AERIAL TRAMWAYS FOR OUR QUARTZ MINES

Otago Witness, Issue 1440, 28 June 1879, Page 8

AERIAL TRAMWAYS FOR OUR QUARTZ MINES

A gentleman from the quartz-reefs at Macetown, who visited Mr Alves' self-acting and aerial trjunway at the Fernhill colliery, for the purpose of making himself acquainted with its adaptability for mining purposes in mountainous districts, writes :—

11 1 think the principle will prove of much advantage to quartz-mines in rough country, especially where there is sufficient gradient to make the affair self-acting ; while from a description of the appliances persons interested will be best able to form their own opinion of its merits.

" The tramway is 75 chains in length ; the rope, a steel one, is five-eighths of an inch in diameter, and supported on tressel* every five chains, excepting in one case, whore it crosses a deep gully : there the span is nine chains. The tressels are of very simple construction, being composed of 4 x 4 timber, diagonally braced, and surmounted by a cro3shead supporting the rope. The tressels are 20 feet in height, excepting where the steep gully intervenes, when they are 50 feet, bo as to allow of the ' sag.' The rope forms an endless band, passing round two grooved wheels at either end, the lower wheel being driven by a steam-engine ÜBing about three horse-power. Tbe trucks containing the coal carry a load of 2^cwt. each, 40 of whioh are .used in the line, placed at regular intervals opposite to each other. The speed of the rope is three miles per hour, but it is capable of being driven up to seven miles. It ia capable of carrying 80 trucks, but only 40 are now used. With the full complement of trucks, 30 tons of coal could be brought down in the space of an hour. The modus operandi is this :— The rope passes round the drums the same as ordinary belting, being kept in its place and tight on tbe drums by the 'sag' between tho tresaels ; while, as the drums are nine feet in diameter, there is no fear of the rope slipping. At the place of discharge (the railway line) is stationed the bteam- engine, where there is a sort of raised circular plat-

form, under which revolves the drum or grooved wheel. As the trucks arrive they paßa over flanged pulley-wheels, which catch two rollers attached to the 'grip,' and which slightly raisa them off the rope, when they are transferred to a circular shunting-bar revolving round the platform. At half the distance they are tipped into the railway trucks with considerable ease, being hung upon a swivel on the principle of a 'mine kibble.' They are then passed in by the attendant along the circular bar to the up going rope, and the grip being quickly fixed, they proceed on their way to the mine for another load. The grip or clip is a very ingenious contrivance, representing a split nut, and made to fit into the strands of the rope. The two little pulJeywheels which support the truck on the shunt or circular bar also support the truckon the rope, and relieve the Btraiu of the ' grip. The grip is further relieved by an ingenious contrivance called a break, which onsißts of two arms projecting at either pnd of the grip outside the little grooved pinion-wheels, and which, when the incline is a steep one, catches the rope, acting almost the same as a break to a coach, only that the heavier the load the tighter it holds. At eaca cros3 arm on the tressels the rope passes over an 18-inch grooved wheel, but where there is a sudden change of level two wheels are used, set on a revolving arm, so as to relieve the strain at tbe change of gradient by rendering it less sudden. The buckets are suspended from the rope by means of curved hanging rods, thus enabling them to pass the cross-heads on the tressels, the weight keeping the trucks the same as if they were suspended by a straight bar. The operations at the starting s'ation at the mine are the same as at the discharging one, only that the trucks ar« disengaged from the rope and placed upon trollies, when they are wheeled to the "face" by the miners and filled with coal, and sent back again to the tramway. The miners receive the empty trucks and deliver the full ones themselves , " Where there \s along run, say not less than a quarter of a mile, this system of tramways could be applied with much advantage at Macetown ; and even in cases where the grade might not be sufficient for the apparatus to be self-acting, it could be worked by the machinery at the crushing-mill or otherwise. The men required to work it would be three— two at the top, and one at the place of delivery. The tiessels could be 300 feet apart, and perhaps les* than 20 feet high, while the timber required in their construction would be about 200 superficial feet. I think theße tramways would be less costly than any others, eßpscially where the length was considerably as the greatest portion of the expense is at the terminal points. •'After seeing the tramway, I inspected the mine. The Company hold a lease of 320 acres, the coal probably underlying the whole. The seam ia 19 feet in thicknea?, and outcrops frpm thesurface. In one place they are— using a mining phrase — paddocking it out; otherwise the seam is entered by a tunnel. So far as the supply is concerned there is plenty for all Dunedin for many years to come ; but the question of consumption I have nothing to do with. The coal appears to be of very good quality in compari son with what I have seen up-country, but as in all seams of lignite, the quality varies, I imagine the Fernhill Company might use a little more judgmeßt in what they send to market. This matter reminds me of some of the managers of quarz-reefs, who oftentimes spoil a good crashing by not being careful in the selection of their stone."