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).
Fatigue test results for differential housing failures.
| Identifier | ExFiles\Box 92\5\ scan0067 | |
| Date | 13th June 1936 | |
| To E.{Mr Elliott - Chief Engineer} c. to Sg.{Arthur F. Sidgreaves - MD} c. to Wor.{Arthur Wormald - General Works Manager} c. to By.{R.W. Bailey - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} X302 Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}21/KW.13.6.36. Differential Housing Failures - Ph.III. As we proceed with fatigue tests on this part it becomes quite clear that the standard piece is never likely to fail on the 20/25, and it is rather a mystery how we obtained the failure with the correctly machined piece which was found in the Experimental Dept. Since the failure we have carried out the following tests :- (1) A dynamometer test, in which the axle gears failed owing to the severity of the conditions. Examination of the differential case showed that it was perfectly satisfactory. (2) Wohler fatigue tests. The incorrectly machined pieces which succeeded in running 4,000 miles on 22-0-V lasted 3 minutes, the standard piece lasted 1 hr. 55 mins. A standard piece without the holes drilled in it, which are provided to allow lubricant to enter the centre of the case, ran 10 hrs. 50 mins. (3) Additionally, we have the evidence that there was no failure on the first two 15,000 miles tests on the Ph.III, and 35-EX has run 15,000 miles without trouble. Summarising the results of our recent research, therefore - (1) It is not necessary to get alarmed about the differential housings fitted to Ph.III's, although the policy to change them is obviously correct. (2) From these results it hardly seems necessary to change any of the differential housings on the 20/25. (3) By modifying the lubrication holes in the parts at present in the course of machining, all this material could be utilised on the 20/25 with perfect safety. Att: Hs{Lord Ernest Hives - Chair}/WB.{Mr Brazier/Mr Bell}30/KW.11.6.36. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||