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).
Crankshaft and crankcase vibration, comparing materials and summarising flywheel test results.
| Identifier | ExFiles\Box 14\2\ Scan064 | |
| Date | 29th November 1929 | |
| -13- vibration of crankshaft and crankcase will be much worse when the rods and pistons are present. It is easy then to understand the efforts of some firms, particularly the Americans, to suppress this vibration with massive cast iron crankcases. The latest Buick "Marquette" is an education in this respect. It has two horizontal webs along each side, F.XI type main bearing caps completely let in the crankcase (without horizontal through bolts however) and several very stiff ribs in each bearing web. Four balance weights are also used. Tests by Hl. shew that our standard cylinder iron has a Young's Modulus 50% higher than T.50.L. alloy. We can see then that the degree of support given to the main bearings in our engine is nothing approaching that in some other cars. If two crankcases were cast to the same patterns, the aluminium one would be two thirds the stiffness of the cast iron one. SECTION 2. FLYWHEEL. Resume of test results :- (1) The flywheel vibrates, even with a plain parallel shaft. Removing the overhanging portion very nearly cures the vibration. (2) With the crankshaft fitted, removing the flywheel removes a whole lot of booming periods. (3) From watching the flywheel it can be seen that there | ||