When choosing an electric pallet stacker, buyers often focus on the rated capacity, such as 1,000 kg, 1,500 kg, or 2,000 kg. However, the rated capacity does not mean the stacker can safely lift that weight at every load position.
The load center is another important specification. If the load center becomes larger, the load moves farther away from the stacker's fork face, increasing the overturning moment and potentially reducing the usable lifting capacity.
For this reason, buyers should consider load weight, pallet dimensions, load center, lift height, and mast configuration together when selecting an electric pallet stacker.
What Is the Load Center of an Electric Pallet Stacker?
The load center is the horizontal distance from the fork face to the approximate center of gravity of the load.
For a symmetrical palletized load, the load center is often approximately half of the load depth.
For example:
| Load Depth | Approximate Load Center |
|---|---|
| 800 mm | 400 mm |
| 1,000 mm | 500 mm |
| 1,200 mm | 600 mm |
| 1,400 mm | 700 mm |
If a pallet is 1,000 mm deep and the load is evenly distributed, its theoretical load center is approximately 500 mm.
This is why many electric pallet stackers and forklifts specify a 500 mm load center in their rated capacity data.
The important point is that the rated capacity is tied to a specific load-center condition rather than being a universal maximum weight. OSHA also notes that lifting capacity decreases as the load is raised, so load center and lift height need to be considered together.
Why Does Load Center Affect Rated Capacity?
The basic reason is leverage.
Imagine an electric pallet stacker carrying a 1,500 kg load with a 500 mm load center.
The approximate load moment can be represented as:
Load Moment = Load Weight × Load Center
Therefore:
1,500 kg × 0.5 m = 750 kg·m
Now suppose the same 1,500 kg load has a 600 mm load center:
1,500 kg × 0.6 m = 900 kg·m
The load weight has not changed, but the forward load moment has increased by:
900 ÷ 750 = 1.20
That represents a 20% increase in load moment.
This is why a pallet that weighs less than the stacker's nominal capacity can still require additional consideration if its center of gravity is farther forward.
Example: 1,500 kg Electric Pallet Stacker
Consider a hypothetical electric pallet stacker rated at:
Rated capacity: 1,500 kg
Rated load center: 500 mm
Lift height: 3,000 mm
A buyer wants to handle a pallet weighing 1,400 kg.
Case 1: 500 mm load center
The load moment is:
1,400 × 0.5 = 700 kg·m
The load is within the nominal 1,500 kg rating, subject to the manufacturer's rated configuration and load chart.
Case 2: 700 mm load center
The load moment becomes:
1,400 × 0.7 = 980 kg·m
That is approximately 40% higher than the 500 mm load-center case.
Therefore, simply looking at the 1,500 kg capacity is not enough. The buyer should provide the actual pallet dimensions and load distribution to the stacker supplier.
The exact permissible capacity must come from the manufacturer's rating for the specific machine configuration.
Does a Longer Pallet Always Reduce Capacity?
Not automatically, but a longer load can move the center of gravity farther away from the fork face.
For example, a pallet measuring 1,200 mm in depth may have an approximate 600 mm load center when the load is evenly distributed.
However, the actual center of gravity can be different.
Consider a 1,200 mm-deep pallet:
Load evenly distributed: approximately 600 mm center
Heavy products concentrated toward the rear: center may be less
Heavy products concentrated toward the fork tips: center may be greater
This is particularly important for irregular loads, long products, machinery components, steel products, or loads extending beyond the pallet.
Load Center and Lift Height Work Together
Load center is only one part of the capacity calculation.
Lift height also matters.
A stacker may have a nominal capacity of 1,500 kg, but its capacity at a particular high lifting position may be lower depending on the machine design.
For example, a manufacturer could specify different capacities for:
1,500 kg at lower lift height
1,400 kg at medium lift height
1,200 kg at maximum lift height
These numbers are only an illustration; the actual capacity must always be taken from the specific stacker's load chart or data plate.
Real forklift load charts demonstrate this principle: capacity can change with both load center and lift height.
How Should Buyers Check Load Center Before Ordering?
Before requesting a quotation for an electric pallet stacker, prepare these five parameters:
1. Maximum load weight
Use the heaviest normal working load rather than the average load.
For example:
Maximum palletized load = 1,350 kg
2. Pallet depth
Measure the pallet from the fork entry side to the back.
Example:
Pallet depth = 1,200 mm
3. Actual load distribution
Determine whether the load is evenly distributed.
An uneven load can have a different center of gravity from the geometric center of the pallet.
4. Required lift height
State the actual required fork height.
For example:
Required lift height = 4,500 mm
5. Working environment
Also tell the supplier whether the stacker will be used in:
Warehouse aisles
Production facilities
Loading areas
Retail storage
Logistics centers
Cold or humid environments
The supplier can then select an appropriate capacity, mast, battery and chassis configuration.
What Does a 500 mm Load Center Mean for Buyers?
A 500 mm load center is useful as a standard reference because it corresponds approximately to the center of a 1,000 mm-deep evenly distributed load.
But it should not be interpreted as a universal rule.
If your load is:
Longer than the standard pallet
Offset from the fork face
Unevenly distributed
Suspended
High-density
Extending beyond the pallet
you should provide the actual load dimensions and center of gravity to the supplier.
A capacity rating should always be evaluated together with the manufacturer's load chart and data plate.
Practical Example: Choosing a Stacker for a Warehouse
Suppose a warehouse handles:
Maximum load: 1,200 kg
Pallet size: 1,000 × 1,200 mm
Load center: approximately 600 mm
Required lift height: 4,000 mm
Indoor operation
Multiple lifting cycles per hour
Instead of simply searching for a "1.2 ton electric pallet stacker," the buyer should provide all of these parameters to the supplier.
The supplier can then determine whether a 1,200 kg-rated model is appropriate or whether a higher-capacity configuration is required for the specified 600 mm load center and 4,000 mm lift height.
Load Center Checklist for Electric Pallet Stacker Buyers
Before purchasing, check:
Maximum load weight
Pallet depth
Actual load center
Load distribution
Required lift height
Mast type
Fork dimensions
Rated capacity at the required configuration
Battery capacity
Aisle width
Floor conditions
Final Takeaway
The rated capacity of an electric pallet stacker cannot be evaluated by weight alone.
Load center determines how far the load acts forward from the stacker, while lift height and mast configuration can also affect usable capacity.
For example, a 1,500 kg stacker rated at a 500 mm load center should not automatically be assumed to safely handle 1,500 kg when the actual load center is 700 mm.
For an accurate equipment recommendation, provide the supplier with the maximum load weight, pallet dimensions, load center, and required lift height. This allows the stacker to be matched to the real working conditions rather than just its nominal capacity.