July 3, 1914. THE COLLIEKY GUARDIAN. 37 HIGH TENSION IRONCLAD SWITCHGEAR, FOR MINING AND SUB-STATION WORK. Messrs. J. H. Holmes and Company, of Neweastle-on- Tyne, have favoured us with particulars of high tension ironclad switch gear, for pressures ranging from 2,000 to 6,000 volts, which they have specially designed to meet the demand of mining and consulting engineers for a safe, reliable, and spacious switch unit for high tension polyphase feeders in colliery and factory work. The carriage type oil switch, fitted with rollers and travelling on steel channelways, engaging with plugging contacts attached to the busbar chamber, has been adopted as giving the most convenient and quickest system of isolating—and many simple interlocks of very substan- tial build have been incorporated to render the gear thoroughly mistake and accident proof under every con- ceivable condition. The gear is totally enclosed to exclude moisture, coal dust, vermin, etc., the switch handle operating through a spindle in the switch case. The busbars are air insulated, with ample clearances to stand up on exceptional surges, and dust tight iron shutters automatically lock close over all the plugging contacts when the switch is drawn out of commission for inspection, etc., and the shutters are automatically raised again upon the switch being rolled into contact. Each unit is fitted with an internal oil tank lowering gear. An ammeter is included in the switch carriage when required, and cable boxes with armouring glands may be fitted in any position to busbar chamber. The switch will carry continuously 250 amperes at 6,000 volts, and will interrupt the circuit in a second under a good head of oil, on short circuit condi- Underground Locomotive Haulage Costs. By A. BAIJOT. From the Annales des In order to ascertain the relative economy of loco- motive traction in mines, it is necessary first to be acquainted with the cost of horse traction. Particulars obtained from a number of Belgian collieries show that the average cost of horse work per working day amounts to 6-75 fr., including food, interest on prime cost, depre- ciation, and driver’s wages. A horse will haul 32-14 ton- kilometres, the cost per ton-kilometre being 21 centimes; and will travel a distance of 13| kilometres, the mean load being 4| tons. The most important item of expense is the driver’s wage, which varies between 25 and 60 per cent, of the total; and the only way to economise in this particular is by employing boys, where the condi- tions are favourable, or working the horses, three in line, with a single driver. The output per horse-day might be increased by working longer trains and devising means for lessening the rolling friction of the tubs. Unlike the horse, the petrol locomotive does not cost anything except when at work, so that it is possible to increase the reserve stock of tractors without adding to the cost of haulage. When running, the cost per shift is not constant, since, on the one hand, the con- sumption of petrol varies with the work done; and, on Alines de Belgique. In comparing the cost of horse versus petrol engine traction, it may be assumed from the above data that one locomotive will do the work of 61 horses. On this basis the cost of hauling 212 ton-kilometres would be :— 6| horses. One locomotive Fodder (petrol) fr. 15-99 ... 9-23 Upkeep fr. 2-66 ... 1-72 Depreciation fr. 3-77 ... 5’05 Wages fr. 20-73 ... 9'86 Total per shift fr. 43-15 25'86 Tonnage per train .. tons 4-7 16-3 Mileage per unit ... kiloms. 13'250 ... 26-000 Work done per unit. .ton-kilom. 32-14 ... 212 These figures show a saving of 43-15 — 25-86 = 17-29 fr. (13s. 9d.) per shift in favour of the locomotive, assum- ing the latter to perform the work of 6| horses. The saving extends over all counts except depreciation; and the most striking improvement is in the amount of work done, which is not the least of the advantages of this form of haulage. The locomotive, however, does not always replace 61 horses exactly. In nine cases examined the ratio between the two systems varied between 1 : 4-07 and 1 : 10-4, the mean, however, being ' I . I Fig. 2.—Switch out of Commission and Opened for Inspection and Cleaning. Fig. 1.—Switch in Commission and Closed. tions, with a large power behind it. The handle of switch is loose, and cannot be held “ in ” on a fault, and access to switch contacts, tank lowering gear, trip coils, etc., can only be obtained by an authorised person hold- ing the key to the front plate, and only when switch is out of commission. Locks and interlocks are incor- porated in the gear, compelling that all making and breaking of current is carried out under oil under every condition, locking switch “ on ” or “ off ” whilst “ in ” or “ out ” of commission, which arrangement also includes a spring bolt locking the carriage on roller guides to guard against attendant accidentally pushing the switch into live contact during inspection, or unin- tentionally drawing the switch off the channelways alto- gether. The switch may be entirely removed on with- drawing the spring bolt. Interlocking of tank may be effected whilst in commission, the gear for lowering same being contained within the carriage—access being by front plate only. All the operations may be easily and safely performed by one attendant only. Fig. 1 shows a two-unit board with switch “ in com- mission;” fig. 2 showing the same board with one unit out of commission (drawn forward) and tank removed. The switch units