BIZOMAT MAKEOS · Power Transmission
Cone Clutch Engagement Check (Torque, Engaging Force, Slip Time, Heat)
Will this cone clutch carry the torque, what force engages it, how long does it slip to bring the load up to speed, and how hot does it get each engagement?
Check of a cone clutch starting a load: torque capacity from the axial holding force, friction and cone geometry and the force to engage it (as the cone clutch tool), the slip time to accelerate the load inertia against its load torque at the clutch torque (as the torque to accelerate a rotating load tool), the heat generated by slip in each engagement, the temperature rise of the cone, and the engagements per hour the cone can shed, against the required torque and your temperature limit.
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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 | Largest diameter of the friction cone. |
| Small diameter of cone face | mm | Smallest diameter of the friction cone. |
| Cone half-angle | ° | Half-angle of the cone. |
| 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 the clutch must carry once engaged, with service factor. |
| Load | ||
| Load inertia at the clutch | kg·m² | Moment of inertia of the driven load referred to the clutch shaft. |
| Driving speed | rpm | Speed of the driving side. |
| Load torque during start | N·m | Resisting torque of the load while it accelerates. |
| Heat | ||
| Mass of the cone that absorbs heat | kg | Mass of the cone or drum that soaks up the slip heat. |
| Specific heat of the cone | kJ/kg·K | Specific heat of that part. |
| Largest temperature rise per engagement | K | Largest temperature rise per engagement you accept. |
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 largest diameter of the conical friction surface, at the wide end of the contact band.
- 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.
What this means: Small diameter of cone face
- What it is
- The smallest diameter of the conical friction surface, at the narrow end of the contact band.
- 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.
- Get it right
- It must be smaller than the large diameter.
What this means: Cone half-angle
- What it is
- The angle between the cone face and the clutch axis, half the included angle of the cone.
- 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
- Torque capacity rises as the half-angle falls, because it is divided by sin α.
- Get it right
- Enter the half-angle, not the included angle of the cone.
What this means: Coefficient of friction
- What it is
- The friction coefficient of the lining against the mating cone, from the lining maker.
- 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 is proportional to the friction coefficient.
What this means: Axial holding force
- What it is
- The axial force pressing the cones together while engaged, normally supplied by the clutch spring.
- 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 is proportional to the holding force.
What this means: Required torque (with service factor)
- What it is
- The torque the clutch must carry once engaged, 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.
Load
What this means: Load inertia at the clutch
- What it is
- The mass moment of inertia of the driven load referred to the clutch shaft; reflect it through any gearing by the square of the speed ratio.
- Units and format
- Enter a number in kg·m²: kilogram square metres (mass moment of inertia). The form accepts 0.000001 kg·m² to 1000000 kg·m². Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.5 kg·m² as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Driving speed
- What it is
- The speed of the driving side of the clutch, which the load must be brought up to.
- 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 1000 rpm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Slip time rises in proportion to speed, and slip heat with its square.
What this means: Load torque during start
- What it is
- The torque the load resists with while it accelerates, such as friction or process load.
- Units and format
- Enter a number in N·m: newton-metres. The form accepts 0 N·m to 100000000 N·m. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 40 N·m as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- It must be less than the clutch torque, or the load never accelerates and the tool stops.
Heat
What this means: Mass of the cone that absorbs heat
- What it is
- The mass of the cone or drum that absorbs the slip heat during an engagement.
- Units and format
- Enter a number in kg: kilograms. The form accepts 0.000001 kg to 100000 kg. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 4 kg as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The temperature rise per engagement is inversely proportional to this mass.
What this means: Specific heat of the cone
- What it is
- The specific heat capacity of the cone material, from material data.
- Units and format
- Enter a number in kJ/kg·K: kilojoules per kilogram per kelvin. The form accepts 0.000001 kJ/kg·K to 5 kJ/kg·K. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.46 kJ/kg·K as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Enter kJ/kg·K, not J/kg·K: divide a value in joules by 1000.
What this means: Largest temperature rise per engagement
- What it is
- The largest temperature rise of the cone in one engagement that you accept.
- Units and format
- Enter a number in K: kelvin (a difference of 1 K equals 1 °C). The form accepts 0.000001 K to 1000 K. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 15 K as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
Method and formulas
- Torque capacity T = μ F (D_o + D_i) ÷ 4 ÷ sin α; engaging force = F (sin α + μ cos α) ÷ sin α (as the cone clutch tool).
- Slip time t = J ω ÷ (T − T_load) (as the torque to accelerate a rotating load tool, solved for time).
- Slip energy = T ω t ÷ 2 (the clutch slips at a falling relative speed); temperature rise = energy ÷ (m c).
- Example: the clutch carries 162.33 N·m with 3,264.2 N to engage; it slips 0.42803 s and heats 1.9772 K each start.
Limitations
- Constant friction coefficient and uniform wear; new linings bed in.
- All slip heat into the cone; repeated starts accumulate heat.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check a cone clutch for a heavier load
- Estimate clutch heating per start
- Size the spring or actuator that engages a clutch
Who it is for
- Design engineers
- Machine designers
- Maintenance engineers
What you get
- Torque capacity and engaging force
- Slip time and slip energy
- Temperature rise per engagement
Interpreting the result
- Heat per start equals the load’s kinetic energy plus the work against load torque: high-inertia loads need large cones.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 2446–2449, 176–181. 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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Open the Cone Clutch Engagement Check (Torque, Engaging Force, Slip Time, Heat) calculator