Mining apparatus is disclosed in which a cutting wheel (36) supporting a plurality of roller-cutters (44) rotates about a horizontal axis and is supported on a slewing boom (17) for cutting a tunnel with a flat floor (80) and roof (81) and elliptical walls as it slews across a mining face. The slewing boom is supported on a main beam assembly (14), the front end of which rests on powered crawler tracks (60) and the rear end of which passes through a gripper assembly (24) which may be clamped between the floor (80) and roof (81) of the tunnel, and against which the main beam assembly (14) may be urged forward for engaging the roller-cutters (44) with the mining face. A preload crawler (22) is urged against the roof (81) of the tunnel above the powered crawler tracks (60) to locate the main beam assembly (14) rigidly relative to the tunnel such that the roller-cutters (44) may cut the rock in the mining face with minimal loss of cutting force due to vibration.