3 Axle 45 CBM Box-Type Rear Dump Semi Trailer

The 3 Axle 45 CBM Box-Type Rear Dump Semi Trailer is built for operators who move high volumes of light to medium density bulk and need cubic capacity more than raw tonnage. The body is a reinforced square box with vertical rib panels welded along each side wall, finished here in red, and it holds 45 cubic meters before you reach the 45 to 60 ton axle ceiling. A front-mount telescopic cylinder lifts the body to roughly 50 degrees, and an automatic gravity tailgate swings open as the load tips, so discharge stays clean without a second worker at the rear. HUAYU runs the box on a Q345B chassis with a three-axle mechanical leaf-spring group, the same haul-road running gear used across our tipper line. Sand, coal, grain, wood chips, and light aggregate are its daily cargo.

Why a Box Body Carries More Light Bulk Than a U-Shape

A U-shape rock body curves its floor into a half-round trough. That shape is the right call for dense, abrasive rock and ore, where the load sits low and the rounded floor sheds sticky material and spreads the impact of large stones. It gives up cubic volume to do that job. A square box body keeps vertical walls and a flat floor, so every cubic meter of the envelope is usable space. For cargo that fills the body by volume long before it hits the weight limit, the box returns more payload per trip.

Take grain or wood chips at roughly 0.4 to 0.6 tons per cubic meter. A 45 cubic meter box clears 18 to 27 tons of product and still has headroom, while a smaller-volume rock body would cube out first and run half empty on weight. The high side walls here are the whole point. They raise the fill line without forcing a second deck or a longer chassis.

The trade-off is honest. This trailer is not made to swallow blasted granite the way a rock body is. If your haul is dense rock, ore, or demolition rubble, the 3 axle U-shape rock body end dump is the correct tool and uses a thicker abrasion-grade floor. Match the body to the cargo density and you stop paying for capacity you cannot legally load.

Front-Mount Telescopic Cylinder and the Tipping Cycle

Front-mount hydraulic oil tank and valve bank

Telescopic tipping cylinder and hydraulic valve close-up

The cylinder sits at the front of the body, ahead of the cargo, and pushes the box up from its leading edge. A front-mount telescopic ram extends in stages, so one cylinder reaches the full tipping height of a long body without the side hinges a mid-mount design needs. The body lifts to about 50 degrees, steep enough that grain, sand, and damp coal slide out under their own weight.

The oil tank and the valve bank share the front cross-member, where the photos show the supply lines and the air-piloted control coupling. Running the hydraulics off the tractor power take-off keeps the trailer simple to service. There is one tank to check, one filter, and a single high-pressure line to inspect before each tipping cycle. HUAYU fits a brand-name telescopic cylinder as standard and can supply a HYVA cylinder on request when a fleet standardizes on one supplier. Keep the trailer on firm, level ground while tipping a full body, because a 45 cubic meter load raised to 50 degrees carries its center of gravity high and to the rear.

The Automatic Gravity Tailgate

Automatic gravity rear tailgate lock mechanism

Reinforced box dump body seen from the rear

Most box dumps make the driver climb down and unlatch the rear door by hand before every tip. This trailer uses an automatic gravity tailgate instead. The spring-loaded latch on the upper rail releases as the body starts to rise, the door swings out on its top hinges, and it falls shut again when the body lowers. One person tips the load from the cab without walking to the back of a raised trailer, which is where most tipping injuries happen.

The rear frame is boxed and gusseted at the corners, visible in the straight-on photo, so the door seals against a flat face and fine cargo does not leak from the bottom corners on the road. The latch is a wear item by design and bolts on, so it can be replaced without cutting into the body. For operators hauling dusty product through populated areas, a door that seals when shut and clears fully when open is the difference between a clean drop and a trail of spillage. The tailgate is standard on every unit, not an upcharge.

Running Gear Built for Loaded Haul-Road Cycles

Mechanical multi-leaf spring suspension pack

Three-axle group with CHENGSHAN tyres and steel rims

A dump trailer earns its keep on rough loading yards and unpaved approaches, so the running gear is plain mechanical rather than air. Three 13-ton axles ride on multi-leaf spring packs that absorb the shock of a body slamming down empty after a tip, and they cost less to repair in the field than an airbag system. The trailer rolls on CHENGSHAN 12R22.5 tires across twelve positions, including the spares.

