BIZOMAT MAKEOS · Power Transmission
Cone Clutch Torque and Engaging Force
How much torque can this cone clutch carry, and what force engages it?
Torque capacity of a cone clutch by the uniform-wear assumption, the axial force to hold it engaged, and the higher force needed during engagement.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Large diameter of cone face | mm | Outer (large) diameter of the friction surface. |
| Small diameter of cone face | mm | Inner (small) diameter of the friction surface. |
| Cone half-angle | ° | Half-angle of the cone from its axis (often 8–15°; below about 8° the cone tends to stick). |
| Coefficient of friction | Friction coefficient of the lining. | |
| Axial holding force | N | Axial force holding the clutch engaged (spring force). |
| Required torque (with service factor) | N·m | Torque to transmit, multiplied by your service factor. |
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: Large diameter of cone face
- What it is
- The larger diameter of the conical friction surface, at its wide end.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 100000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 200 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A larger diameter raises torque capacity.
- Get it right
- Measure on the friction lining, not the outside of the clutch housing.
What this means: Small diameter of cone face
- What it is
- The smaller diameter of the conical friction surface, at its narrow end.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 100000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 160 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A larger small diameter raises torque capacity.
- Get it right
- It must be less than the large diameter.
What this means: Cone half-angle
- What it is
- The angle between the cone surface and the clutch axis, from the clutch drawing.
- Units and format
- Enter a number in °: degrees of angle. The form accepts 1° to 60°. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 12° as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A smaller angle raises torque capacity and raises the force needed to engage.
- Get it right
- This is the half-angle from the axis, not the included angle; very small angles tend to stick.
What this means: Coefficient of friction
- What it is
- The coefficient of friction between the cone lining and its mating surface, from the lining maker’s data.
- Units and format
- Enter a plain number with no unit. The form accepts 0.000001 to 2. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.25 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Torque capacity rises in direct proportion.
- Get it right
- Use a conservative value; oil contamination lowers it sharply.
What this means: Axial holding force
- What it is
- The axial force, usually from the clutch spring, that holds the cones together once engaged.
- Units and format
- Enter a number in N: newtons. The form accepts 0.000001 N or more. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1500 N as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Torque capacity and engaging force rise in direct proportion.
- Get it right
- Use the spring force at the worn-lining position if it falls with wear.
What this means: Required torque (with service factor)
- What it is
- The torque the clutch must transmit, already multiplied by your service factor.
- Units and format
- Enter a number in N·m: newton-metres. The form accepts 0 N·m or more. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 150 N·m as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Only moves the pass or fail line; capacity does not change.
- Get it right
- Apply the service factor before entering it.
Method and formulas
- T = μ F (D + d) ÷ (4 sin α).
- Engaging force (slipping in) = F (sin α + μ cos α) ÷ sin α.
- Margin = capacity ÷ required.
- Example: 1500 N on a 12° cone carries 162.33 N·m; engaging needs 3,264.2 N.
Limitations
- Uniform-wear assumption; new linings carry slightly more torque.
- Small cone angles may jam and need a release force.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Size a cone clutch or synchroniser
- Choose the cone angle
- Find spring force for a given torque
Who it is for
- Design engineers
- Maintenance engineers
- Machine builders
What you get
- Torque capacity (uniform wear)
- Force needed during engagement
- Margin over required torque
Interpreting the result
- Cone angles below about 8° tend to stick; above about 15° the axial force rises.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 2446–2449. Topic reference; no source tables or recommended settings are reproduced.
Learn the Concepts Behind This Tool
These BIZOMAT Library readings explain the method this tool uses, with worked examples.
Method explained here · BIZOMAT original book
Cone clutches
In Clutches and Brakes by the Numbers
What it covers: How a cone multiplies its axial force into friction torque, why engaging needs more force than holding, when a cone sticks, and how to check its torque, slip time and heat.
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