Abstract: A musical instrument of the stringed kind having a hollow sound box formed of a top plate, bottom plate and side walls. A string supporting bridge is mounted on the top plate and has two feet which are spaced apart transversely of the instrument. A sound post extends between the top and bottom plates and is connected to one foot of the bridge through an opening formed in the top plate. The opening and the connection are related so that there is no impediment to movement of the top plate in the region of the opening. By way of example, the post may extend through the opening to effect the connection with the bridge foot, in which event clearance will be provided between the post and the opening.

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

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

Abstract: A mobile mining machine for cutting a tunnel in rock has a wheel-like cutterhead assembly supported by a pitch boom assembly that causes movement of the cutterhead assembly in the vertical plane. A swing boom assembly supports the pitch boom assembly and is supported by the main frame of the mobile mining machine. In one embodiment the swing boom assembly has a pivot axis that is tilted from vertical and swings the cutterhead and the pitch boom during mining to cut a tunnel having a wide, flat floor. During mining, a gripper assembly having a floor gripper shoe and a roof gripper shoe brace the mobile mining machine in the tunnel. Thrust is provided by thrust cylinders located between the gripper shoes and the main beam. Extension of the thrust cylinders moves the cutterhead assembly, main beam, and rear portion of the mobile mining machine forward relative to the gripper assembly due to slidable engagement of the main beam and gripper assembly.

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

Abstract: A mobile mining machine for cutting a tunnel in rock has a wheel-like cutterhead assembly supported by a pitch boom assembly that causes movement of the cutterhead assembly in the vertical plane. A swing boom assembly supports the pitch boom assembly and is supported by the base frame of the mobile mining machine. The swing boom assembly causes movement of the cutterhead assembly and the pitch boom assembly in the horizontal plane. During mining, a fixed front support and a fixed rear support anchor the mobile mining machine in the tunnel with front and rear crawlers raised from the tunnel floor. During re-gripping, the front and rear crawlers are lowered to support the mobile mining machine and the fixed front support and fixed rear support remain in contact with the tunnel floor. During tramming, the front and rear supports are raised for transportation of the mobile mining machine on the crawler.

Abstract: A shaft boring machine including a rotatable cutterwheel assembly with a horizontal axis mounted on a carriage having vertical travel. The carriage is mounted on a slewing base frame and rotates about the vertical axis of the machine. An excavating unit for muck removal is mounted opposite the cutterwheel on the slewing base frame and loads directly from the shaft bottom into a muck hopper. When the hopper is full, it is discharged into a hoist bucket which is hoisted to the surface. The machine is positioned in the shaft by upper and lower gripper systems. Walking cylinders between the two gripper rings advance the machine up or down the shaft.

Abstract: A tool assembly (4) for working a material (R) such as breaking rock. Assembly (4) includes a tool mounting (17) having a fixed section (18), and a movable section (19) for movement relative to the fixed section (18) in a working direction (D.sub.W) and an opposite return direction (D.sub.R). A tool (34) is mounted on the movable section (19) for movement relative thereto in the working direction (D.sub.W) and return direction (D.sub.R). Limit means (49,50) on tool (34) limits relative movement between tool (34) and movable section (19) to between a tool operative position and a tool operated position. During a working stroke, tool (34) is engaged with material (R) and moved in working direction (D.sub.W) from the operative position to the operated position and thereafter in unison with the movable section (19) under action of a working force applied to tool (34) thereby to work material (R).

Abstract: A first mobile mining machine for cutting mining tunnels in hard rock, which includes a horizontally swinging wheel-like cutterhead assembly mounted on a crawler and base frame assembly. The cutterhead assembly consists of a transverse horizontal axis wheel-like drum on which are multiple peripherally mounted rolling cutter units.A second mobile mining machine for cutting mining tunnels in hard rock, which includes a horizontally swinging and vertically ranging wheel-like cutterhead assembly mounted on a crawler and base frame assembly. The cutterhead assembly consists of a transverse horizontal axis wheel-like drum on which are multiple peripherally mounted rolling cutter units.

Abstract: A bit connectible from the lower end of a rotatably powered drill stem for enlarging a preformed pilot hole includes a cutter carrier frame on which are mounted a plurality of roller cutters having peripheral cutting edges which sweep concentric circles upon rotation of the raise drilling bit. The circles swept by the cutters collectively define a generally dome-shaped cutting profile of constantly changing curvature which forms a segment of a spiral curve so that as the cutting profile extends radially outwardly from the drill stem, its curvature progressively decreases. The rotating cutter carrier frame structure drives a flywheel assembly at increased speed through the intermediacy of a step-up drive system composed of two planetary gear drives coupled in tandem.

Abstract: A cutter wheel is mounted at the lower end of the machine for rotation about a horizontal tubular support. Cuttings are picked up by buckets on the cutter wheel and are directed into the tubular support to be received by an endless bucket conveyor which carries them upwardly to a discharge station. As the machine is advanced the cutter wheel is rotated to make a first cut in the shape of the leading portion of the cutter wheel. The cutter wheel is then retracted out from the cut and is rotated about the axis of the hole. This repositions the cutter wheel so that when it is advanced again it will make a second cut which crosses the first. This procedure is repeated until the desired cross-sectional configuration (e.g. circular) of the hole is obtained.