KEVOS® MAKEOS · Mechanics
Lever Force with Several Loads
What effort balances these loads on a lever, or how long must the effort arm be?
Balance of a lever about its fulcrum: the effort needed at a given arm to hold up to three loads at their distances, or the arm length needed for a given effort, with the mechanical advantage and the fulcrum reaction.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Solve for | choice | Find the effort or the effort-arm length. |
| Lever type | choice | Arrangement of fulcrum, loads and effort (sets the fulcrum reaction). |
| Effort arm (fulcrum to effort) | mm | Distance from the fulcrum to where the effort is applied. |
| Available effort (arm mode) | N | Effort available, when solving for the arm. |
| Loads (distance from the fulcrum; 0 = unused) | ||
| Load 1 | N | First load. |
| Distance 1 | mm | Its distance from the fulcrum. |
| Load 2 | N | Second load. |
| Distance 2 | mm | Its distance. |
| Load 3 | N | Third load. |
| Distance 3 | mm | Its distance. |
Method and formulas
- Moments about the fulcrum: F x = W₁a₁ + W₂a₂ + W₃a₃.
- F = Σ W a ÷ x, or x = Σ W a ÷ F.
- Fulcrum reaction: F + ΣW when the fulcrum is between effort and loads, otherwise the difference of the two.
- Example: 800 N at 100 mm with a 600 mm effort arm needs 133.33 N.
Limitations
- Rigid, weightless lever in static balance; add the lever’s own weight as a load at its centre of gravity.
- Pivot friction is neglected.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Size a hand lever or foot pedal
- Check a clamping or brake lever
- Find the counterweight arm for a balance lever
Who it is for
- Design engineers
- Mechanical engineers
- Maintenance fitters
What you get
- Effort or effort-arm length
- Mechanical advantage
- Fulcrum reaction
Interpreting the result
- A third-class lever always needs more effort than load; it trades force for movement.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 167–168. Topic reference; no source tables or recommended settings are reproduced.
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