Redesign and lightening of the 20 HP rear axle, including reducing the driving shaft diameter.
| Identifier | WestWitteringFiles\C\June1919\ Scan19 | |
| Date | 4th June 1919 | |
| To DA. {Bernard Day - Chassis Design} from E. {Mr Elliott - Chief Engineer} Copy to GJ. " " HN {F. C. Honeyman - Retail orders} " " EH " " EFC. {E. Fowler Clarke - Electrical Engineer} ORIGINAL. RE 20 H.P. REAR AXLE. It will be remembered that when the bevel box for the 20 H.P. rear axle was designed, the central portion was based on using a driving shaft to the road wheels, having a castellation of 1.25" diameter. It was known at the time that this diameter was somewhat large in proportion to the remainder of the axle, and it has since been found in dealing with the rear hubs that it will be necessary to reduce these castellations. We accordingly attach drawing No. LeC.1099 shewing the rear hub arranged for a driving shaft having castellations of 1.125" diameter, which diameter is strictly pro rata with the big car, using a reducing ratio of .75 scale. Would you please, in accordance with Mr. Royce's wishes, alter the design of the pieces local to the driving shafts in the bevel box to suit the smaller driving shaft. This will have the beneficial effect of lightening the axle. It is expected that we should be able to use smaller ball bearings for the differential cage. We attach also a sketch LeC.1100, the object of which is to give you some idea of the construction that is to be employed in securing the tie rod, the torque tube supports, and the shock damper attachment, and also to shew you what provision has been made for jacking up the rear axle. We will send you later a scheme incorporating these features. Referring again to drawing No.LeC.1099, the hub cap shewn thereon should be copied as far as possible for the front (Contd.) | ||
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).