GB129013A - Improvements in Earth-boring Apparatus. - Google Patents

Abstract

129,013. Lea, E. C., and Orlebar, B. O. C. Sept. 20, 1917. Tunnelling by boring. -An earth - boring machine, more particularly for forming military tunnels or passages, comprises a cylindrical casing 1, a cutting-head 2 driven by a motor 3, a central nut 5 for feeding the casing and head forward, and anchoring-. struts 4 extending radiallv from the nut and adapted to be projected through longitudinal slots 6 in the casing and into the surrounding earth to prevent longitudinal movement of the nut and rotation of the casing. The struts comprise telescoping parts 4<a>, 4<b>, the parts 4b being connected by links 7 to a toothed disk 8 which is rotated by a pinion 10 to project or withdraw the struts. The links 7 may be adjustable, or the parts 4<b> may carry a relatively adjustable outer part. Two sets of slots 6 are provided, the struts being angularly adjusted after each advance of the machine so as to obtain a better purchase on the earth. The cutter head 2 is slightly conical and comprises arms 13 and a rim carrying reversible double-edged cutters 14; the head is connected to the casing by angle rings 15, 16 enclosing two sets of bearing-rollers 17, 17a, Fig. 5, on axes at right-angles to each other, the rollers being supported by a cage formed of two angle rings 18. The axle 19 of the cutting-head is threaded to engage the nut 5, and its rear end is supported in a spider 21. The motor 3 is suspended from the axle 19 and is prevented from rotating by means of a hooked bracket 23 on the casing 1. To permit a slow feed to be obtained while using a coarse thread on the axle 19, the nut 5 is rotated from the axle through gear-wheels 29, 28 which are normally held in mesh with wheels 26, 27 by a spring catch 31, but may be moved on the spindle 30 to enable the nut to be advanced by hand. The cutter head and casing may each be in three or more sections, and the cutter head may have a central conical portion projecting forwardly. To relieve the floor below the casing and so facilitate horizontal boring, the machine may be connected to a lever 32, Fig. 8, carrying a balance-weight 34 and provided with a fulcrum in the form of a roller 33 which runs on a track 37 yieldingly carried in a frame 35 by a spring 38, Fig. 9; the spring is supported by a carriage 39 which may be adjusted by screws 41 resting in bearings 43, which are themselves adjustable. Ball bearings 49 and load-indicating means 46 also are provided. The spoil may be removed by a screw conveyer 101, Fig. 11, driven from the motor 3 and supported in a casing 102 connected to the spider 21. A mouthpiece 105 collects the spoil. A bucket or chain conveyer may replace the screw. The ca.sing 102 of the conveyer may replace the lever 32, Fig. 8.