BIZOMAT MAKEOS · Mechanics
Fly-ball (Porter) Governor Height and Sensitivity
At what height does this fly-ball governor run at this speed, and how sensitive is it?
Height of a loaded (Porter) or simple conical-pendulum fly-ball governor at a given speed, the sleeve movement between two speeds, and the coefficient of speed variation used to compare governor sensitiveness.
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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 one fly-ball. |
| Central load (0 = simple governor) | kg | Mass of the central sliding load on the spindle (Porter governor); 0 for an unloaded Watt governor. |
| Governor speed | rpm | Speed of the governor spindle. |
| Maximum speed of the control range | rpm | Highest speed within the governor’s range of action. |
| Minimum speed of the control range | rpm | Lowest speed within the range. |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Mass of one ball
- What it is
- The mass of one of the rotating fly-balls, one of the matched pair that swing outwards as the spindle speed rises.
- Units and format
- Enter a number in kg: kilograms. The form accepts 0.000001 kg to 10000 kg. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2 kg as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- With a central load, heavier balls reduce the factor (c + w) ÷ w and so lower the governor height; with no central load it has no effect.
What this means: Central load (0 = simple governor)
- What it is
- The mass of the central sliding weight that rides on the spindle and is lifted by the balls in a Porter governor; zero for a simple (Watt) conical-pendulum governor.
- Units and format
- Enter a number in kg: kilograms. The form accepts 0 kg to 100000 kg. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 10 kg as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The height rises in proportion to (c + w) ÷ w, so more central load raises the running height at a given speed.
- Get it right
- Include the mass of the sliding sleeve if it moves with the central load.
What this means: Governor speed
- What it is
- The speed of the governor spindle at which the governor height is wanted.
- Units and format
- Enter a number in rpm: revolutions per minute. The form accepts 0.000001 rpm to 100000 rpm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 200 rpm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The height falls with the square of speed: doubling the speed quarters it.
- Get it right
- Use the governor spindle speed, not the engine speed, when the governor is driven through gears or a belt.
What this means: Maximum speed of the control range
- What it is
- The highest spindle speed within the governor’s range of action. With the minimum speed it gives the sleeve movement and the coefficient of speed variation.
- Units and format
- Enter a number in rpm: revolutions per minute. The form accepts 0.000001 rpm to 100000 rpm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 210 rpm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Widening the gap between maximum and minimum speed increases the coefficient of speed variation and the sleeve movement.
What this means: Minimum speed of the control range
- What it is
- The lowest spindle speed within the range of action. It must be below the maximum speed; their difference divided by the mean speed is the coefficient of speed variation.
- Units and format
- Enter a number in rpm: revolutions per minute. The form accepts 0.000001 rpm to 100000 rpm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 190 rpm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
Method and formulas
- h = (g ÷ ω²) × (c + w) ÷ w — the handbook’s h = 2933 ÷ n² × (c + w) ÷ w in feet; c = 0 gives the simple pendulum governor.
- Coefficient of speed variation C = (M − M₁) ÷ m, with m the mean speed.
- Example: 2 kg balls with a 10 kg load run at a height of 134.14 mm at 200 rpm.
Limitations
- Arms pivoted on the spindle axis with equal arm and link lengths; friction is neglected.
- Spring-loaded (Hartnell) governors need a spring force balance instead.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check the sleeve travel of a centrifugal governor
- Compare loaded and simple governors for a speed range
- Restore or replicate a mechanical speed regulator
Who it is for
- Machine designers
- Maintenance engineers
- Automation engineers
What you get
- Governor height at the speed
- Sleeve height change across the range
- Coefficient of speed variation
Interpreting the result
- A larger central load raises the working speed for the same height and makes the governor usable at higher speeds.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 3453–3455. Topic reference; no source tables or recommended settings are reproduced.
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Open the Fly-ball (Porter) Governor Height and Sensitivity calculator