Abstract: The apparatus comprises means for replaceable coupling thereof to a standard raise boring head for extending the effective cutting radius of the head. The apparatus comprises a raise boring head radius extension element which is pinned to struts extending from a circular hub; the hub, in turn, envelops a terminal end of the stem of the raise boring head. Additionally, pin-holed clevises borne by the extension elements mate with like pin-holed lugs which extend, radially, from the principal cutter bracket mounting platform of the standard raise boring head. Expansion pins are engaged with the lugs and clevises, and also secure the struts both to the hub and to the extension element, to simplify assembly and disassembly. In typical use, a plurality of radius extension elements are coupled to the standard raise boring head, the elements being arrayed circumferentially thereabout.

Abstract: In the embodiment shown, the coupling means comprises an annular wedge which is insertable between the stem and the cutterhead of a raise borer, the wedge being bolted to the cutterhead to effect contact pressure in order that rotary torque will be transmitted from the stem to the cutterhead. A thrust plate is secured to the lower end of the stem in engagement with a lowermost surface of the cutterhead. In addition, a friction locking assembly is used on an underlying or protected portion of the cutterhead to center and locate the stem relative thereto.

Abstract: The apparatus comprises means for coupling to a standard raise boring head for extending the radius of the head. The apparatus comprises a support which is bolted or welded to a terminal end of the raise boring stem and to the underlying surface of the principal cutter bracket mounting platform of the head, and the support has means for selectively coupling thereto cutter mounting extension elements each of which comprise ancillary cutter bracket mounting platforms.

Abstract: The raise boring head comprises a stem in which is formed a passageway which extends fully throughout the axial length thereof for conducting fluid therethrough. The uppermost end of the passageway defines an inlet and, at the lowermost end, the same comprising an outlet, a coupling is fixed to receive threaded fitting elements for use to control and/or direct fluid flow from the outlet or axial end of the passageway. By this means a spray nozzle, as disclosed in one embodiment, can be threaded into the coupling to direct a conical spray of water onto the walls of the bore in order to suppress dust. In alternative embodiments, hose or like conduits can be used in operation with the passageway to facilitate the use of hydraulic, electrical, or pneumatic tools and devices in a subterranean chamber or tunnel below the raise.

Abstract: The arrangement comprises an earth raise borer stem which is formed with a tapered surface, near one terminal end thereof, for slidably engaging and forming an interference fit with a similarly tapered collar within the center of a cutterhead. The stem further has, at the lowermost end thereof, according to one embodiment, a bolted-on flange plate which has a series of rectangular cutouts formed therein. The cutouts receive lugs which are also bolted onto a lowermost surface of the cutterhead. The cooperating tapered surfaces of the collar and the stem cooperate to react thrust and torque which is impressed through the stem to the cutterhead and the cutout flange plate impresses rotary torque onto the cutterhead by means of the lugs. The arrangement provides a simple and facile arrangement for replaceably coupling a stem and cutterhead.