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(Codename for 3 1/2-litre Bentley) 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(Codename for 3 1/2-litre Bentley). | 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 | ||
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).