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).
Letter detailing the methodology and results for crankshaft torsion tests.
| Identifier | ExFiles\Box 25\3\ Scan332 | |
| Date | 19th April 1928 | |
| Expl: Dept: X634 19th. April 1928. He/Tsnl/LG. Major E.C.Carter, Royal Aircraft Est., Farnborough. X2442 Dear Sir, CRANKSHAFT TORSION TESTS. In accordance with your telephone request, we are sending you a description of our method of twisting crankshafts, and some other information as well. The accompanying diagram (the extra copy is for you to send to Mr. Constant at Cambridge if required) shews the apparatus we use. The dial indicators read to .001" movement at 30" radius, and we take the twist in the shaft as the difference between the front and the rear readings. Points always lie very close indeed to a straight line, and we never have any difficulty in repeating tests with the same results. On the car crankshafts we usually go up to a maximum torque of 600 - 800 lbs.ft. and a twist of from one to two degrees; we take 8 or 10 readings at gradually increasing loads. All crankshafts are twisted in their crankcase, and usually with new or fairly tight bearings. When twisting the F.XI. crankshaft alone, without the reduction gear, the bearing clearances averaged .003" on the diameter. The maximum torque applied was about 800 lbs.ft. and the deflection about .600 degrees. We confirm the test results on this shaft as follows :- Test stiffness 78,400 lbs.ft/radian. Calculated value (by formula) 83,400 " " Ratio calc. value / test value = 1.062 or within 6% contd :- | ||