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).
Continued analysis of governor weight and spring characteristics to achieve a desired advance curve.
| Identifier | WestWitteringFiles\H\March1922\ Scan43 | |
| Date | 1st August 1922 | |
| Contd. -5- EFC1/T27.8.22. governor weights, a range most nearly suited to giving the required characteristic of advance. To this end - Curve A is the characteristic of the advance required. Curve IV represents the curve ideally obtainable with a weak spring, represented by IV in the diagram, using the range of governor weight motion from 72.5 to 87.5° between speeds of 250 and 1500 R.P.M. Curve III shows this similarly using the range from 70° to 85°. Each of these corresponds to a range of 12° on the cam. It will be seen from this that the desired characteristic of advance can be more nearly obtained by getting the weights to move as nearly as possible to the 90° position. In the actual governor, however, even though we had the weights made rectangular and flattened, we could not get these nearer than the 73¼° position, and the best advance characteristic curve we could produce was one such as II, corresponding to a spring represented by straight line II on the diagram, only in this case, to get the best average, we allowed a cam advance of 15° between 250 and 1500 R.P.M., corresponding to an angular advance of the governor weights of 5/4 of this amount. The process is also reversible, i.e. starting with the desired characteristic, say curve A, the curve marked A on the diagram is derived afterwards from this and represents the law which a spring should have in order to give the desired characteristic over that particular range. That curve, of course, implies a spring whose rating increases | ||