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).
Modifications to the rear axle and hub components for the Wraith III model.
| Identifier | ExFiles\Box 7\3\ X 602 Axle Rear-page39 | |
| Date | 15th April 1937 | |
| SECRET. 002. BY C.E. De. Rm.{William Robotham - Chief Engineer} HPS.{Horace Percy Smith - Experimental Factory Mgr} V/AR. E/HDY.{William Hardy}1/HP.15.4.37. Rear Axle - Wraith III. We send herewith N.Sch.5115 showing modifications to some of the rear hub pieces to give access to the nuts which secure the axle tube nut locking plate. The principal modification consists in making the thread for the axle tube nut 1.687 diameter instead of 1.750 diameter as given on CW.1427. A reduced diameter is shown on our N.Sch.5059, but has not been shown in the detail drawing. Consequently, as the parts are detailed, it is not possible to use a standard box spanner on the locking plate nuts. The axle tube nut should be the same as regards the spanner slots as the Bentley nut GB.832. We suggest that the special studs for the locking plate should be replaced by standard studs. The counter-bores in the stud holes in the axle tube nut should be deleted in this case. We do not think that any special provision is necessary to prevent the studs from screwing out of the nut. Another standard stud will have to be added to the list with dimension "A" .050 shorter than for RB.{R. Bowen}200 the shortest 3-BA stud at present provided. Alternatively RB.{R. Bowen}200 can be used with a plain washer as well as a springwasher under the nut. For the sake of economising, we suggest that the external teeth of the driver and the teeth in the hub should be the same as are now on test on the Bentley, and shown by EX.25109 and EX.25105. The new Bentley driver tooth is .181 deep and the Wraith III as at present instructed .200 deep. The bore of the projections of the teeth in the hub must be larger for the Wraith than is shown on EX.25105 for the Bentley. The Bentley should be increased to agree. The material for the Wraith driver should be S/ZN. E/HDY.{William Hardy} | ||