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).
Potential backlash issue and fitting error in the rear axle of a Phantom III.
Identifier | ExFiles\Box 91\2\ scan0117 | |
Date | 13th July 1937 | |
300a. To Rm.{William Robotham - Chief Engineer} from HPS.{Horace Percy Smith - Experimental Factory Mgr} HPS.{Horace Percy Smith - Experimental Factory Mgr}5/VS.{J. Vickers}13.7.37. 32-EX. PHANTOM III. Rear Axle. Referring to Rm{William Robotham - Chief Engineer}/IMW.{Ivan M. Waller - Head of Chateauroux}4/JAB.10.7.37. After careful investigation of shop practice, with particular reference to the fitting of keys and the assembly and inspection of the axle in question, we should be very reluctant to agree that the backlash developed on test can possibly be attributed to a fitting error, as might be assumed from the above memo. Apart from the fact that every axle, before and after assembly, is most carefully scrutinised by an independent inspector before being passed for test, the fitting of driving flange keys is, and always has been, considered one of the most important jobs on an axle. It is understandable that in the circumstances a tester would jump to the obvious conclusion that movement of the flange was due to slackness in assembly, but had a little more time been wasted in carrying out a thorough examination of the parts as dismantled, it is quite possible that something useful might, after all, have been learnt as a result of the failure. The fundamental principle when fitting a key of any description is to obtain a really tight fit in the shaft, and one cannot conceive that the pinion and flange in question can possibly have been assembled with .012 slackness as suggested. It is far more likely that movement developed due to weakening the coupling by removal of the flange to a point remote from the driving taper in order to accommodate the Hardy Spicer propeller shaft (see sketch below), and it would certainly be advisable to observe very closely the behaviour of the assembly during the remainder of the test. G8539 AS ON 32 EX. G83893 (STD). HPS.{Horace Percy Smith - Experimental Factory Mgr} | ||