Dynapac Compaction Equipment has introduced the "Oscilla-Tech" vibratory drum system for its CS1400 and CS1800 series tandem asphalt rollers. In urban road rehabilitation, paving a thin layer of new asphalt (screed leveling course) over an old, flexible asphalt base is challenging. Traditional single-shaft vibratory rollers deliver a vertical impact force. On thin layers over flexible bases, this vertical force creates a "standing wave" (resonance) in the asphalt, causing the drum to bounce off the surface. This "drum bouncing" not only leaves a wavy, unsmooth surface but also crushes the aggregate in the thin asphalt layer, leading to premature road failure.
The Oscilla-Tech system replaces the single eccentric shaft with a "Dual Counter-Rotating Eccentric Mass Assembly" housed within the drum. The engineering innovation is the "Tangential Force Vector Generation." Because the two masses rotate in opposite directions at the same speed, their vertical centrifugal forces cancel each other out perfectly. The remaining force is a pure horizontal (tangential) "push-pull" motion.
Instead of violently slamming the asphalt downward, the drum gently kneads the asphalt forward and backward. This horizontal shear force effectively closes the voids in the asphalt mix without destroying the aggregate skeleton or bouncing off the flexible base. Furthermore, the system features "Intelli-Transition Logic." When the roller approaches a cold joint (the edge of a previously paved lane), the system automatically reduces the phase angle between the two masses, dropping the compaction force by 50% to prevent shoving or cracking of the cold edge. This horizontal compaction technology increases the density of thin asphalt layers by 15% while completely eliminating drum bounce and surface waves.
