A highway paving contractor reported that a Vögele SUPER 1800-3i asphalt paver's screed was producing an inconsistent finished mat surface. Sections of the mat behind the screed showed visible tear marks and a rough, open texture, particularly along the right half of the mat. The left half appeared normal. The operator also noticed that the screed's temperature gauge was reading erratically, jumping between 120°C and 160°C even at a steady operating condition.
The technician first recognized that the screed's heated plates must maintain a uniform temperature of approximately 150°C to prevent hot mix asphalt from sticking to the screed plate and tearing during the paving operation. He used an infrared temperature gun to measure the actual screed plate temperature across its width. The left side measured 150°C (correct), while the right side measured only 95°C-well below the required temperature.
He then inspected the "Screed Heating System." The SUPER 1800-3i uses electric resistance heating elements embedded in the screed plates, powered by the paver's generator. He traced the heating circuit to the "Screed Heating Junction Box" mounted on the screed frame. Upon opening the junction box, he found the interior packed with wet asphalt residue and green corrosion on the terminal connections. Two of the four heating elements' terminals had completely corroded through, creating an open circuit-these two elements were receiving no power and therefore producing no heat. He further discovered a failed "Screed Plate Thermocouple" on the right side. The thermocouple was reading an artificially high temperature due to internal corrosion, which was confusing the temperature controller into reducing power to the right-side heating elements, exacerbating the underheating.
The root cause was traced to a damaged junction box gasket that had allowed water and asphalt dust to ingress during recent rain-day operations. The corrosion had progressively degraded the connections over several months.
The repair involved replacing the complete screed heating junction box with a new sealed unit, replacing the corroded heating element terminals with new nickel-plated connectors, and installing a new right-side screed plate thermocouple. The heating circuit was tested with an ohmmeter to verify consistent resistance across all four heating elements. After reassembly, the screed plate temperature was uniform at 150°C across its full width, the temperature gauge displayed stable readings, and the finished mat surface showed no tear marks or open texture.
