Customers often ask for a specific trailer by name. In practice the load decides: its travel height, its weight, and whether it can be driven or must be lifted on.
Flatbed
A single level deck, open on all sides, loaded from the top, sides or rear. It suits building materials, steel, crated machinery, pipe and palletised freight that is within legal height once it is on the deck.
Because the deck sits high, a tall item on a flatbed can push the shipment over height limits even when the item itself would fit under a bridge on the ground.
Step deck
A step deck drops to a lower main deck behind the tractor, buying back height without changing anything about the load. It is the usual answer for machinery and equipment that is slightly too tall for a flatbed, and it can often be loaded by ramp.
Lowboy
A lowboy sits lowest of the three, with a well between the gooseneck and the rear axles, and it is built for tall, heavy machinery. Excavators, dozers and loaders travel here, and detachable goosenecks let a machine be driven straight on rather than craned.
Additional axles spread weight for heavier units, which also changes how the load is permitted and routed.
What actually decides it
Travel height with the boom, blade or mast in transport position; operating weight and where that weight sits; overall width including tracks; and the loading method available at the origin. Give us those four and the trailer question answers itself.
Have a load to move?
Send the dimensions, weight, and locations and dispatch will review what is required.