Project ForgeTheory of Machines
Governors & Flywheels
GATE 2021
Medium
The controlling force curves P, Q and R for a spring controlled governor are straight lines plotted against radius of rotation, where r1 and r2 are any two radii of rotation. The characteristics shown by the curves are
- AP – Unstable; Q – Stable; R – Isochronous
- P – Unstable; Q – Isochronous; R – Stable
- CP – Stable; Q – Isochronous; R – Unstable
- DP – Stable; Q – Unstable; R – Isochronous
Explanation
For a controlling-force line Fc = ar+b: if the line (extended backward) passes through the origin (b=0), the governor is isochronous; if it intersects the positive Fc-axis (b>0), it is unstable; if it intersects the positive r-axis (b<0), it is stable. Reading the three parallel lines' intercepts identifies P as unstable, Q as isochronous, and R as stable.
Source: GATE ME 2021 Session 2 (ME-2) (2021)
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