BIZOMAT MAKEOS · Mechanics
Forklift Load Centre Check (Load Centre of Gravity, Derated Capacity, Side Offset)
For a load made of several items on the forks, where is its centre of gravity, what can the forklift lift at that load centre, and is the load within it?
Check of a forklift lift: the combined mass and centre of gravity of up to three items on the forks measured from the fork face (as the combined centre of gravity tool), the capacity at that load centre from the rated capacity and rated load centre by the balance of moments about the front axle, and the sideways offset of the load, against the load mass and an offset limit.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Rated capacity | kg | Rated capacity on the truck’s data plate. |
| Rated load centre | mm | Load centre at which the rated capacity applies. |
| Front axle to fork face | mm | Distance from the front axle (tipping line) to the fork face. |
| Item 1 | ||
| Mass (0 = unused) | kg | Mass of item 1. |
| Distance of its CG from the fork face | mm | Distance of item 1’s centre of gravity from the fork face. |
| Sideways offset of its CG from the truck centre line | mm | Sideways offset of item 1. |
| Item 2 | ||
| Mass (0 = unused) | kg | Mass of item 2. |
| Distance of its CG from the fork face | mm | Distance of item 2’s CG from the fork face. |
| Sideways offset of its CG from the truck centre line | mm | Sideways offset of item 2. |
| Item 3 | ||
| Mass (0 = unused) | kg | Mass of item 3. |
| Distance of its CG from the fork face | mm | Distance of item 3’s CG from the fork face. |
| Sideways offset of its CG from the truck centre line | mm | Sideways offset of item 3. |
| Largest sideways offset | mm | Largest sideways offset of the combined CG 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: Rated capacity
- What it is
- The rated lifting capacity shown on the truck’s capacity plate, which applies at the rated load centre.
- Units and format
- Enter a number in kg: kilograms. The form accepts 0.000001 kg to 1000000 kg. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2500 kg as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The capacity at the actual load centre scales in direct proportion.
- Get it right
- Use the plate value for the mast, lift height and any attachment fitted; the basic brochure capacity may not apply.
What this means: Rated load centre
- What it is
- The distance from the fork face to the load centre of gravity at which the rated capacity applies, as stated on the capacity plate.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 10000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 500 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Read it from the same plate as the rated capacity.
What this means: Front axle to fork face
- What it is
- The horizontal distance from the front axle centre, the tipping line, to the vertical face of the forks.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 10000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 450 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Take it from the truck maker’s data or measure it; attachments move the fork face forward.
Item 1
What this means: Mass (0 = unused)
- What it is
- The mass of the first item on the forks. Items with 0 are left out of the combined load.
- Units and format
- Enter a number in kg: kilograms. The form accepts 0 kg to 1000000 kg. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 800 kg as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Include pallets and packaging with the item, or enter them as another item.
What this means: Distance of its CG from the fork face
- What it is
- How far forward of the fork face the first item’s centre of gravity sits.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0 mm to 100000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 400 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Measure from the vertical fork face, not from the fork tips.
What this means: Sideways offset of its CG from the truck centre…
- What it is
- How far the first item’s centre of gravity sits to one side of the truck centre line.
- Units and format
- Enter a number in mm: millimetres. The form accepts -10000 mm to 10000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Use a sign for each side, positive one way and negative the other, so offsets on opposite sides cancel.
Item 2
What this means: Mass (0 = unused)
- What it is
- The mass of the second item on the forks. Items with 0 are left out of the combined load.
- Units and format
- Enter a number in kg: kilograms. The form accepts 0 kg to 1000000 kg. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 600 kg as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Include pallets and packaging with the item, or enter them as another item.
What this means: Distance of its CG from the fork face
- What it is
- How far forward of the fork face the second item’s centre of gravity sits.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0 mm to 100000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 900 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Measure from the vertical fork face, not from the fork tips.
What this means: Sideways offset of its CG from the truck centre…
- What it is
- How far the second item’s centre of gravity sits to one side of the truck centre line.
- Units and format
- Enter a number in mm: millimetres. The form accepts -10000 mm to 10000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 50 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Use a sign for each side, positive one way and negative the other, so offsets on opposite sides cancel.
Item 3
What this means: Mass (0 = unused)
- What it is
- The mass of the third item on the forks. Items with 0 are left out of the combined load.
- Units and format
- Enter a number in kg: kilograms. The form accepts 0 kg to 1000000 kg. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0 kg as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Include pallets and packaging with the item, or enter them as another item.
What this means: Distance of its CG from the fork face
- What it is
- How far forward of the fork face the third item’s centre of gravity sits.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0 mm to 100000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Measure from the vertical fork face, not from the fork tips.
What this means: Sideways offset of its CG from the truck centre…
- What it is
- How far the third item’s centre of gravity sits to one side of the truck centre line.
- Units and format
- Enter a number in mm: millimetres. The form accepts -10000 mm to 10000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Use a sign for each side, positive one way and negative the other, so offsets on opposite sides cancel.
What this means: Largest sideways offset
- What it is
- The largest sideways offset of the combined load centre of gravity from the truck centre line that you accept, either side.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0 mm to 10000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 100 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Take it from the truck maker or your site rules; the check compares the size of the offset, either side.
Method and formulas
- Combined mass and centre of gravity of the items (as the combined centre of gravity tool).
- Capacity at load centre c = Q (A + c₀) ÷ (A + c), from moments about the front axle.
- Utilisation = load ÷ capacity; sideways offset against the limit.
- Example: 1,400 kg with its CG 614.29 mm out; the truck can lift 2,231.5 kg there.
Limitations
- Moment balance only; the manufacturer’s capacity plate for the mast height and attachments governs.
- Load lifted low and level; tilting and lifting high reduce stability.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check a long or uneven load before lifting
- Find the capacity of a forklift at a longer load centre
- Arrange items on a pallet to keep within capacity
Who it is for
- Warehouse supervisors
- Riggers
- Safety advisers
What you get
- Load mass and centre of gravity
- Capacity at that load centre
- Load against capacity and offset
Interpreting the result
- Capacity falls as the load centre moves out: a load twice as deep as standard can roughly halve what the truck may lift.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 221–227, 153–163. Topic reference; no source tables or recommended settings are reproduced.
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