3 86 MINING 



motor, either geared or direct-coupled to the drum shaft, with rheostatic control, and, 

 in the other, a direct-current motor, on the Ward-Leonard system, with the use of a fly- 

 wheel accumulator. The field of the former has been greatly extended by the introduc- 

 tion of efficient and durable machine-cut helical gearing. 



The Brown-Boveri system, installed at the Heinitz Colliery, Upper Silesia, comprises 

 the conjunction of high-pressure turbine, Ward-Leonard generator and A.C. generator, 

 the turbine having considerable -overload capacity by means of relay-operated by-passes if 

 necessary, the A.C. generator supplying the general load of the colliery or as much of it as it 

 can, and the Ward-Leonard generator the winding-engine. Another system is the series 

 system, due to Prof. Thury. 



The three-phase commutator motor has also been advocated for work of this description. 

 Two types of such motor are obtainable the series motor and the double-repulsion motor. 

 In both cases speed regulation is obtained by brush displacement. 



In 1911 a valuable report was issued of trials carried out by a joint committee appointed 

 by the German Engineers' Association, the Dortmund Mining Association, and German 

 Boiler Inspection Association (Gluckauf, Nos. 42 to 52, 1911). The trials were carried out 

 with the electric winding plants at the Deutscher Kaiser, Rheinelbe, Mathias Stinnes and 

 Emscher-Lippe collieries; and with the steam plants at Schiirbank and Charlottenburg, 

 Julia, Helene and Amalie and Wilhelmine Victoria collieries. The report states that on 

 general principles the working of a steam engine is the more satisfactory, as the mean net 

 load approaches that for which it was built; and therefore the smaller the load the lower the 

 efficiency. The electrical winder however adapts itself better than the steam engine to 

 reductions in the net load. It cannot be deduced from the different values obtained that 

 any given type or either of the forms of energy is unconditionally the best in general. In 

 deciding which method of winding is to be preferred, the prime cost, depreciation and upkeep, 

 must be borne in mind, as well as the consumption of steam or energy; and, in addition, how 

 the method fits in with the general working conditions of the colliery. 



At the Great Western colliery the Westinghouse winder on the converter-equaliser 

 system is capable of raising 25 tons of coal from a depth of 1 1 10 ft. in 37? sees, at a speed of 

 70 winds or 175 tons per hour. The maximum shaft speed is 40 ft. per second and at full 

 work the winder requires 4.8 units per wind. 



Considerable improvements have been effected in the steam winding-engine, and the 

 large compound condensing engines installed within recent years represent a high efficiency. 

 A notable economy has been obtained from the utilisation of exhaust steam in mixed pressure 

 turbines, with or without accumulators on the Rateau principle: examples of such instal- 

 lations are to be seen at the Hulton, Maypole, New Hucknall and other collieries. They are 

 very suitable for driving large compressed air plants in connection with coal-cutting machines, 

 where it is not desirable to take electricity to the face of the coal. Tests at the Konigsborn 

 mine at Unna-Konigsborn in the Dortmund district have shown that when working with 

 low-pressure steam having an initial pressure of 1.2 atmosphere and a final pressure of o.l 

 atmosphere, 2\ Ibs. of steam are used for every cubic metre of free air compressed; and \\ Ib. 

 when working with fresh steam having an initial pressure of 7 atmospheres and the same 

 final pressure of o.l atmosphere. At Penallta colliery in South Wales, the sinking engine? 

 were fitted with throttle valves on the high and low pressure cylinders, to obtain a starting 

 torque equal to a pair of engines without the admission of live steam into the low-pressure 

 cylinders. The engines were designed to wind from a depth of 800 yds. in 45 sees. 



The provisions in the British Coal-Mines Act in regard to shafts and winding have entailed 

 considerable alterations in the equipment at many collieries. After the beginning of 1913 

 every vertical shaft is to be provided with a detaching hook, and where more than 100 yds. 

 in depth, with an effective automatic contrivance to prevent overwinding. Detaching hooks 

 have been in common use at British collieries for many years; overwinding controllers, how- 

 ever, have been employed in but few instances, although many of the largest Continental 

 mines are equipped with them. Generally speaking, these gears are mechanical contrivances 

 which automatically cut off steam and apply the brakes when the limits of speed are exceeded 

 at certain points in the shaft, or in cases where the engineman starts his engine the wrong 

 way in the shaft. During 1912 numbers of these gears were invented. Some of the best; 

 known of those used in British mines are the Barclay, Whitmore, Wilde & Petrie, " Visor, '* 

 Shaw, Wallace, Jackson & Staley, "Profile," Melling, Futers Daglish, Walker and Inglis 

 controllers. In France the principal types are the Reumaux, Sohm & Burg devices. 



The same section of the Coal-Mines Act provides for the use of guides in sinking shafts, 

 and of "kens" at the surface, the periodical capping and limited employment of winding 

 ropes and the equipment of cages with catches, covered tops, gates and hand bars. 



The new French regulations draw a distinction in the testing of winding ropes, in respect 

 of the numbers wound at a single journey. Where more than four persons are wound in the 

 shaft at the same time the ratio between the resistance to rupture by tension and the total 

 load must at least correspond to the factor of safety. The rope is to be discarded when the 

 loss of resistance exceeds 30 per cent of its original value, and no winding rope may be used 

 for a load greater than one sixth of its breaking strain, if of wire, or one fourth if of hemp. 



