M
E C H A N IZ A T IO N is but one of many ways in which the Hudson Coal Co., of Scran- ton, Pa ., has souglit to reduee the eost and thus offset the declining price of anthracite. Timber which re- ąuires freąuent renewal, and some- times is inadeąuate fo r the purpose, has been replaced by steel arches, but only where the expected life of the place to be kept open is seven years or more, fo r the cost of steel is 2i times that of wood, both fo r the arch itself and fo r its permanent lagging.Improved pipę couplings with rubber gaskets have been introduced i n compressed-air piping to give tighter and more flexible joints, longer life, and greater speed and ease in coupling. Many dumping in- stallations fo r reducing the disposal cost of the vast ąuantity of breaker refuse and mine rock have been de- vised and ereeted in the course of years, all showing marked eeonomies in operation. These have culminated in an installation which gives mini
mum expense and delay in the dis- position of materiał and, by its
applicability to great heights in dumping, is sparing in its inroads on valuable storage space.
Steel arches are used by the H ud
son Coal Co. to afford permanent support and always are made heavy enough to keep places open without renewal or readjustment. F o r these, no pressure-accommodating stilt sup- ports are provided, such as custom- a rily are used in European mines where greater depths afford pres- sures less readily controlled. These arches are construeted by shaping 4- or 5-in. I-beams (see F ig . 1.4) giving a elear span of 10 ft. and a radius of 5 ft. with a leg length of 2 ft. 6 in. A steel-arch set eonsists of two units, each embodying a 30-in.
leg with a ąuadrant. The ąuadrants of two units are connected at wlmt becomes the crown of the arch by a heavy steel splice, 18 in. long, held in position by four -f-in. steel bolts.
S p r a g s H o łd A r c h e s in P la ce
Arch members are drilled at the faetory with holes to accommodate six pipę sprags, or strats, held by
By R. D A W S O N H ALL
E n g ineering E d ito r , C oal A ge
f-in . screwed rods, by which tlie members are kept at the desired dis- tance from each other and preveuted from twisting, the latter a failing such sets have i f not loaded wholly within their piane and i f not secured to each other fo r greater stiffness.
A t eaeh sprag location, two holes have been drilled so that the sprags can be set either in a direct line or staggered at every set at 6-in. centers.
Distance between adjacent arch sets is maintained by f-in . rods act- ing as tension members and by standard pipes of 2$-in. exterior diameter cut to the reąuired length and serving as compression, or dis
tance, members. Before erecting the first arch set, all its sprag holes are fitted with these distance members or sprags. 'Where the sprags are in line and not staggered, in each hole to be used, a f-in . bolt, 2-1 in. long, is inserted, as shown in F ig . I B . Over the serew end of the bolt is slipped a special washer with an outer diameter of 2 in. and an inner
44 COAL AGE — Vol.43, No.9
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Sep łem b er, 1938 — C O A L A S E
diameter of 1 in. This washer, which is pushed baek until in tight contact with the web of the arch set, holds the screw of the bolt in place by its inner diameter and the pipę in place,
when fitted, by its outer diameter, because the interior of the pipę has a diameter of 2 Ar in.
Onto the free end of the bolt is screwed, until it reaches the washer,
a hexagonal buckie, 8 in. long and measuring in. across the flats. A tierod, which is of f in. diameter and 2 ft. 10 in. long and is threaded fo r 6 in. at each end, is screwed into the
A^1 ,-Tunnel //ner-.. and suflteient engagement with the buckie of that arch. W ith staggered
and each arch therewith construeted costs $11.S0. These costs cover splice plates and bolts and two eoats of norraally present or during freshets, they are shod with discarded circular superintendent in a written applica- tion accompanied by a print showing strengthened, replaced or supple- mented. In pumprooms and sim ilar found extensive applieation in sewer work, have been used (see F ig . 2 ). quently become battered, corroded
O ciagon al
tlie conneetion is not rigid and, as the sliding eontacts between coupling and line make the pipę line compres- sible and extensible, breakage from bending, compression, extension, water hammer and change of tem- perature need not be apprehended.
A fte r six months trial at speeified an excess of low-pressure ventilation at the working face can the tempta- tion. of miners to use compressed a ir for ventilation be curbed satisfac- torily, and such provision always is made.
C u t s H ig h D isp o sa l C u ł s Dumping, so easy a matter with coal, because the breaker conveyor or railroad loeomotive removes the materiał as it is dumped, is a costly a structural-steel ramp section con- neet the elevated rails with the main settlement, the correct gradient is maintained. A compressed-air cylinder sup
plied from a storage reservoir mounted below the dump body auto- matically causes the car to dump on the bank its rock load of about 25,000 lb. This reservoir is automatically recharged at the end of each return charged per shift. The installation was designed to handle 250 cars per