Asphalt Distributor Truck Product

Overview

An asphalt distributor truck sprays a thin, even layer of hot bitumen (asphalt binder) across a prepared road surface as a tack coat between layers or as a prime coat on a base. The machine consists of a large insulated Heated Tank Assembly heated by a Burner & Heating System, a Bitumen Pump & Drive circulating bitumen through a Spray Bar & Nozzles mounted on the rear, and controls allowing the operator to adjust Spray Nozzle flow and truck speed in unison.

A well-applied tack coat ensures adhesion between asphalt layers; under-spraying leaves poor bond, over-spraying wastes material and creates slippery roads. The operator must maintain even coverage and consistent application rate over the full width in a single pass.

How it works

The Engine & Transmission, a large turbodiesel, idles on the chassis and powers both the truck driveline and the Hydraulic Supply Pump via a power-take-off (PTO) coupling. The truck drives forward at a steady pace (typically 2–8 km/h during spraying) while the operator maintains control.

The Burner & Heating System, fired by diesel and controlled by the Temperature Thermostat, heats the bitumen in the tank to 140–180 °C. Modern tack coats are applied at lower temperatures (140–160 °C) to reduce oxidation; older "hot oil" applications ran hotter. The Thermal Insulation minimizes heat loss during storage and transport, and Tank Baffles inside the tank slow fluid movement, ensuring even temperature distribution.

The Gear Pump, a low-speed gear pump rated for heavy viscous fluids, draws hot bitumen from the tank bottom through a Intake Strainer intake strainer. The pump pushes the bitumen at 5–10 bar through the Spray Manifold manifold and out through the Spray Nozzle array. Typically 20–24 nozzles, arranged in two columns down the spray bar width, create a uniform fan pattern. Each nozzle can be adjusted for angle and orifice size to tune the spray profile.

The operator controls three main parameters: (1) truck speed, set by pushing the accelerator pedal; (2) spray rate, controlled by the Flow Rate Controller, a proportional valve that meters pump output; and (3) temperature, maintained automatically by the thermostat. The Ground Speed Sensor reads truck ground speed and, on newer machines, automatically adjusts spray rate to keep application rate constant (L/m²) as speed changes. On older machines, the operator manually adjusts spray rate to match speed.

The Height Adjustment Cylinder allows the operator to vary the height of the Spray Bar & Nozzles above the road — typically 0.3–0.6 m — to tune the spray pattern and avoid overspray. Hydraulic Proportional Solenoid Valve modules control both height and flow.

As the truck moves forward, the asphalt exits the nozzles in a fine mist, landing on the road as a thin film. The bitumen cools and begins to set within minutes, ready for the next layer — typically a layer of hot asphalt concrete mix is spread and compacted within 2–4 hours of tack coat application.

The tank can be filled from a stationary asphalt tanker truck while the distributor is warming up for the next job, or the distributor can drive to a terminal to be filled. The Drain Valve at the tank bottom allows complete emptying for cleaning between different grades or at end of season. Residual bitumen hardens in the pipes and nozzles if not cleaned immediately after use, so most jobs include a flush with kerosene or lightweight diesel to prevent clogging.

Typical applications include airport runway tack coats, highway overlay tack coats, and chip-seal prime coats. A single truck can cover 15,000–30,000 m² per day depending on width, speed, and application rate.