The Mechanical Handling and Storing of Material

Ö24 THE MECHANICAL HANDLING OF MATERIAL 2. The impossibility of obtaining reliable statistics of a plant suitable for British requirements. 3. The large size of coal mined in England. 4. The class and size of coal wagons in use. 5. The restricted area available in most steam-shed yards. 6. The regular and adequate supply of coal between colliery and steam-shed. 7. The high cost of land for extensions and alterations to yards. 8. The impracticability of one plant capable of dealing economically with coal between (i) wagon and tender; (ii) wagon and stack; and (iii) stack and wagon or tender. 9. The varied local conditions existing at steam-sheds on any one line. 10. The large outlay necessary for installing a plant, and the cost of working various plants. 11. The breakage of coal. It is unnecessary to enlarge upon points Nos. 1 to 5, but as regards No. 6 it is found that, in those countries where long distances separate collieries from locomotive depots, it is absolutely necessary to keep large stocks of coal on hand, to carry over delays or stoppages; such stacks really represent a combination of current and stock coal. They are, so to speak, continually on the move, and the conditions render it essential to install mechanical means of readily taking up or putting down the coal, manual labour being out of the question from a commercial point of view. The economical and commercial points have been dealt with fully in Mr Cooke’s paper, and want of space forbids their mention here. With regard to breakage, it has been stated, on the authority of results of actual experiments in America, that “ each per cent, added to the slack means a reduction in earning capacity of the locomotive of about Id. per ton of coal fired, besides an average loss of unburned1 fuel itself of another |d. per ton for every 1 per cent, of slack.” This should emphasise the desirability of handling coal in such a manner that the minimum quantity of slack will be formed. The large amount of slack created by the present manual handling is perhaps not generally realised, and the following statement may come somewhat as a surprise. After a tender had been loaded in the ordinary manner, and the coal had been broken by the fireman to a suitable size, the proportion of slack left ranged from 13 per cent, in the case of Welsh coal, to 2’3 per cent, in the case of North Stafford- shire coal, although particular care had been taken to start the experiment with wagons from which all slack had been removed by hand. When to this is added the slack which is in the wagon when it arrives at the coal stage—in this case 10-2 per cent, in soft coal, and 2'9 per cent, in hard coal—the total is sufficient to make one pause to consider how this waste may be avoided. (In this test “slack” means all the small coal which was passed by a riddle with |-in. mesh.) Mechanical plants should therefore be designed with a view of dropping the coal as few times as possible between wagon and tender, minimising the height of fall, sliding the coal where possible, and delivering it in such a size that no additional breaking by the fireman is required. At the Crewe north steam-shed, at which about 130 engines are permanently stabled and about the same number are coaled daily, the quantity of coal transferred from truck to locomotive every twenty-four hours is about 450 tons, or 140,000 tons per annum. The plant, which is shown in Figs. 879 and 880, consists of a wagon tipper, an 1 This is the small coal which is lost through being drawn straight through the tubes as soon as it reaches the firebox, or which is blown off the tender.