The controlling force curves F, D, and B for a spring-controlled governor are shown in the figure, where r1 and r2 are any two radii of rotation.
The characteristics shown by the curves are
1
F - Stable; D - Isochronous; B - Unstable
2
F - Stable; D - Unstable; B - Isochronous
3
F - Unstable; D - Stable; B - Isochronous
4
F - Unstable; D - Isochronous; B - Stable