Small milling machines (milling width < 1 m) are mostly wheeled machines. Depending upon the machine type, they can mill up to a depth of 300 mm. The milling drum is arranged at the rear of the machine, enabling them to mill flush to obstacles at the rear and in a transverse direction to the pavement.
Large milling machines (milling width > 1 m) are equipped with crawler track units and a loading device (conveyor system) as standard features. Depending upon the type of machine, they have milling depths of up to 350 mm. Within these machines, the milling drum is arranged at the centre, between the front and rear crawler tracks.
A common feature of all milling machine is their milling drum. It works in an up-milling direction, that is, it rotates in anti-clockwise direction, scarifying the asphalt from the bottom upwards. The milling drums are equipped with rotating point-attack cutting tools and are firmly connected to the machine frame. The height adjustment, and thus the adjustment of the milling depth, is effected by adjusting the height of the lifting columns, which are connected to the machine's crawler track units or wheels respectively.