Patent GB-162696-A (GB)
Title: Improvements in or relating to tunneling machines
IPC: E21D9/10
Filed: 1919-11-03
Abstract: 162,696. Hencken, J. K. Nov. 3, 1919. Tunnels ; tunnelling by boring. - A tunnelling-machine with centrifugally-operated cutting hammers comprises a rotary head forming an enclosing shell and having a front closure provided with an opening through which the hammers operate, the latter being disposed along a transverse shaft. The machine shown comprises a rotary head supported by roller bearings 31 in front of a shield 65 closed by a bulkhead 67 provided with doors and with a ball-bearing support for the central member 25 which is driven through worm gearing 23, 24 to rotate the head; the member 25 has annular conduits 32, 33, &c. for the passage of air, water, cement, &c. to the rotary head. The latter comprises a cylindrical shield 29 and a breast shield 15 with adjustable roller supports 22; the breast shield has a transverse slot through which centrifugal hammers 10 attack the tunnel breast, these hammers being carried by a transverse shaft 6 rotated by a motor arranged near the centre of the shaft. Further centrifugal hammers 10 operated by a motor 19 attack the periphery of the tunnel, the cuttings therefrom passing through a pipe 20 to the casing 16 of the transverse set of hammers. The hammers may cut the whole breast of the tunnel or may cut concentric grooves, the ridges left between the grooves being cut away by two reciprocating saws 104 : one saw is driven from the motor 19 and the other by gearing operated by rotation of the head. Water supplied to the breast through a pipe 38, and air exhausted from the motors, pass through the hammer casing 16 and carry the cuttings through a screen 21 to the discharge pipe 17. The shield 65 is provided with carriages 49 spaced circumferentially and each containing supporting means 53 for roller chains 52, which are simultaneously driven through chain gearing 57 and engage the tunnel wall to advance the machine: the supporting means 53 are adjusted by hand wheels 61, 63 when the direction of the tunnel is to be changed. As the boring proceeds the tunnel is lined, the lining comprising an outer layer of asphalt or fine concrete, followed successively by a layer of steel ribbon 73, Fig. 10, coiled around the tunnel wall and with contacting edges of adjacent coils interlocked, a further layer of fine concrete or asphalt, a layer of plain steel ribbon coils 74 all laid in front of the shield 65, spaced longitudinal ribbons 86 laid by the chains which advance the machine, and a final layer of coarse concrete 88 laid around the reduced rear end 93 of the shield 65 which forms a centering therefor. The steel ribbons pass through a central conduit 71, Fig. 1, provided with gaskets 27 for preventing leakage, and over rollers 75, 76, Fig. 3, driven by pinions 78, 79, engaging a circular rack 80 on the shield 65, the ribbons being tensioned and straightened by spring-pressed rollers; the layers of fine concrete or asphalt are laid by pipes 84, Fig. 3, surrounded by electric heater coils when asphalt is used. The coarse concrete is made and laid by the plant shown in Fig. 1a. The conduit 17 for the excavated material, air, and water has branches 39, 41 leading to receptacles 40, 42 connected by conduits 200, 201 to a pump 201a leading back to the conduit 17; the stronger draught is provided in the. conduit 39 whereby sand is drawn through a pivoted sieve 46 to the receptacle 40. A pivoted screen 47 partially closing the conduit 17 guides coarser debris into receptacles 42. Self-acting gates close the receptacles 40, 42 when full. The sand and coarse material is then passed, with cement from a receptacle 45, through valve-controlled conduits 43, 100 to one of two concrete mixers 44. Air admitted to the mixers by a pipe 89 agitates the concrete and also forces it through pipes 85, 91, 92 to form the inner lining. The rear of the shield is provided with cores 98, 99 to form conduits for drainage and wires, and with steam jackets 95, 96 to assist in setting the concrete; the inner lining is also lubricated by paraffin &c. passed through pipes 97. The centrifugal hammers comprise inner arms 9, Fig. 7, carrying pivoted angular arms 10a on which the hammers proper 11 are mounted; these may be of suitable polygonal form with similar openings 12 through which the pivot pins 13 pass, these pins having ends of similar polygonal form which, with pins 13a, lock the hammers 11 in place. The arms 10a may be reversed, each end having a pivot 13. Circular &c. hammers may be used. If the bore of the tunnel becomes reduced, a roller, engaging the tunnel wall and carried by a spring- pressed rod 120, Fig. 1, operates a switch 122 to give an alarm. If the tunnel breast is cut unevenly, the resulting vibration operates a switch 126 carried by the bulkhead 67 to give an indication. An alignment indicator comprises a wire normally passing centrally through an eye but contacting with the side thereof, to close a circuit when the machine is diverted. It is also stated that the machine may be advanced by the pressure exerted in grouting behind the shield.