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).
Results of belt drive experiments focusing on engine vibrations at various speeds.
| Identifier | WestWitteringFiles\P\2July1926-September1926\ Scan131 | |
| Date | 4th September 1926 guessed | |
| contd :- -4- BELT DRIVE EXPERIMENTS. The results shewed that the vibrations occurred at the same speeds and the one at 3350 r.p.m. was just as severe as when running under power. The vibration at 1600 r.p.m. was not noticeable. When driving the crankshaft alone, without the pistons and con. rods, we could not detect any vibration periods over the previous speed range. We have therefore derived the following information from the foregoing experiments :- (1) With the standard crankshaft, con. rods etc. and normally adjusted slipper wheels the most severe vibration is felt at 3350 r.p.m. (2) A second and third vibratory speed occurs at 1600 r.p.m. and 1100 r.p.m. respectively but the vibration is less severe. (3) With no slipper wheels, the vibrations occur at the same speeds but are more intense. (4) If the polar moment of inertia of the front end of the crankshaft is increased by bolting the slipper wheels tight the critical speed is lowered and the other vibratory speeds in proportion. (5) We get the high speed vibrations when the engine is driven by a belt and the cylinder head removed, apparently just as severe as when running under power, but the lower speed vibrations are not noticeable. (6) There are no vibrations with the crankshaft only. contd :- | ||