Abstract: A rack assembly for allowing movement of a winning machine utilized in underground, long-wall mining operations. The rack assembly is comprised of a plurality of rack sections positioned end-to-end and suitable for attachment to trough sections of a face conveyor. The rack sections correspond in a one to one relationship to the trough sections and have lengths slightly greater than the associated trough sections. Toggles connect adjacent rack sections and maintain the adjacent rack sections such that end faces of the rack sections are maintained contiguous to one another, preventing relative longitudinal movement between the adjacent rack sections. The toggle, however, allows limited, relative vertical and horizontal movement between adjacent rack sections to allow positioning of the rack sections along a mine floor.

Abstract: The invention is particularly adapted for use with a longwall mining machine of the type having a rack extending along a track for the mining machine, a gear wheel on the machine engageable with the rack for moving the machine along a track, at least two shearer drums carried by the machine, at least one driving motor on the machine, and gear train means connecting the driving motor to the shearer drums to rotate the same. Two inductive clutches having a common armature are connected through reduction gearing to the aforesaid driving gear wheel; while separate rotors connect the respective clutches to the gear train such that one rotor will rotate in a direction opposite to the other. A magnetically-actuated, spring-biased friction brake is disposed between the two inductive clutches for braking the clutches when the machine is at rest.

Abstract: A track and gear rack disposed on one side of a face conveyor for a longwall mining machine and adapted to be engaged by a driving gear and guide wheels on the mining machine, the track and gear rack being of generally L-shaped cross-sectional configuration and having a horizontal arm resting on the mine floor and a vertical arm secured to the face wall of the conveyor. Driving pin extensions extend outwardly from the vertical arm in cantilever beam relationship near the upper edge of the vertical arm and have vertical widths less than the height of the vertical arm. One of the arms of the L-shaped configuration is provided with studs which engage guide block means on the mining machine for guiding it along the track and gear rack. The invention facilitates good guidance of the mining machine along the track and gear rack without impeding the flow of mined material onto the face conveyor.

Abstract: A gear rack for a longwall mining machine characterized in having a width permitting the arms which carry the cutter drums of the mining machine to move to lower positions relative to a face conveyor such that low seams of coal may be mined. The rack comprises a plate extending along the face conveyor and has driving pin extensions which extend from one face of the plate to engage a driving gear or gears on the mining machine.

Abstract: A method for securing mining machines, particularly longwall mining machines from sliding on inclined or steep seams in the event of a malfunction of a traction element or driving unit. The invention has particular application to longwall mining machines provided with at least two gearwheels which engage a rack extending along a working face whereby the mining machine may be advanced during a mining operation. The invention also relates to apparatus for automatically braking such a mining machine in the event of failure of a traction element.