Dynapac Compaction Equipment has introduced a hybrid "Oscillation-Vibration" system for its CC4200 and CC5200 series large tandem rollers. When compacting asphalt on bridge decks or thin overlay pavements, traditional high-frequency vertical vibration can cause "aggregate crushing" (breaking the stones) or damage the underlying bridge structure.
The new system allows the drums to operate in "Oscillation Mode" (horizontal shear force) or "Vibration Mode" (vertical impact force). The engineering breakthrough is the "Auto-Switch Logic." The roller is equipped with a "Ground Hardness Sensor" (measuring drum rebound acceleration). When starting compaction on a loose mix, the system uses "Vibration Mode" to drive the aggregate down. As the density increases and the sensor detects high rebound (indicating the surface is hardening), the system automatically switches to "Oscillation Mode."
This switch is critical because oscillation generates high shear stress without high vertical impact. It "kneads" the surface, sealing the top layer and creating a smooth, water-tight finish without crushing the stones. Additionally, the system features a "Gentle Bridge Mode." When the operator presses the "Bridge" button on the dashboard, the vibration amplitude is cut by 50%, and the frequency is locked to 40 Hz. This prevents resonance frequencies that could damage the bridge concrete girders. This intelligent adaptation allows the same machine to be used safely on both highway mainlines and sensitive bridge structures, increasing machine utilization rates.
