Tunnelling or heading shield beam cutters round the periphery of the shield canbe pressed forward singly or in groups and terminate forward in ramp cutters to achieve the heading work. The individual cutter beams (10) on the shield have each a cutter plate (12) which can be adjusted parallel to the ramp cutter (11) by means of a setter (16-19) in amounts shown by the device as an indication of the radial attitude (R) of the plate and thus the clearance cut of the shield unit. Preferably the angle of the cutter ramp (11) is such that the angular displacement of the cutter plate (12) is twice its radial displacement capacity (R). The rear end of the plate should serve as the measuring edge which indicates the degree of radial extension or outward movement exhibited by the plate.
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