The mast configuration is one of the most important factors when selecting an electric stacker. It directly affects the available lifting height, overall mast height, operating space, and suitability for different warehouse applications.
The two common configurations are duplex mast and triplex mast. Although both can provide efficient electric lifting, their mechanical structures and operating characteristics are different.
For buyers comparing electric stackers, understanding these differences can help determine whether a duplex or triplex configuration is more suitable for a specific warehouse or storage application.
What Is a Duplex Electric Stacker?
A duplex electric stacker uses a two-stage telescopic mast. The mast consists of an outer section and a movable inner section that extends upward during lifting.
A typical duplex electric stacker may have lifting heights such as:
| Specification | Example |
|---|---|
| Load Capacity | 1,500 kg |
| Load Center | 500 mm |
| Mast Type | Duplex |
| Lift Height | 2,500–3,500 mm |
| Maximum Lift Height | 3,500 mm |
| Overall Height | Approx. 2,250 mm |
| Fork Length | 1,070 mm |
For example, a 1.5-ton duplex electric stacker with a 3,000 mm lifting height can be suitable for warehouses where pallet storage is normally arranged on the first two or three rack levels.
The relatively simple mast structure also makes duplex models a practical option when extremely high lifting is not required.
What Is a Triplex Electric Stacker?
A triplex electric stacker uses a three-stage telescopic mast. It allows the forks to reach a greater height while keeping the collapsed mast relatively compact.
For example:
| Specification | Example |
|---|---|
| Load Capacity | 1,500 kg |
| Load Center | 500 mm |
| Mast Type | Triplex |
| Lift Height | 3,500–5,000 mm |
| Maximum Lift Height | 5,000 mm |
| Overall Height | Approx. 2,250 mm |
| Fork Length | 1,070 mm |
A triplex electric stacker with a 5,000 mm lift height can therefore be used for higher pallet racks while maintaining a relatively low mast height when the forks are lowered.
This feature is particularly useful when a warehouse has high storage racks but limited clearance at doors, ceilings, or other low-height areas.
Duplex vs. Triplex Electric Stacker
The main difference between the two configurations is the relationship between maximum lifting height and collapsed mast height.
| Feature | Duplex Mast | Triplex Mast |
|---|---|---|
| Mast Sections | 2 | 3 |
| Typical Lift Height | 2.5–3.5 m | 3.5–5.0 m |
| High-Level Storage | Moderate | Excellent |
| Collapsed Height | Depends on design | Can remain relatively low |
| Structure | Simpler | More complex |
| Suitable Applications | Standard warehouse racks | High-bay storage |
| Cost | Generally lower | Generally higher |
| Lifting Requirement | Medium | High |
The actual specifications vary by electric stacker model, so buyers should always check the manufacturer's technical data rather than selecting a mast configuration based only on the name.
Numerical Example: 3.0 m vs. 5.0 m Lift Height
Consider a warehouse using pallets that are approximately 1.2 m high, with three storage levels.
Suppose the required fork lifting heights are:
Ground level: 1.0 m
Second level: 2.5 m
Third level: 3.0 m
A 3.0 m duplex electric stacker may provide sufficient lifting height for this application.
Now consider another warehouse with pallet rack levels at approximately:
First level: 1.5 m
Second level: 3.0 m
Third level: 4.2 m
Fourth level: 5.0 m
A 3.0 m duplex stacker would not provide enough lifting height for the upper rack positions. A 5.0 m triplex electric stacker would be more appropriate from a lifting-height perspective.
This example shows why buyers should determine the required fork height before choosing the mast type.
Why Collapsed Mast Height Matters
Maximum lift height is not the only parameter that should be considered.
Imagine two electric stackers:
Model A
Lift height: 3,500 mm
Overall mast height: 2,350 mm
Model B
Lift height: 5,000 mm
Overall mast height: 2,300 mm
Although Model B can lift approximately 1,500 mm higher, its lowered mast height can be similar to Model A because of its three-stage mast construction.
This can be important when the stacker needs to pass through:
Warehouse doors
Container entrances
Low ceilings
Mezzanine areas
Narrow storage aisles
Therefore, buyers should evaluate both maximum lift height and lowered mast height.
