KEVOS® MAKEOS · Pneumatics
Hinged Flap Cylinder Check (Force Through the Swing, Stroke, Cylinder Size)
For a hinged flap, lid or door raised by a pneumatic cylinder, what force does the cylinder need through the swing, what stroke, and is my cylinder big enough?
Check of a cylinder raising a hinged flap: the moment of the flap weight about the hinge at each angle through the swing, the cylinder length and its moment arm about the hinge from the base and rod-end pivot positions, the cylinder force needed at each angle and its largest value, the stroke needed, then the extend force, load ratio and smallest bore for that force at the supply pressure (as the pneumatic cylinder force tool), against your load ratio limit and the cylinder stroke.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Flap mass | kg | Mass of the flap or lid. |
| Hinge to flap centre of gravity | mm | Distance from the hinge to the flap’s centre of gravity, measured along the flap. |
| Swing (from horizontal) | ° | Angle the flap swings through, from closed (horizontal). |
| Cylinder pivots (hinge at 0, 0; flap along +X when closed) | ||
| Hinge to rod-end pivot along the flap | mm | Distance from the hinge to the cylinder rod-end pivot, along the flap. |
| Base pivot X | mm | Horizontal position of the cylinder base pivot from the hinge. |
| Base pivot Y | mm | Vertical position of the base pivot (negative below the hinge). |
| Cylinder | ||
| Bore | mm | Cylinder bore. |
| Rod diameter | mm | Rod diameter. |
| Supply pressure (gauge) | bar | Supply pressure. |
| Efficiency (seal friction) | % | Share of the theoretical force left after seal friction. |
| Largest load ratio | % | Largest share of the theoretical force the load may use (lower for smooth, fast motion). |
| Cylinder stroke | mm | Stroke of the cylinder you have. |
Method and formulas
- Weight moment about the hinge = m g r_g cos θ; rod end at (r_c cos θ, r_c sin θ).
- Cylinder line from the base pivot to the rod end; moment arm = perpendicular distance from the hinge; force needed = moment ÷ arm, the largest over the swing.
- Extend force = p A η; load ratio = force needed ÷ p A; smallest bore = √(4F ÷ (π p × ratio)) (as the pneumatic cylinder force tool).
- Example: up to 1,377.5 N needed at 25°; stroke 156.84 mm; load ratio 73.648%.
Limitations
- Slow lift; acceleration and cushioning loads are extra.
- Flap centre of gravity on the line from the hinge through the rod end.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Size a cylinder to lift a machine guard or hopper lid
- Choose cylinder pivot positions
- Check a flap cylinder after adding weight
Who it is for
- Machine designers
- Automation engineers
- Maintenance engineers
What you get
- Force needed through the swing
- Cylinder lengths and stroke
- Cylinder force, load ratio and smallest bore
Interpreting the result
- Moving the rod end further from the hinge cuts the force but lengthens the stroke in proportion.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 3032–3041, 153–163. Topic reference; no source tables or recommended settings are reproduced.
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Open the Hinged Flap Cylinder Check (Force Through the Swing, Stroke, Cylinder Size) calculator
