The Mechanical Handling and Storing of Material

CHAPTER XXXVI 'ig 832. Perspective View of Rigg’s Tipping Machines, COLLIERY TIPS OR TIPPLERS The coal tips described in the preceding chapter are mostly intended for the purpose of manipulating standard gauge railway trucks, but there is no reason why similar appliances should not be built on almost identical lines for the purpose of emptying colliery tubs. Appliances for this purpose are, probably on account of their smaller size, of very different construction. They are generally known as “tipplers, and are built in a variety of forms, in most cases extremely simple, and too well known to require detailed descriptions, those delivering backward always being preferable, as they cause less breakage than those delivering in a forward direction. A few types of more recent date are worthy of notice, and are here fully described. It will be seen that these coal tipplers are mostly of the type which discharge below the level of the rails. Of the many improvements introduced for the purpose of mini- mising breakage, the devices for tipping coal with the least pos- sible damage stand perhaps first, as the value of coal is in almost all cases dependent upon the size of the pieces received by the consumer. From its arrival in the tub or tram at the pit’s mouth each transfer has the effect of more or less diminishing its value. Though the more friable kinds of coal sustain some damage by abrasion, more or less inseparable from transit in railway trucks, the most serious injury is generally incurred in tipping at the pit and in loading on ship- board. At collieries many different devices have from time to time been adopted with a view to preventing breakage, but these devices necessarily vary with the charactér of the coal in different districts. Thus, in Monmouthshire and South Wales the iron trams are provided with hinged end doors or bars, which are removed on the forewheels falling into recesses at the head of the screen ; or else the necessary angle of delivery, about 35 , may be obtained by a tram being placed on an oscillating platform so arranged as to allow of its tipping to the required angle of clearance. The so-called “box-tubs”—that is, tubs having no doors—are also variously tipped in balanced and unbalanced frames either backwards, forwards, or sideways on to the screen, sometimes under the control of a brake. In cases where the coal is not heaped above the top of the tub, a horizontal door is sometimes shut down upon it, and not 589