BIZOMAT MAKEOS · Mechanics
Wedge Force with Friction
What force drives this wedge under a load, and will it stay in place?
Force to drive and to withdraw a wedge that raises a guided load, with friction on both wedge faces, and the self-locking check.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Load on the wedge | N | Load the wedge supports or lifts, perpendicular to its base. |
| Wedge angle | ° | Angle between the two wedge faces (taper angle). |
| Coefficient of friction (both faces) | Friction coefficient for the wedge faces, assumed equal on both faces. |
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: Load on the wedge
- What it is
- The guided load the wedge lifts or supports, acting at right angles to the wedge’s base.
- 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 10000 N as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Driving and withdrawal forces rise in direct proportion.
- Get it right
- Use the load at right angles to the base, not the weight if the load acts at an angle.
What this means: Wedge angle
- What it is
- The taper angle of the wedge, between its sliding faces, from the drawing or by measurement.
- Units and format
- Enter a number in °: degrees of angle. The form accepts 0.1° to 45°. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 6° as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A larger angle raises the driving force and makes self-locking less likely.
- Get it right
- Use the angle between the two working faces in degrees.
What this means: Coefficient of friction (both faces)
- What it is
- The coefficient of friction between the wedge and the surfaces it slides on, assumed the same on both faces, from material and lubrication data or a test.
- Units and format
- Enter a plain number with no unit. The form accepts 0 to 1. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.15 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Higher friction raises the driving force and makes self-locking more likely.
- Get it right
- Use a conservative value; lubrication or vibration can lower it and release a self-locking wedge.
Method and formulas
- Friction angle φ = atan μ.
- Driving force P = W tan(α + 2φ).
- Withdrawal force P′ = W tan(2φ − α); if 2φ > α the wedge is self-locking.
- Example: a 6° wedge under 10000 N needs 4,257.4 N to drive and 1,955 N to withdraw.
Limitations
- Simple wedge with the load guided perpendicular to the base; guide friction is not included.
- Friction varies widely; vibration can release a nominally self-locking wedge.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Size wedge levelling mounts and jacks
- Check that a wedge or taper key stays in place
- Estimate force to remove a taper key
Who it is for
- Design engineers
- Maintenance engineers
- Machine builders
What you get
- Force to drive the wedge
- Force to withdraw it
- Self-locking or not
Interpreting the result
- Use a small wedge angle for fine adjustment and self-locking; it needs more travel.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 169–171. Topic reference; no source tables or recommended settings are reproduced.
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