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).
Report discussing crankshaft vibration, harmonics, and the comparison of a standard 20 HP engine with a model 1-G-1 fitted with a damper.
| Identifier | ExFiles\Box 25\3\ Scan244 | |
| Date | 22th April 1927 guessed | |
| contd :- -3- wheel of suitable proportions, is to split the 'master vibration' into two others, one at a higher and the other at a lower speed and therefore, if of such proportion to do this, would be of little use in an automobile engine. As however it is only called upon to deal with the higher harmonics which are considerable less vigorous than the 'master period' - see attached curve which is explained later - it is made of smaller proportions which while sufficiently active to oppose these, is itself insufficient to impose oscillations in the crankshaft. Reverting to the case of 1-G-1, it would seem that by suitably relating the stiffness of the driving springs and small inertia wheel of this damper and perhaps modifying or eliminating the damping of the friction plates we could obtain precisely the same effect as the Summers Balancer on the Buick. We are at present fitting up 1-G-1 with the object of further testing this damper. The chief point of interest when comparing the std. 20 HP. and 1-G-1 is that the latter has its master period at a higher speed. We have proved however that this is not due to the action of the damper but due to the difference in the inertia of the rigid mass at the front end of the crankshaft. Actually the crankshaft of 1-G-1 is more flexible than the std.product, hence the importance of mass at the front end of the crankshaft is clearly demonstrated. It was stated in a previous report that by removing the whole spring drive unit from the forward end of the std. 20 HP. shaft and motoring over the master period was raised from 3300 to 3750 r.p.m. or approx. as 1-G-1. contd :- | ||