The mast type determines how high the truck can lift and what free height it requires. Duplex mast lifts up to approx. 4 m triplex mast up to approx. 7.5 m and special masts over 16 m. The lift height affects capacity — the higher the less you can lift.
Introduction
The mast type is one of the first things to check when assessing whether the truck can do a job: can it lift to the necessary height and what is the free height on the site? And remember that lift height reduces capacity — see the load diagram.
The three basic types
| Mast type | Typical max. lifting height | Note |
|---|---|---|
| Duplex mast (2-tier). | op til ca. 4 m | Simple and robust; small ground clearance requirement |
| Triplex mast (3-stage) | op til ca. 7,5 m | Standard on high-rack storage |
| Specialty mast | over 16 m | Narrow-aisle trucks and special high-bay systems |
Clearance height in the hall
The clearance height in the warehouse, in gates and under pipes and sprinkler systems sets the limit for what mast type you can use. The clearance height must be measured and documented as part of truck selection. For narrow aisle trucks, the purchase checklist also specifies a minimum cabin height of 160 cm.
Lifting height and capacity
The higher you lift, the more the allowed load drops. This is clearly shown on the load chart: in the Toyota example (nominal 1,600 kg at 500 mm load center) the capacity drops from 1,600 kg at 3,000 mm lifting height to 750 kg at 7,000 mm – with the same load center. Mast type and lifting height are two of the most important parameters to read on the load chart.
- 01Always check the clearance in the hall, under gates and at sprinkler systems before you choose mast type.
- 02Duplex mast: low construction height — good for halls with low ceiling height.
- 03Triplex mast: lifts high with small free height in lowered state ("freestanding mast" variant)
- 04Specialty masts over 16 m typically require narrow-aisle trucks and special warehouse design.
Free lift and full free lift
Two concepts are crucial when headroom is low, or you work in a container or lorry: free-lift and full free-lift. They deal with how high the forks can be raised BEFORE the mast itself starts to grow in height.
- 01Free lift: the height the forks can be raised before the inner/outer mast begins to telescope upward. If the free lift is small, the mast 'shoots up' as soon as you lift — a problem under a low ceiling or in a container.
- 02Full free-lift: the forks can reach almost their full height within the mast's own lowered height, typically via an extra centre cylinder. This makes it possible to stack in two layers inside a standard container where total height is limited.
The terminology for masts and truck types is defined in ISO 5053-1. The precise free lift height for a specific truck is in the manufacturer's data sheet — find it there, not by guessing.
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