Mast specification trips up more forklift buyers than any other decision, because three different heights matter and most people only think about one of them.
Get Free Quotes 👑Every mast has three numbers that matter. Maximum fork height is how high the forks go, and it is the number everyone asks about. Overall lowered height is how tall the truck is with the mast down, which determines whether it fits through a door or into a trailer. Extended height is how tall the mast reaches when fully raised, which determines whether it clears sprinklers, ductwork and ceiling. Specifying only the first number is how trucks arrive that cannot get into the building.
Free lift is how far the forks rise before the mast itself begins to extend upward. It matters any time you are working in a height-restricted space, because within the free lift range you can raise a load without the truck getting taller. Loading inside a trailer or a shipping container is the classic case: without adequate free lift, the mast starts growing the moment you lift and hits the roof. Full free lift masts are specified exactly for this work.
A two-stage or duplex mast has one moving section inside the outer rails. It is the simplest and cheapest configuration, offers good visibility through the mast, and suits general work where lift height is moderate and overhead clearance is not tight. Standard two-stage masts have limited free lift, since the inner section starts rising almost immediately.
A three-stage or triplex mast adds another telescoping section, which delivers substantially greater lift height from a lower collapsed height. That combination is why three-stage is the common choice for warehouses with racking: you get the reach for the top beam level while still fitting under doors. Three-stage masts are usually available with full free lift, making them the practical default for mixed racking and container work.
A four-stage or quad mast packs maximum lift height into the lowest possible collapsed height and is used where racking is very tall or where the truck must pass through a low opening to reach a high storage area. The trade-offs are cost, more mast structure obstructing the operator view, additional maintenance points, and generally lower capacity at full height.
A forklift cannot carry its full rated load to the top of a tall mast. Raising the load lifts the combined center of gravity, which reduces lateral stability, so the manufacturer publishes a capacity that steps down at greater heights. On a tall three or four-stage mast, capacity at maximum height can be well below the figure on the plate. If you are storing heavy pallets at the top beam, check the capacity at that height rather than the headline number.
Work from measurements rather than assumptions. Measure the lowest doorway the truck must pass through, including any roll-up door track and overhead obstruction. Measure to the sprinkler heads and the lowest ceiling obstruction, not the ceiling itself. Measure the height of your top beam level plus the height of the pallet being placed. The mast has to satisfy all three constraints at once, and that is the specification you give the dealer.
Loading inside a trailer or container sets the hardest constraints on a mast. Both the overall lowered height and the free lift matter, and the truck has to work in a space where the mast cannot extend. This is also where tire type and overall width come in. If container or trailer loading is part of the job, say so when specifying, because it drives the mast choice more than warehouse racking does.
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How far the forks rise before the mast itself begins to extend upward. It matters in height-restricted spaces like trailers and containers, where without adequate free lift the mast grows the moment you lift and hits the roof.
A three-stage mast adds a telescoping section, delivering greater lift height from a lower collapsed height. That is why it is common in warehouses with racking, and it is usually available with full free lift.
Yes. Raising the load lifts the combined center of gravity and reduces lateral stability, so manufacturers publish capacity that steps down with height. On a tall mast, capacity at maximum height can be well below the plate figure.
The lowest doorway the truck must pass through including door track, the height to sprinkler heads and the lowest overhead obstruction, and your top beam level plus pallet height. The mast must satisfy all three at once.
One with a low overall lowered height and adequate free lift, since the mast cannot extend inside the container. Mention container or trailer work when specifying, because it drives mast choice more than racking does.
When racking is very tall or the truck must pass through a low opening to reach high storage. The trade-offs are cost, more mast structure blocking the view, extra maintenance points, and generally lower capacity at full height.