. to Hy.{Tom Haldenby - Plant Engineer} c. to Hs.{Lord Ernest Hives - Chair} c. to EP.{G. Eric Platford - Chief Quality Engineer} R10/G29.12.20. X.3457 RE BACK AXLE RATIO. X.4174 X.4299 Regarding the back axle ratio, I am in receipt of your memo which says that we need not fear a small number of teeth in the bevel pinion. There are, however, several reasons for desiring to avoid a big ratio of gear because it shews up such defects as the knock due to the rise and fall of the back axle relative to the body of the car. Naturally this with a big back axle ratio will make a greater variation in the angular velocity in the transmission shafting. The higher ratios are only intended or needed for the heavier closed cars on the larger chassis, as these are less liable to have transmission knocks, and so will bear the increased ratio, because they are steadier. We are proposing, however, for all covered bodies, to go to the ratio of about 3.5 given by the 15 tooth pinion already tested. I should be glad, however, if you would arrange for the Gleason people to make us three sets of 14/52 which gives just over 3.7 ratio. We think that probably this gear would be going as far in a direction of the low geared axle, as may be found wise, because we feel sure that in addition to the knock in the Contd. | ||