Alterations to the Wraith II Gearbox spline design for cost reduction and manufacturing practice.
| Identifier | ExFiles\Box 8\11\ 11-page050 | |
| Date | 30th December 1936 | |
| 1044 628 SECRET. BY. {R.W. Bailey - Chief Engineer} C.E. Da. {Bernard Day - Chassis Design} RHC. {R. H. Coverley - Production Engineer} Rm. {William Robotham - Chief Engineer} Ws.HPS {Horace Percy Smith - Experimental Factory Mgr} ? E {Mr Elliott - Chief Engineer} /HDY. {William Hardy} 1/HP.30.12.36. Wraith II Gearbox. We send herewith N.Sch. 4988 showing six splines for the 1st speed wheel instead of ten as shown by N.Sch. 4838. This alteration has been asked for by Mr Wakefield to reduce cost. We have also reverted to our normal practice of making the gear a fit on the bottoms of the splines. This is because we are informed that there is no extra cost in grinding the bottoms of the splines to a fine limit as compared with a coarse limit, as they are form ground at the same operation as the sides of the splines. As shown by N.Sch. 4838 there is clearance top and bottom as is commonly done in American practice, but this is apparently of no advantage to us. We also show the splines at the front end of the 3rd motion shaft similarly treated as regards the fit on bottom of the splines but with 10 splines as before, as we cannot afford to lose any area of contact in this case. It is not intended that these alterations should lay the parts for the first box which should proceed as at present designed if they have gone beyond the stage at which they can be altered. E {Mr Elliott - Chief Engineer} /HDY. {William Hardy} N.Sch.4988 herewith. | ||
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).