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).
Technical memo comparing rear axle gear ratios and proposing modifications.
| Identifier | ExFiles\Box 123\3\ scan0012 | |
| Date | 14th July 1933 | |
| Copy note To BY.{R.W. Bailey - Chief Engineer} from Da.{Bernard Day - Chassis Design} c. Wor.{Arthur Wormald - General Works Manager} E.{Mr Elliott - Chief Engineer} Hs.{Lord Ernest Hives - Chair} Hdy.{William Hardy} Da.{Bernard Day - Chassis Design}1/HP.14.7.33. P.2. J.3. Rear Axle Ratio. We find that we cannot get into the existing J.3. Hypoid axle casing, a higher ratio than 3.072 = 14/43. In order to do this we need to reduce the crown wheel to 9"dia. The following are the resulting figures, with those for the existing Phantom and for Bensport placed below for comparison. | | Ratio | MPH at 3150. | Crown wheel dia. | D.P. | Stress lbs | Load per in. of face lbs. | |---|---|---|---|---|---|---| | P.2. J.3. | 14/43 = 3.072 | 91.5 | 9" | 4.775 | 132000 | 8380 | | P.2. | 11/41 = 3.072 | | 11.74 | 3.500 | 93000 | 7700 | | Bensport. | 10/41 4.1 | | 8.5 | 4.82 | 125500 | 6300 | We are rather afraid of the high load per in of face in this proposal, also of the D.P. By making a new centre casing and new side plates, a Hypoid gear of 14/43 = 3.072 ratio can be got in with a 10" crown wheel, in which the stress and load per inch of face are comparable with the present phantom 2, as follows:- | Ratio | MPH. at 3150. | Crown wheel dia. | D.P. | Stress lbs | Load per in of face/lbs. | |---|---|---|---|---|---| | 14/43 = 3.072 | 91.5 | 10 | 4.3 | 94500 | 7510. | We have shown this proposal on N. Sch. 3754, herewith. By also making a modification to the differential | ||