Flatbed, dropside, fence, tipper, dry van, container chassis, steel coil and municipal — what each category is for, and how to tell which one your load needs.
A flat deck is a platform with nothing above it. Load from any side, from above with a crane, or from the rear — nothing is in the way.
That openness is the whole argument and the whole limitation. Nothing protects the cargo, so everything depends on how it is secured, and the trailer's useful rating is its concentrated load figure rather than its payload: a flat deck fails where the load concentrates, not where it totals.
A step deck lowers the rear section to buy height clearance for tall machinery. It costs loading simplicity and gains headroom — worth it only if your tallest regular item will not otherwise clear.
Buy a flat deck if: your loads vary, you load with a crane or from the side, or you carry machinery and project cargo.
Add sides to a flat deck and you get containment without losing overhead access. Two categories, and the difference between them is height.
A dropside trailer has solid sides to deck-board height that come off or fold down. It is bought for loading access: how fast the side comes away is the whole specification, which is why the panel arrangement — removable, fold-down, welded, split-opening — matters more than anything else about the vehicle.
A fence trailer has a taller body with an upper lattice. It is bought for volume: cargo that fills the space before it reaches the axle limit. The lattice contains a light bulky load without adding a roof, so it still loads from above.
The rule of thumb: dropside for access, fence for cubic metres.
A tipping body unloads itself, which for bulk material is worth more than everything else combined.
Side tipping discharges across the width. Fast, suits free-running material, and needs ground level enough to tip across the axis of the vehicle safely.
Rear tipping discharges over the tail from a shorter and taller body at a steeper angle. It clears material that sticks — wet sand, clay-bound aggregate — and tips on ground where a side tip would be uncomfortable.
What decides it is your material and your ground, in that order. What both share: on a haul road it is the frame that fails, not the body.
A sealed box on wheels. Weather out, cargo in, nothing reachable at a border queue or an overnight stop.
A dry van is bought by the cubic metre rather than by the tonne — you run out of space long before you run out of axle — so the numbers that matter are the internal ones, and specifically internal height, because that is where a stack either uses the box or wastes it.
The category has four names in English (box, enclosed, cargo, dry van) and three of them mean something much smaller in North America. Worth knowing before you send an enquiry.
A container chassis — also sold as a skeleton trailer — is a frame with lock positions and no deck. It carries boxes and nothing else, and it does that better than a platform because it is lighter and purpose-built.
The specification is lock count first, frame type second. Lock count decides which box plans the frame covers; gooseneck or straight frame decides loaded height, which decides whether you clear your route.
Buy a chassis rather than a platform if containers are most of your traffic. Buy the platform if they are occasional and you carry other things in between.
Coil is the load that breaks the general rules, which is why it has a trailer of its own.
It is extremely dense, it is round, and it concentrates its whole mass into a very small footprint. A recessed well lets the coil sit down into the frame rather than on top of it, dropping the centre of gravity and taking the load path into the main beam instead of across the deck plate. Anti-sway clamps stop it rotating, which is the entire safety case for the vehicle.
The deck is deliberately short — 8 to 9.5 m rather than 12 to 13 — because with a load this dense the deck length that matters is the one that puts the weight over the axles.
Not every special purpose vehicle is a trailer. Two of ours are rigid vehicles, and they belong in any honest categorisation because buyers arrive looking for them alongside the trailers.
A water tanker truck — a water bowser in Commonwealth markets — carries and discharges water for dust control, site damping, street washing or delivery. It is specified backwards from the duty: what the water is for, where it comes from, and how far away that is.
A dust suppression truck treats airborne dust with a mist cannon rather than wetting the ground. Ours is built on a battery-electric chassis, which matters most on enclosed sites where a diesel unit is restricted or prohibited.
Four questions, in this order, and they usually eliminate seven of the categories above.
How does the load get on? From above with a crane rules out enclosed. From the side rules in dropside and fence. Driven or rolled on rules in flat decks with ramp access.
Does volume or weight fill you first? Volume points at fence and dry van. Weight points at tippers, flat decks and coil trailers.
How does it come off? If it tips, you want a tipping body — nothing else comes close on turnaround.
Does it need protecting? Weather, theft or contamination all point at the enclosed body regardless of the other three answers.
If two categories survive those four questions, the side-by-side comparison works through the trade-offs.
