Abstract: Feed frame assembly for supporting and feeding drill head which rotates drill rod about axis. Assembly includes spaced front and rear end members, laterally spaced longitudinal members and first and second hydraulic feed cylinders. Longitudinal members and feed cylinders extend between end members and are parallel to rod axis. Piston rods of feed cylinders have double-acting pistons cooperating with cylinder bodies to feed head along the piston rods. Stabilizer cylinders in longitudinal members force bearing pads against rock face to counteract the drilling forces. Head mounting means secures rigidly one side of drill head to first cylinder body, and secures releasably with latch opposite side of head to second cylinder body. When latch is released drill head can swing outwards about first piston rod, and when engaged mutual actuation of feed cylinders moves drill head along rods. With head swung out, first cylinder is hydraulically locked to divert fluid to second cylinder.