How Does Mast Configuration Affect Warehouse Operations?
Mast configuration affects where and how an electric stacker can be used.
Standard Warehouse Storage
For warehouses with rack heights around 2.5–3.5 m, a duplex electric stacker may provide sufficient lifting capability.
Typical applications include:
General warehousing
Retail storage
Small distribution centers
Manufacturing workshops
Spare-parts warehouses
High-Bay Storage
For rack heights of approximately 4–5 m or higher, a triplex configuration can provide additional lifting capability.
Typical applications include:
High-bay warehouses
Logistics centers
Distribution facilities
Large manufacturing warehouses
High-density pallet storage
However, lift height alone does not determine whether a stacker can safely operate at a particular rack position. The rated load capacity at the required lifting height must also be checked.
Does Lift Capacity Change at Higher Heights?
Yes. Buyers should pay attention to the load capacity at different lift heights.
For example, an electric stacker may be rated at:
1,500 kg at a 500 mm load center
but its permitted load may be lower at maximum lift height depending on the mast design and load chart.
A simplified example could look like this:
| Lift Height | Example Rated Capacity |
|---|---|
| 2,000 mm | 1,500 kg |
| 3,000 mm | 1,500 kg |
| 4,000 mm | 1,300 kg |
| 5,000 mm | 1,100 kg |
These numbers are illustrative only. Actual capacity must come from the manufacturer's load chart for the specific electric stacker.
For example, if a warehouse needs to place a 1,300 kg pallet at 5,000 mm, a stacker rated at 1,500 kg nominal capacity may not necessarily be suitable. The buyer needs to confirm the actual capacity at 5,000 mm lift height and the specified load center.
How to Choose Between Duplex and Triplex
A practical selection process can start with four questions.
1. What is the required lifting height?
Measure the actual rack storage height and determine the required fork height.
For example:
Required lift height: 2,800 mm → duplex may be sufficient
Required lift height: 4,000 mm → triplex may be preferable
Required lift height: 5,000 mm → triplex configuration is commonly considered
2. What is the maximum available clearance?
Measure the lowest warehouse door, ceiling, container entrance, and other obstacles.
A stacker must be able to move through these areas with the mast fully lowered.
3. What is the actual pallet weight?
Do not select the stacker only according to its nominal capacity.
For example, if the pallet weighs 1,200 kg, check whether the machine can safely handle 1,200 kg at the required lifting height and load center.
4. How frequently will high-level stacking be performed?
If the machine only occasionally lifts pallets to around 3 m, a duplex configuration may meet the application.
If operators frequently place pallets at 4–5 m, a triplex configuration can provide greater lifting capability.
Duplex or Triplex: A Simple Buying Example
Suppose two customers are purchasing a 1.5-ton electric stacker.
Customer A:
Maximum rack height: 3,000 mm
Door height: 2,500 mm
Pallet weight: 1,000 kg
Normal warehouse operation
A duplex electric stacker with approximately 3,000–3,500 mm lift height could be considered, subject to its load chart and clearance requirements.
Customer B:
Maximum rack height: 5,000 mm
Door height: 2,400 mm
Pallet weight: 1,200 kg
Frequent high-level pallet storage
A triplex electric stacker with approximately 5,000 mm lift height may be considered, provided its rated capacity at 5,000 mm meets the 1,200 kg requirement.
The two customers may both need a 1.5-ton electric stacker, but their mast requirements are different because their warehouse conditions are different.
Final Considerations for Electric Stacker Buyers
Choosing between a duplex and triplex mast should not be based solely on the maximum lifting height.
Before purchasing an electric stacker, buyers should confirm:
Required lifting height
Lowered mast height
Door and ceiling clearance
Rated load capacity at the required height
Load center, commonly 500 mm
Pallet dimensions
Aisle width
Battery capacity and operating hours
Fork dimensions
Warehouse floor conditions
In general, duplex electric stackers are commonly suitable for medium-height storage, while triplex electric stackers are designed to provide greater lifting heights while maintaining a relatively compact lowered mast.
The final choice should be based on the actual rack height, clearance restrictions, pallet weight, and required operating conditions of the warehouse.