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).
Explanation of a diagram and curves detailing the dynamic couple exerted by governor weights for engine timing.
| Identifier | ExFiles\Box 51\5\ Scan218 | |
| Date | 27th March 1922 | |
| EFC {E. Fowler Clarke - Electrical Engineer} 1/T27.3.22. -2- Contd. be merely the 12° between 250 and 1500 R.P.M. and that any retard required below 250 R.P.M. would be done on the hand control. We have prepared a diagram and a sheet of curves for your information and with a view to making clear to you the difficulties of attaining, with the present design of mechanism, the type of advance characteristic required by the engine. It will be necessary to give a rather full explanation of the diagram and curves. The diagram shows in the first instance a family of curves, each of which is a curve for some definite speed, as labelled, of the dynamic couple exerted by the governor weights with varying angular position of governor. Along the bottom there are two scales, one of angular position of governor weights ranging from 45° to 90°, and the other of the corresponding angular advance of the cam, ranging from 0 to 36°. it having been ascertained by actual test that the ratio of angular motion is very nearly constant and as 5 to 4. The dynamic couple exerted by a body, pivoted in this manner about an axis at right angles to the axis of revolution of the system, varies for a given speed of rotation as the sine of twice the angle either from the horizontal or vertical position, and is therefore greatest at the 45° position, i.e. in the position in which the weights were originally designed to start off. Hence each member of the family of curves is half a sine curve falling to zero at 90°, but owing | ||