Mechanical springs suit operators who value a part they can service anywhere over the ride comfort of air. Fleets that run long paved trunk routes between sites can order air suspension instead, which protects the chassis from harmonic road inputs over distance. If you are weighing the two, our note on air suspension airbag faults covers what changes in the maintenance schedule. FUWA or BPW axles are available when a fleet standardizes its hub and bearing stock. The main beam is Q345B in a double T-section, sized so the frame carrying capacity holds up under repeated full-load tipping.

The Rest of the Spec Stack

Two-speed landing gear support leg

• King pin: 2 inch or 3.5 inch, bolt-on for a quick swap between tractor fifth wheels
• Landing gear: 28-ton two-speed, shown in the photo with the low-gear crank for loaded parking
• Brakes: dual-line air braking with ABS, 24-volt electrical
• Lighting: 24-volt LED clusters, reflective side conspicuity tape, 7-pin socket
• Floor and walls: 6 mm floor plate, 4 mm side walls, Q345B throughout
• Finish: sandblast, two-part epoxy primer, then polyurethane topcoat in the color you specify

Who Actually Buys This Configuration

• Grain and feed haulers moving seasonal harvest by volume, where a high-side box fills the trip before it hits the axle limit
• Coal and coke transporters on regional routes who need cubic capacity for lower-density loads
• Sand and light aggregate suppliers running paved and graded haul roads between pit and batching plant
• Recycling and biomass operators carrying wood chips, husks, or compost that cube out long before they weigh out
• Mixed-cargo fleets that want one trailer for several light bulk products rather than a dedicated rock body

If your loads are dense rock or ore, size up to a 4 axle end dump or a U-shape rock body instead. Not sure which body fits your cargo? Our guide on how to choose a semi trailer walks through the trade-offs.

Frequently Asked Questions

How is this box body different from a U-shape rock body?

The box body has vertical walls and a flat floor, so it uses the full envelope for volume. A U-shape rock body curves the floor into a trough that handles dense, abrasive rock but holds less per cubic meter. Choose the box for light, high-volume cargo like grain, coal, and wood chips, and the U-shape for stone, ore, and demolition waste. The two are built for opposite ends of cargo density.

What cargo suits the 45 cbm high-side body?

Anything that fills the body by volume before it reaches the 45 to 60 ton axle limit. Grain, wood chips, husks, compost, coal, coke, sand, and light crushed aggregate are typical. At roughly 0.4 to 0.6 tons per cubic meter, 45 cubic meters of grain runs about 18 to 27 tons, which sits inside the legal payload with room to spare. Dense materials above 1.6 tons per cubic meter weigh out before they fill the box, so a smaller, heavier-duty body is the better match for those.

Can the volume and dimensions be customized?

Yes. The standard body is 45 cubic meters at 9.6 meters long, and we build 40 and 50 cubic meter versions on the same chassis by changing wall height and length. Side-wall height, floor and wall plate thickness, axle rating, and suspension type are all set per order. Send us the cargo density and your road legal limits, and we size the body to load full without running over weight.

What payload can three axles legally carry?

Three 13-ton axles give a nominal 39-ton axle group rating, and the trailer is rated 45 to 60 tons gross depending on axle and tire spec. The legal figure on the road depends on your country's per-axle and gross-combination limits, which vary widely across export markets. Tell us your destination and we set the axle rating and tire load index so the loaded trailer stays inside the local limit.

How does the automatic gravity tailgate work?

The rear door is hinged at the top and held by a spring latch on the upper rail. When the body rises to tip, the latch releases and the door swings outward under its own weight, then closes again as the body lowers. The driver never leaves the cab to unlatch it. The door seals against a boxed rear frame when shut, so fine cargo does not leak from the corners in transit.

What warranty comes with the trailer?

One-year warranty on the main beam, body structure, and welded joints. Component warranties follow the original manufacturer's terms (CHENGSHAN tires, and the axle, cylinder, and brake suppliers fitted on your build). The structural warranty covers the chassis and the welded box under normal loaded-tipping use.

Ask for a full quote with your destination port, the cargo you haul, and your preferred body volume (40, 45, or 50 cubic meters) and suspension type. The HUAYU sales team replies within one working day on weekdays. Reach us on the contact page or by WhatsApp from any page on the site.