Live Bottom Trailer: How Conveyor-Floor Trailers Haul and Unload Asphalt

A live bottom trailer is a semi-trailer with a conveyor belt (or chain-and-slat system) for a floor. Instead of raising the bed to dump, the driver runs the conveyor, which carries material out through a gate at the rear. Because the body never tips up, live bottoms can unload under overhead wires, on uneven ground, and while moving, which makes them popular for hauling asphalt, aggregate, and soil. They also feed paver hoppers smoothly. The trade-offs are higher purchase cost, extra weight, and more moving parts to maintain.

Tons of asphalt in a dump truck →

How It Works

1. Material is loaded from the top at the plant or pit.
2. At the job, the driver opens the rear gate and engages the conveyor, often hydraulically powered from the tractor.
3. The belt carries material out at a controllable rate, into a paver hopper, a windrow, or a pile.
4. The trailer can creep forward while unloading to spread material.

Flowboy is a brand name so tied to the design that many people use it generically, and several other manufacturers build them.

Live Bottom vs End Dump vs Belly Dump

Trailer	How it unloads	Strengths	Weaknesses
Live bottom	Conveyor out the rear	No tipping, works under wires, metered unloading	Costs more, heavier, belt maintenance
End dump	Bed raises and tips out the rear	Simple, handles large rock and debris	Tip-over risk on soft or uneven ground, overhead hazards
Belly (bottom) dump	Gates open underneath to lay a windrow	Fast spreading of aggregate on roads	Can't make piles easily, needs windrow pickup for paving

Why Paving Contractors Like Them

• Safety: no raised bed means less risk of tip-overs and contact with power lines.
• Smooth paver feeding: the conveyor delivers mix at a steady rate, and the trailer doesn't need to bump the paver as hard.
• Less spilled mix: controlled discharge reduces spills around the paver.
• Night work and tight sites: useful under bridges, in parking garages and on sites with overhead obstructions.

Some crews also find that metering material out of a live bottom helps reduce the coarse-rock pileups that can happen when a big load slides out of a tipped bed all at once, though loading practices at the plant matter too.

Drawbacks

• Conveyor belts and floors wear, especially with sharp rock or demolition debris.
• Extra weight of the conveyor system can reduce legal payload compared with a lighter end dump, depending on the build.
• Hot asphalt can stick to belts without a suitable release agent.
• Higher purchase price and more hydraulic components to service.
• Large boulders or frozen chunks can jam or damage the system.

Hauling Hot Mix

Asphalt must stay hot from plant to paver. Many live bottom trailers can be fitted with insulated sides and tarps. Crews spray the belt with an approved release agent before loading so mix doesn't stick. Diesel fuel shouldn't be used as a release agent, since it damages asphalt and is prohibited by many agencies. Our article on asphalt release agents covers safer options. A mesh or vinyl dump truck tarp helps hold heat and is legally required for loose loads in many areas.

How Much a Trailer Holds

Capacity depends on the trailer's length, sides and the tractor combination, plus local weight limits. Semi-trailers typically haul more than a single-axle or tandem dump truck. For how loads compare in tons, see our guide to tons of asphalt in a dump truck.

Other Uses

• Aggregate and sand delivery
• Topsoil and mulch
• Agricultural products like grain, silage and fertilizer
• Road salt and sand
• Recycled asphalt and millings

Belt vs Chain Floors

Most asphalt haulers use a rubber belt that runs the length of the trailer, which gives a smooth, sealed floor that holds fine material and hot mix well. Some trailers use a chain-and-slat or walking-floor style instead, which can handle rougher materials like demolition debris or large rock but may leak fines. Belt condition is the main wear item; a torn or glazed belt affects unloading and must be replaced, which is a significant expense. Ask how belts are rated for heat if you'll haul asphalt regularly.

Buying Tips

• Inspect the belt or chain condition, rollers and bearings.
• Check hydraulic motors, hoses and the rear gate.
• Look at the frame for cracks, especially around suspension.
• Ask about the belt material's heat rating if you'll haul asphalt.
• Confirm the tractor's wet kit supports the conveyor's hydraulic needs.

Maintenance

Keep belts clean and tracked straight, grease bearings, and check hydraulic systems. Clean out asphalt and aggregate at the end of the day. A cordless grease gun makes routine lubrication faster, and long-handled scrapers help remove stuck material.

Live Bottoms at the Paver

When feeding a paver, the driver backs up until the trailer's rear is over the paver hopper, then engages the conveyor while the paver pushes or follows. Coordination between the driver and paver operator keeps the hopper full without spilling. Because the conveyor speed can be adjusted, drivers can slow discharge when the hopper is nearly full instead of dumping everything at once. On jobs with a material transfer vehicle, live bottoms unload into its hopper instead, and the transfer vehicle feeds the paver.

Bottom Line on Live Bottom Trailers

A live bottom trailer unloads with a conveyor floor instead of tipping, making it safer around overhead hazards and smoother for feeding pavers. It costs more and needs belt maintenance, but it's a strong choice for hauling hot mix, aggregate and bulk materials.