Longwall mining[1]
- 2. GENERAL DESIGN • Machine body containing electric motors,hydraulic equipment and controls mounted over Amoured face conveyor • Horizontal cutting drums are mounted on the face side of the machine,laced with cutting picks and rotating in a plane parallel to face • Hydraulic roofs installed for support
- 3. DESIGN
- 4. PRINCIPLE OF OPERATION Working under the steel canopies of hydraulic, movable roof supports, a shearer runs back and forth along the face,taking a cut during each pass. The cut coal spills into an armored chain conveyor running along the entire length of the face. This face conveyor dumps the coal onto belt conveyors for transport out of the mine. As the cutting machine passes each roof support, the support is moved closer to the newly cut face to prop up the exposed roof.
- 5. POWERING MECHANISM • . To move the machine, up to four electrically powered main motors are used • Each motor is operated by a gear unit and a gear wheel engaging with a lantern wheel, a type of chain. • Hydraulic power is used for hydraulic ranging arms • Hydraulic power for roof supports
- 6. TYPES • Double drum ranging shearer • Single drum ranging shearer • Single drum fixed shearer • Plows
- 7. APPLICABILITY • Double drum ranging shearer are used in thick seams • For less than 52 inches of clearance,single drum machines are used • Plows are used in thin seams
- 8. SAFETY FEATURES • Emergency stop switch • Automatic pre start warning devices • System which automatically stops haulage in case of over tensioning of electrical supply cable • All operating controls for systems powered hydraulically shall be designed to automatically return to the "OFF" position on loss of pressure, to avoid inadvertent start-up when the electrical power supply to the shearer is energised