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).
Experiments determining the reduction in torsional strength of a 20 HP crankshaft during machining operations.
| Identifier | WestWitteringFiles\R\2December1927-February1928\ Scan022 | |
| Date | 5th December 1927 | |
| Hs{Lord Ernest Hives - Chair}/Tsn/LG5.12.27. 20 HP. CRANKSHAFT TORSIONAL STRENGTH. -------------------------- The accompanying diagram shews the results of experiments to determine the reduction in strength that takes place in the principle machining operations from the forging to the finished shaft. From curve 1. to curve 2. there is a reduction in stiffness of 32.5% due to the removal of .175 off the journal diameters and facing one side of the webs slightly; 20-25% is probably due to the journals. Another .170 is removed from the journals between curves 3 and 4, but here the difference is only 7%. This apparent inconsistency is due to the fact which Carter's formula shews that the stiffness depends on the 3rd. and 4th. power of the principal dimensions. The same effect may be observed in the two stages in the reduction of the crankpin diameters. The actual percentage difference shewn here for the various alterations cannot therefore be always expected from other shafts owing to variations in circumstances. We propose very carefully analysing these results, and comparing the actual observed alterations in stiffness for each change in the dimensions with the predicted values of Carters formula. As far as we can see at present there appears to be good agreement between the two. Hs{Lord Ernest Hives - Chair}/Tsn. | ||