BIZOMAT MAKEOS · Mechanics
Machine Levelling Wedge Check (Drive Force, Self-Locking, Travel)
Can these levelling wedges lift my machine with the force I can apply, will they stay put under load, and is there enough wedge travel for the height adjustment?
Check of wedge-type levelling elements under a machine: load on the most heavily loaded wedge from the machine mass and its share, the force to drive the wedge under the load and the force to withdraw it, with friction on both faces (as the wedge force tool), whether the wedge is self-locking, the wedge travel needed for the height adjustment and the lift per millimetre of travel, against the drive force and travel you have.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Machine mass | kg | Mass of the machine. |
| Number of wedges | Number of levelling wedges under it. | |
| Share of the weight on the worst wedge | % | Share of the total weight on the most heavily loaded wedge (uneven mass distribution). |
| Wedge angle | ° | Angle of the wedge slope. |
| Coefficient of friction (both faces) | Friction coefficient on both sliding faces. | |
| Height adjustment needed | mm | Total height adjustment needed at the wedge. |
| Wedge travel available | mm | Travel the wedge design allows. |
| Drive force available (screw or tool) | N | Force the adjusting screw or tool can apply to the wedge. |
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: Machine mass
- What it is
- The total mass of the machine resting on the levelling wedges, including fixtures, tooling and any fluids it holds.
- Units and format
- Enter a number in kg: kilograms. The form accepts 0.000001 kg to 10000000 kg. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 4000 kg as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Wedge load, drive force and withdraw force are proportional to it.
What this means: Number of wedges
- What it is
- The number of levelling wedges the machine stands on.
- Units and format
- Enter a plain number with no unit. The form accepts 1 to 100. Use a whole number. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 4 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- With the worst-wedge share, the shares must add up to at least the whole weight.
What this means: Share of the weight on the worst wedge
- What it is
- Units and format
- Enter a number in %: percent: the number is read as a percentage, so type 8 for 8 %. The form accepts 1% to 100%. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 35% as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The load on the worst wedge and its drive force are proportional to it.
- Get it right
- Do not simply divide equally unless the centre of mass is central; the heavy end carries more.
What this means: Wedge angle
- What it is
- The angle of the sloping face of the wedge to its base, from the levelling element’s data.
- 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
- Travel needed falls as the angle grows; lift per millimetre of travel rises.
- Get it right
- A smaller angle gives finer lift and self-locks more easily but needs more travel.
What this means: Coefficient of friction (both faces)
- What it is
- The friction coefficient on the sliding faces of the wedge, taken as the same on both faces, from test or maker’s data for the surfaces and lubrication.
- 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.
- Get it right
- Lubricated faces have much lower friction and may not self-lock.
What this means: Height adjustment needed
- What it is
- The total height change needed at the wedge to bring the machine level.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0 mm to 500 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 5 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Wedge travel needed is proportional to it.
What this means: Wedge travel available
- What it is
- The horizontal travel the wedge design allows, from the levelling element’s data.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 2000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 60 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Drive force available (screw or tool)
- What it is
- The horizontal force the adjusting screw or tool can push the wedge with, from the screw design or the maker’s data.
- Units and format
- Enter a number in N: newtons. The form accepts 0.000001 N to 100000000 N. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 8000 N as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Use the force on the wedge, not the torque on the screw.
Method and formulas
- Load on the worst wedge W = mass × g × share.
- Drive force = W tan(α + 2φ); withdraw force = W tan(2φ − α); self-locking if 2φ > α, with φ = tan⁻¹ μ (as the wedge force tool).
- Travel = height ÷ tan α; lift per millimetre of travel = tan α.
- Example: the worst wedge carries 13.729 kN, needs 5,845.2 N to drive and 47.572 mm of travel for 5 mm.
Limitations
- Guided wedge with equal friction on both faces; the adjusting screw’s own friction is extra.
- Static levelling; vibration can loosen wedges that are only just self-locking.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Choose levelling wedges for a machine installation
- Check that wedges can be adjusted under load
- Size a wedge for a fixture or press bed
Who it is for
- Millwrights
- Machine installers
- Maintenance engineers
What you get
- Load on the worst wedge
- Drive and withdraw forces and self-locking
- Travel needed and lift per millimetre
Interpreting the result
- A smaller wedge angle needs less force and gives finer adjustment, but 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.
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
Levelling and soft foot
In Shaft Alignment by the Numbers
What it covers: How levelling wedges set a base and whether they hold, what soft foot is, how to measure it at every foot, how to tell parallel, angled and induced soft foot apart, and how to shim.
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Open the Machine Levelling Wedge Check (Drive Force, Self-Locking, Travel) calculator