Patent GB-297137-A (GB)
Title: Improvements in or relating to excavating or boring apparatus
IPC: E21D9/10
Filed: 1927-06-14
Abstract: 297,137. Francois Cementation Co., Ltd., Degenhardt, W. R., Fraine, A. F. de, and Bicknell, R. A. W., and Bicknell, A., (Representatives of Bicknell, R. H.). June 14, 1927. Digging apparatus.-In an excavating, tunnelling or shaft sinking apparatus of the automatically controlled type described in Specification 238,262, wherein an abrading tool is mounted on a universally-pivoted arm and is moved so as to act on all parts of the working face, the tool is so guided that the product of its linear velocity and active area is approximately constant so that an approximately constant volume of material is removed per unit of time. Preferably the active area of the tool is constant and the velocity approximately constant. As shown, a wheeled frame A carries brackets B<2> in which a traversing arm B is universally pivoted, the arm B carrying a cutter B<3> operated percussively by liquid-wave transmission ; the liquid is supplied from generators C, on a separate truck C<2>, through pipes C<3>, C<4>, C<5>, C', C<6>, the pipes C<6>, C', being arranged to pivot about axes aligned with those of the universal mounting of the arm B. The arm B is balanced by a counterweight B<4>, preferably built up of lead disks, and has at its rear end a ball-shaped member B<5> engaging a socket D, Fig. 6, in a block D' slidable in radial guides in a rotary member D<3> carried by a tubular shaft D<2x>, while the block D<1> engages a crank pin D<4> on a disk D<5> carried by a shaft D<5x> ; the member D<3> is driven from a motor D<8> through belt gearing and worm gearing D', while the crank disk D<5> is driven through differential gearing d<3>, d<3x>, d<5x>, d<5>, whereby the cutter B<3> is given a spiral motion. A clutch may be provided between the gears d<3>, d<5> whereby either gear may be engaged with the shaft D<5x>. The linear velocity of the cutter is maintained constant by means of gearing d<9x>, Fig. 11, driven with the member D<3> and driving a disk D<10> which, through a connecting rod d<9>, moves a belt D<9> on tapered pulleys D<9x>, D<10> through which the drive is communicated from the motor D<8> ; alternatively, the rod d<9> may control a variable resistance by which the speed of the motor is varied. A rearward extension of the shaft D<5x> acts through worm gearing E<1>, E<2>, to drive a cam E<3> which, after each half cycle of the arm B, acts through a lever E<4>, pawl levers E<5>, ratchets E', and pinions E<8> to drive pinions E<8x> engaging racks, whereby the machine is advanced. Debris is removed from the working face by a scraper G carried by a frame G<1> which is reciprocated through a lever G<5> from a cam G<4> moving with the member D<3>, the mechanism being turned so that the scraper always clears the tool B<3> ; the frame G<1> has rollers cooperating with pivoted inclined members G' whereby the scraper is lifted over the debris in its forward stroke. The scraper delivers to a sectional conveyor comprising hinged plates F carried by reciprocating members F<1> driven from a motor F<2> through a belt F<5>, reducing gearing and a connecting rod F<4>. The tool comprises annular edges b' divided by radial and diametric grooves b<3x> of variable depth the grooves being continued so that peripheral cutting edges B<3x> are formed. During operation, shocks are taken up by toggles Ex engaging the. turnel wall. The cutter may operate in circular paths, being moved radially after completing each circle. Other than circular tunnels may be formed; to form elliptical tunnels, the machine may act at an angle to the direction of the tunnel.