A crawler track mounted mining machine having a frame and an adjustable jib
carrying an endless cutting chain having cutters and loading flights
mounted on the frame. A bridge on the frame and spaced arms having one end
pivotally connected to the bridge and the other end supporting a front
plate upon which the jib is adjustably mounted by a rotatable bearing
supporting a cross member which carries hinges pivotally supporting the
jib. Hydraulic rams extend between the cross member and the jib to rotate
the jib between a vertical position and a horizontal position and a
hydraulic ram extends between the rotatable bearing and the front plate to
rotate the front plate and the jib in a horizontal plane between a
position perpendicular to the crawler tracks and a position parallel to
the crawler tracks. Hydraulic rams extend between the bridge and the arms
to raise and lower the arms and the jib relative to the frame.