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).
Investigation into a broken American crankshaft, analysing its material properties and comparing its failure mode to a similar case.
| Identifier | ExFiles\Box 38\6\ Scan044 | |
| Date | 19th November 1918 | |
| X3381 EH. from EY. November 19.1918. PY3/P191118. RE AMERICAN CRANKSHAFT WHICH BROKE DURING EXPERIMENTAL RUNNING. I cabled for the test figures of crankshaft 1108. Mr Olley has replied giving the following particulars:- Analysis of Crank. Carbon .40% Nickel 1.25% Chromium 1.00% Test Figures. The shaft gave the following test results. Yield Point 63.4 tons. Maximum Stress. 68.7 Elongation 17% Red. in Area. 52% Brinell 311 Stanton figure 5350 blows. From the above figures it will be noticed that the steel was in quite a good condition and that the failure of the crank cannot apparently be ascribed to faulty steel. Mr Platford has had a crank returned out of B.Eagle.540 which, after running for over 200 hours broke in exactly the same manner as the American crank, that is, on number 5 journal from the crankpin, and taking in its path the screwed hole for the plug in both Webs and also passing through the oil hole in the journal - the two cracks for apparently identical. Mr Royce will remember that from our investigations at this end we demonstrated that the greatest variations of stress occurred in number 5 journal. We are leaving as much metal as possible on the flat end of the web and investigating whether we can use a smaller drill for drilling the oil hole. BY.{R.W. Bailey - Chief Engineer} | ||