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Governor terms and governor versus flywheel

Short answer

A governor controls mean speed by regulating fuel; a flywheel reduces cyclic speed fluctuations by storing kinetic energy. Sensitiveness = (N2-N1)/Nmean. Stability: a single equilibrium radius per speed, increasing with speed. Isochronism: constant equilibrium speed for all radii (unstable). Hunting: oscillation from overcorrection. Effort: mean sleeve force for a given speed change; Power: effort × sleeve lift.

Differentiate between a governor and a flywheel. Explain the terms sensitiveness, stability, isochronism, hunting, effort and power of a governor.

Governor vs flywheel

PointGovernorFlywheel
FunctionControls the mean speed against load changes over a long periodReduces speed fluctuation within one cycle
ActionRegulates fuel or steam supplyStores and releases kinetic energy
Works onChanges of loadChanges of torque within a cycle
ControlActive, with a sleeve and a link to the throttlePassive, no control mechanism
Needed whenLoad varies widelyTorque varies during the cycle

Terms

  • Sensitiveness: A governor is sensitive if it responds to a small change of speed. It is measured as
Sensitiveness=N2−N1N=2(N2−N1)N1+N2\text{Sensitiveness} = \frac{N_2 - N_1}{N} = \frac{2(N_2 - N_1)}{N_1 + N_2}

where N1,N2N_1, N_2 are the minimum and maximum equilibrium speeds and NN is the mean speed.

  • Stability: A governor is stable if, for every speed in its working range, there is only one radius of the balls at which the sleeve is in equilibrium, and the ball radius increases with speed.
  • Isochronism: The limiting case of a governor whose equilibrium speed is the same for all radii of rotation of the balls. Its range of speed is zero, so it is infinitely sensitive, but it is unstable (the balls move to an extreme position).
  • Hunting: Continuous fluctuation of the engine speed above and below the mean caused by an over-sensitive governor: it overcorrects, the sleeve moves up and down, and the speed keeps oscillating.
  • Effort: The mean force exerted at the sleeve for a given fractional change of speed (e.g. 1%). It is the force that can be used to move the control mechanism.
  • Power: The work done at the sleeve for a given percentage change of speed; power == (mean effort) ×\times (lift of the sleeve).

✓ Answer checked by Claude Opus 5.5 (high effort)

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