may be fitted with indicating or inte- grating feeder wattmeters, as required, and the set may be added to in either direction. When required, they are also arranged to control main generators and fitted with synchronising gear, leakage indicators, power factor and frequency meters, etc., in which ease the exciter gear is controlled by an independent cast iron pillar with concentric hand wheels for operating alternator and exciter rheostats, field switch, ammeter, voltmeter, etc. The trifurcating boxes may be fitted in various posi- tions for the reception of incoming or outgoing cables to meet extraordinary conditions, such as obtain in posi- tions underground—where cables of large diameter and heavily armoured are used—and bends of small radius are therefore impossible. Mr. James Howden, of the firm of James Howden and Company Limited, engineers, Kinning Park, Glasgow, has left estate valued at £417,539. the other, the price of petrol fluctuates considerably. The horse-power of the engine is another source of varia- tion, but this factor is absent in the cases investigated by the author, all the engines being of 12-horse power. The following data form the average of 10 different cases examined :—Weight of petrol consumed per shift, 21-5 kilos.; cost of petrol, 37-81 fr.; per shift, the cost of benzine was 8-13 fr.; oil, 1-10 fr.; upkeep, 1-72 fr.; depreciation, 5-05 fr.; total, 16 fr. Wages of drivers, pointsmen, etc., 9-86 fr., bring the total cost per shift up to 25-86 fr. The number of ton-kilometres hauled per shift was 212, the cost per ton-kilometre being, therefore, 12-2 centimes. Average load, 16-3 tons; mean distance travelled, 26 kilometres. At the price mentioned above, the cost of petrol amounts to about 50 per cent, of the total, so that any alteration of x per cent, in the price of fuel would modify the total cost by x percent. Thus, with petrol at 28 fr. (47 per cent, below the average), the fuel cost per shift would be about 12-40 fr. Apart from the cost of petrol, the cost per ton kilometre depends on the wages bill and the weight hauled. Now the rate of wages is a matter over which the colliery owner has little control; and the higher this item, the greater the advantage of locomotive over horse haulage, because in the former case wages amount to only 38 per cent, of the total cost, as compared with a mean of 49 per cent, in the latter. The possibilities of economy appear to reside, as in the case of horse traction, in running long trains and high speed. Thus, in one case where the daily run per locomotive was originally 16| kilometres, and the trains were all made up of 32 tubs, a re-organisation of the traffic enabled the number of tubs to be increased as required, thus doing away with the loss of time pre- viously experienced at the terminal stations, and there- fore the engine mileage increased to 22-4 kilometres per shift, and the cost fell from 18-7 centimes to 13-3 centimes per ton-kilometre. In fact, during one month an average of 216 ton-kilometres was attained, at a cost of only 12-8 centimes per ton-kilometre, the total mileage being 24 kilometres per shift. 1 : 6-59. The mean tonnage per horse amounted to 4-7 tons, and that per locomotive to 16-3 tons, a ratio of 1 : 3-47. Total mileage per horse, 121 kilometres; per locomotive, 26 kilometres; ratio, 1 : 1-97. Ton-kilo- metres per horse, 32-14; per locomotive, 212. In one case the engines hauled trains 4| times as heavy as the horse trains, whilst in others the ratio was only 2j—a difference it is difficult to explain, seeing that the effort required varies directly with the weight to be hauled. The variations in the speed ratio (from 1-47 to 2-44) are also difficult to account for, since the reasons operating in favour of high speed (long roads, absence of compli- cated tracks, regularity of coal output, etc.) are the same in both methods of traction, and therefore the ratios should be fairly constant. In any case, the chief condition essential to the success of locomotive haulage, as compared with horse traction, is that the locomotive should be capable of hauling trains 4 to 4| times as heavy as horse trains, and make double the mileage per shift. Other expenses affecting the relative cost of the two forms of haulage are :—Cost of housing, upkeep of roads, upkeep of rolling stock, and wear on the rails. The first of these items is about the same in both cases, the cost of the engine sheds being about 6| times that of stabling, or in some cases less. The roads have to be kept in repair for the sake of ventilation just as much as for haulage, and it is difficult to apportion the share of each in the upkeep. Extra large' roads are not required for locomotive haulage, and in many cases no alteration is needed. Even if certain roads have to be widened, the increased size has no appreciable effect on the cost of upkeep; and, on the other hand, the benefits accruing to the ventilation will largely counterbalance the outlay incurred. Again, horses disturb the ballast on the permanent way, and make hollows between the sleepers, which have to be filled up at frequent intervals. The displaced ballast also chokes up the drainage gulleys, which have then to be cleared out. Since these two items disappear in the case of locomotive haulage, an economy is effected in this respect. Owing to the greater weight of the longer trains, the strain on the tub hooks and draw-bars is greater than with horse traction; but the chief source of wear on the