Cutting drum for an open cast apparatus performing its winning action in both directions of travel

A milling roller for a self-propelled mining device performing mining in both directions of travel for strip mining, the milling roller comprising:

• milling tools;
• a ring;
• cutter bars on the milling roller circumferential surface said cutter bars being connected to one another in a circumferential direction by said ring and carrying said milling tools, each milling tool including bits with bit holders, said bit holders being mounted tiltably around an axis of rotation for automatic tilting such that bits pointing in a direction of rotation are automatically pivoted into a milling position by the digging resistance during engagement with the material to be mined, and that the bits directed in the opposite direction are at the same time pivoted out of the range of the free-cutting angle of the bits performing the digging operation, one of said bit holders being positioned for milling operation with rotation to the right and another bit holder of said pair being positioned for milling operation with rotation to the left, arranged on both sides of a said cutter bar in a hinge-like manner, said bit holders being connected by carrier plates, said bits being interchangeable bits fastened to said bit holders, said carrier plates including blades in an area of tips of said bits;
• connection bars between said milling tools, said connection bars being arranged opposite said cutter bar for effecting said automatic tilting;
• and
• catches provided at said connection bars for fixing said bits in the respective digging position or free-cutting position with a force that is strong enough to prevent said bit holders from tilting under their own weight during rotation of the milling roller, whereby at the time of a change in the direction of milling, said bits of one cutter bar side are moved upon contact, of said bits of said one cutter bar side and an associated said blade, with the mineral to be separated against the force of said catches and opposite bits are pivoted into the free-cutting position.