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).
Setscrew tests for securing gearboxes directly to aluminium crankcases.
| Identifier | ExFiles\Box 136\4\ scan0229 | |
| Date | 24th August 1938 | |
| 1153 To RHC.{R. H. Coverley - Production Engineer} from HPS{Horace Percy Smith - Experimental Factory Mgr}/W.Bell. c. to Rm.{William Robotham - Chief Engineer} o.{Mr Oldham} to Da.{Bernard Day - Chassis Design} o.{Mr Oldham} to RHC{R. H. Coverley - Production Engineer}/SB.{Mr Bull/Mr Bannister} HPS{Horace Percy Smith - Experimental Factory Mgr}/WB.{Mr Brazier/Mr Bell}1/CB.24.8.38. SET SCREW TESTS. To prove whether or not gear boxes could be secured to their crankcases by means of setscrews screwed directly into the aluminium and withstand service conditions (thus dispensing with inserts) a S/N .437 dia. X 18 T.P.I. setscrew, the length of the threaded portion of which was .650", was repeatedly screwed into and out of an A/C.403 block. A standard box spanner and a 6" tommy bar were used in the first series of tests, a "maltreatment" test being finally performed by using a 12" tommy bar. (1) 6" Tommy Bar. The setscrew was tightened down 60 times, and when examined, was found to be in reasonably good condition. Thus under these conditions, the setscrews will be perfectly safe up to 20 or 30 removals - the thread in the test block became slightly slack at this period of the test. (2) 12" Tommy Bar. This test was carried out firstly with the setscrew previously used during the 6" tommy bar tests and repeated with a new one. In both cases the threads in the test block had stripped by the time the screws were tightened down 3 times. The conclusion is that the steel or bronze insert can be omitted provided the lever used does not exceed 6". R.M.L. HPS{Horace Percy Smith - Experimental Factory Mgr}/W. Bell. | ||