KEVOS® MAKEOS · Mechanics
Porter Governor Check (Heights, Sleeve Travel, Ball Radius, Centrifugal Force)
Over its control range, how far does this loaded fly-ball governor’s sleeve move, where do the balls run, and what centrifugal force do they carry?
Check of a loaded (Porter) or simple fly-ball governor with equal arms pivoted on the spindle axis: governor height at the working speed and the ends of the control range, sleeve height change and coefficient of speed variation (as the fly-ball governor tool), the ball radius from the arm length and height, and the centrifugal force on each ball at that radius (as the centrifugal force tool), checked against the sleeve travel you need and the largest speed variation you accept.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Mass of one ball | kg | Mass of each fly-ball. |
| Central load (0 = simple governor) | kg | Mass of the central (sleeve) load of a Porter governor; 0 for a simple Watt governor. |
| Governor speed | rpm | Normal running speed of the governor spindle. |
| Minimum speed of the control range | rpm | Lowest speed of the control range. |
| Maximum speed of the control range | rpm | Highest speed of the control range. |
| Arm length (pivot to ball centre) | mm | Length of each arm from its pivot on the axis to the ball centre. |
| Requirements | ||
| Least sleeve travel over the range | mm | Sleeve movement the control linkage needs over the range. |
| Largest coefficient of speed variation | Largest speed variation over mean speed you accept. | |
Method and formulas
- Height h = (g ÷ ω²) × (c + w) ÷ w at each speed; sleeve change = h_min − h_max; coefficient of speed variation = (n_max − n_min) ÷ mean (as the fly-ball governor tool).
- Ball radius r = √(L² − h²) for arms pivoted on the axis.
- Centrifugal force on a ball = w ω² r (as the centrifugal force tool).
- Example: at 200 rpm the governor stands 134.14 mm high with the balls at 148.35 mm radius carrying 130.14 N; the sleeve moves 26.962 mm over the range.
Limitations
- Frictionless, symmetric governor with arms pivoted on the axis.
- Steady speeds; hunting and damping are not covered.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check a mechanical governor for an engine or turbine
- Choose a central load for the speed range
- Teach governor sensitivity
Who it is for
- Mechanical engineers
- Restoration engineers
- Students
What you get
- Height at speed and over the range
- Sleeve travel and speed variation
- Ball radius and centrifugal force
Interpreting the result
- A heavier central load raises the speed the governor works at without changing its sensitivity.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 3453–3455, 187–190. Topic reference; no source tables or recommended settings are reproduced.
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Open the Porter Governor Check (Heights, Sleeve Travel, Ball Radius, Centrifugal Force) calculator
