Abstract: A vacuum system is mounted on a portable milling machine for extracting material cut by the milling drum of the machine from the surface of a roadway. The milling machine includes a frame, a propulsion system for advancing the machine across a surface to be milled, a milling drum mounted on the frame for rotation about its axis, and a conveyor for conveying material cut by the milling drum away from the drum. The vacuum system includes a vacuum pump having an air inlet and an air outlet and a nozzle mounted behind the milling drum having an opening for receiving material cut from the surface by the drum. The vacuum system also includes a material collector having an inlet, an air outlet and a material outlet. The collector is adapted for collecting material entrained in air by the pump through the collector inlet and for discharging such material through the material outlet onto the conveyor. The vacuum system also includes a first conduit and a second conduit.