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).
Report comparing the slipping torques of a standard taper fit versus a parallel interference fit for the Wraith distributor drive.
| Identifier | ExFiles\Box 168\3\ img197 | |
| Date | 8th June 1939 | |
| To: [redacted] from HPS{Horace Percy Smith - Experimental Factory Mgr}/Bl. c. to Rm.{William Robotham - Chief Engineer} cc to [redacted] cc to [redacted] CHILDS HPS{Horace Percy Smith - Experimental Factory Mgr}/Bl.2/CB.8.6.39. WRAITH DISTRIBUTOR DRIVE. Spindle. DW.411. Fork. E.51718. To prove whether or not the tapers could be replaced by a parallel interference fit, the torques required to produce relative movement between the shaft and the fork, with both types of fitting, were checked statically - the diametral interference of the parallel type was given as .002". The slipping torques were :- Std. taper fit = 9 lb. ft. Parallel .002" diametral ) = 10 lb. ft. interference fit. ) Therefore providing the interference can be guaranteed, this method of assembly could be adopted to facilitate production, especially since it is understood that the two parts are finally locked by a taper pin. HPS{Horace Percy Smith - Experimental Factory Mgr}/W.Bell. | ||