KEVOS® MAKEOS · Mechanics
Toggle Clamp Design (Cylinder, Toggle Angle and Clamping Force)
What clamping force will this cylinder-driven toggle give at its locking angle, at what angle is the required force reached, and are the links strong enough?
Design check of a symmetric toggle clamp driven by a pneumatic cylinder: cylinder push force from bore, pressure and efficiency (as the pneumatic cylinder force tool), the toggle output force and link force at the clamping angle (as the toggle joint tool), the angle at which the required clamping force is reached, the output travel left from that angle to straight, the input travel, and the link stress against your allowable.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Cylinder bore | mm | Bore of the pneumatic cylinder driving the toggle joint. |
| Air pressure | bar | Supply pressure. |
| Cylinder efficiency | % | Share of the theoretical force delivered after seal friction. |
| Toggle angle at clamping (from straight) | ° | Angle of each link from the straight (dead-centre) line when the clamp closes on the part. |
| Clamping force required | kN | Clamping force needed on the part. |
| Link length | mm | Length of each toggle link (pin to pin). |
| Link cross-section area | mm² | Smallest cross-section of a link. |
| Allowable link stress | MPa | Allowable stress of the link material (your design value). |
Method and formulas
- Cylinder force F = p × π D² ÷ 4 × efficiency (as the pneumatic cylinder force tool).
- Toggle output R = F ÷ (2 tan α); link force = F ÷ (2 sin α) (as the toggle joint tool).
- Angle for the required force α = tan⁻¹[F ÷ (2R_req)].
- Output travel from α to straight = 2L(1 − cos α); input travel = L sin α; link stress = link force ÷ area.
- Example: a 50 mm cylinder at 6 bar gives 6.0596 kN at 5°; the required 5 kN is reached at 6.0524°.
Limitations
- Rigid, frictionless links: near the straight position, elasticity and pin clearance set the real force.
- Symmetric toggle with equal links.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Design a pneumatic toggle clamp for a fixture
- Find the angle to set for a clamping force
- Check the links of a toggle press
Who it is for
- Fixture designers
- Automation engineers
- Machine designers
What you get
- Cylinder force
- Clamping and link forces at the angle
- Angle for the required force, travels and link stress
Interpreting the result
- Clamping force rises steeply as the links straighten, so small part-size changes alter the clamp force a lot.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 172–174. Topic reference; no source tables or recommended settings are reproduced.
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Open the Toggle Clamp Design (Cylinder, Toggle Angle and Clamping Force) calculator
