December 1, 1916. THE COLLIERY GUARDIAN. 1057 General Arrangement of Pit Top and Guide Rope Balance Weights. Fig. 12.—Interior of Engine House. Pit bottom Landing General Arrange- ment of Guide Rope Fastenings at Pit Bottom. have objections, has been in use for many years at some of the Great Western Colliery Company’s other pits. It has been found by actual practical experience that the ropes do not suffer any harm, and, as is well known, it is a very common practice in deep metal mines abroad. In any ease, the manifest advantages to be obtained in the use of a small diameter winding drum for a deep shaft more than compensate for any small deterioration of the winding rope which may result from the practice of over-coiling. Both shafts are fitted with guide ropes, the bottom ends of which a.re capped and fixed to strong girders across the pit. Their upper ends are secured by caps and clamps to a lever, with a fulcrum placed so as to give a proportion of about 4 to 1, whilst the other end is attached to a rope which is loaded with dead weights placed in square-sided recesses under the pit top land- ings, at a depth of about 40 ft., in which recesses the weights are encased and partitioned off from the shaft. The general arrangement of the pit top and method of securing the guide ropes of the upcast pit is shown in fig. 13. It will be noticed the guide rope clamp is supported in a cup-shaped recess in the arm, the bottom of the clamp being ball-shaped to suit, so as to allow the clamp to remain perpendicular as the lever rises or falls in consequence of the expansion or contraction of the guide rope. In the downcast pit, however, the arm is provided with a long bolt and swivel, as will be seen from figs. 14, 15, and 16, which shows the supporting lever in detail. The guide rope is secured in a “ Reliance ” gland or clamp, and is coupled up to the adjusting screw by a two-link chain and bow on the gland as shown. There are four guide ropes to each cage, and two intermediate ropes, as will be seen on reference to fig. 17, which shows a plan of the two cages in the 25 ft. diameter shaft. The cages for the Mildred pit are shown in detail in figs. 18 and 19. The hangers and hoops are made of channel sections, riveted together, and strengthened by gusset plates and angle bars. The guide shoes are fitted with brass bushes, and rubbing plates or fenders are fixed on the side next the intermediate guide ropes. As previously mentioned, the weight of the cage is 9 tons 10 cwt. There are six chains, which are secured to self-adjusting balance beams, and each of the six chains carries its proper proportion of the load. The complete set of chains and attachments, together with the rope cap, weighs 1 ton 9 cwt. The heavy load of 36 tons necessitated particular con- sideration as to the selection of a suitable type of capel, as this must be capable of withstanding a strain of 255 tons, which is the breaking strain of the ropes. The capel selected is one of novel design, patented by Mr. J. S. Sparkes, of Cardiff, and manufactured by Messrs. Geo. Cradock and Company Limited, of Wakefield. In principle it is an application of looping the rope round a thimble, with special arrangements for so doing and for holding the rope in that position when in use. It is also provided with a tightening wedge, by which the load on the rope increases the “ grip.” The chief claim made for it, however, as compared with other forms of removable capels, is that vibrations in the wires constituting the rope are not suddenly arrested at a fixed point in the capel, with the consequent liability to broken wires inside the capel itself. The rope capel, as well as the balancing arrangement for the cage chains, are shown in fig. 20. At the Mildred pit simultaneous decking is arranged for, there being two landings both at the top and bottom. The general arangement of the pit bottom landing is shown in fig. 20. The decking of the trams will be done by means of hydraulic rams, and the trams will be moved from the lower level to the upper, or vice versa, by means of creeper chains. At the upcast pit Berns' withdrawing keps are in- stalled, but at the other shaft, where the heavy load is to be dealt with, Davies’ patent withdrawing keps are used. These are shown in fig. 21. The arrangement is an improvement on the Beins’ keps, giving a better control when withdrawing, and, in this case, allowing a drop of from 6 in. to 7 in. before the kep is completely withdrawn from the cage. The formation of a double landing at the pit bottom necessitated large arches, these being 26 ft. wide by 22 ft. 6 in. high from the lower rail floor, as shown in fig. 22. The excavation was done in 5 yd. lengths, and heavily timbered with 12 in. square baulks, which were moved forward as each length was completed and the succeeding length com- menced. The lining is mass concrete, with a minimum thickness of 4 ft., reinforced with old guide ropes and 8 in. by 5 in. girder bent frames, which latter acted as “ forms ” when con- creting. As will be seen, a complete invert is formed. The flooring for the upper deck is formed of girders and concrete, 15 in. thick. A double inlet Sirocco fan, 15 ft. in diameter, capable of delivering 500,000 cu. ft. of air per minute at 6 in. water gauge, with an equivalent orifice of about 81'65ft., is coupled direct to a 700 horse- power Paxman-Lentz horizontal compound engine. The high-pressure cylinder is 20 in. diameter, and the low-pressure cylinder 32| in. diameter, the two cylinders being arranged in tandem with 32J in. stroke. The speed is 145 revolutions per minute. Provision is made for a second fan in the same engine house as a stand-by; but this will probably be electrically driven. In the engine house are also three quick-revolution air compressors, two of which are electrically driven and one steam driven. Of the two former, one by Messrs. Alley and MacLellan has a capacity of 1,200 cu. ft. of air per minute, and is driven by a 260 horse-power 2,200 volt motor at a speed of 290 revolutions per minute. The other is by the Tilghmann Sand Blast Company Limited, the capacity being 2,000 cu. ft. of air per minute; it is driven by a 400 horse-power 2,200 volt motor, also at a speed of 290 revolutions per minute. Both these compressors were used for supplying com- pressed air to the rock drills and pumps during sinking. The steam-driven compressor is by Messrs. Alley and MacLellan, the capacity being 5,000 cu. ft. of air per minute at a pressure of 100 lb. per sq. in. It is of their compound type, the steam cylinders being 32 in. and 48 in. diameter, the air cylinders 47 in. and 28jin., the stroke 15 in., and the speed 180 revolutions per minute. The screening plant is laid out for four picking bands, but so far only two have been installed. These bands’ or belts are 58 ft. long, including a radial loading arm of 20 ft. Each belt is 5 ft. wide, and is of the plate type, the plates being J in. thick. The coal is delivered from the tipplers, as is usual in South Wales, on to fixed bar screens, provided with “ Billy ” boxes which weigh the quantity of small coal passing through the bars. This weight is deducted from the workman. From the bar screens the coal is distributed on to the picking band by jigging shoots, whilst the small coal is dealt with on two canvas belt conveyors. A scraper conveyor carries the pickings and rubbish to a hopper on the high level, from which they are taken by trams to the rubbish tip. The plant is driven by three motors, two of 80 horse-power each and one of 30 horse-power. The two large motors are supplied with current at 2,200 volts, and the smaller at 440 volts pressure. The screen buildings are of struc- Fig. 13. is arranged with special _______________________, These give a large lighting surface, and the slope is such that no tural steel, and the roof A -shaped glazed lights, as shown in fig. 1. coal dust or dirt can accumulate on the inside. The writer is indebted to Mr. Hugh Bramwell, engineer and agent to the Great Western Colliery Com- pany Limited, for his kindness in supplying the infor- mation and detail drawings and photographs illustrating