1 Stage hoisting is applicable to any depth.
In hoisting from great depths the weight of the rope, which may exceed that of the cage and FIG.
In deep shafts hoisting speeds of 3000 or 3500 ft.
A mine should always be opened by drift or entry if practicable, as thereby the expense of hoisting and pumping is avoided.
Tanks operated by the main hoisting engines, and of capacities up to 50o gallons or more, are applicable under several conditions: (1) When the shaft is deep, the quantity of water insufficient to keep a pump in regular operation, and the hoisting engine not constantly employed in raising mineral, the tank is worked at intervals, being attached temporarily to the hoisting rope in place of the cage.
Hoisting engines are provided with powerful brakes and frequently with reversing gear.
The possibility of hoisting and pumping from great depths has been discussed, and it remains now to consider the other conditions which will tend to limit mining operations in depth - namely, increase of temperature and increase of rock pressure.
The hoisting speed is therefore slower, and as less engine power is required for a given load the cylinders.
and lowering them with the hoisting engines.
of the drum depend on the hoisting speed desired and the depth of shaft or length of rope to be wound.
Hoisting ropes are weakened by deterioration and breakage of the wires, due to corrosion and repeated bending.
According to a revised mining law of 1899 (subsequently amended), all mines are required to be in charge of certified mine managers, mine examiners, and hoisting engineers, when the services of the engineers are necessary; and every mine must have an escapement shaft distinct from the hoisting shaft.
Hoisting the lightweight bike to his shoulders, he walked to the paved Main Street before mounting.
running wheels which enable the end carriages to travel on the longitudinal gantry girders or runway, and the crab or jenny, which carries the hoisting mechanism, and moves across the span on FIG.
striking the shafts of the Comstock Lode, securing ventilation and cool air for the miners, draining the mines above its level, and obviating much pumping and hoisting.'
The latter includes not only the actual excavation of the mineral, but also haulage and hoisting by which it is brought to the surface, timbering and other means of supporting the excavations, and the drainage and ventilation of mines.
Vertical shafts are better adapted to rapid hoisting, and have therefore somewhat greater capacity, than inclined shafts.
The excavated material is brought to the hoisting shaft, or sometimes directly to the surface, in small mine cars, moved by men or by animals, or by locomotives or wire-rope haulage.
The size, shape and design of the cars depend on the size of the mine passage and of the hoisting compartments of the shafts; on whether the cars are to be trammed by hand or hauled in trains; whether they are loaded by shovel or by gravity from a chute; and whether they are to be hoisted to the surface or used only for underground transport.
This is similar to shaft hoisting, except that the grades are often quite flat.
The maximum load on the engine is thus greater and more power is required than for fixed drums. Steam consumption is economized, whenever possible, by throwing in the clutches of both drums and hoisting in balance.
The variations in engine load are thus reduced, and incidentally hoisting time is saved.
Self-acting tanks are occasionally built underneath the platforms of hoisting cages.
The special difficulties which attend deep mining, in addition to the problems of hoisting ore and raising water from great depths, are the increase of temperature of the rocks and the pressure of the overlying strata.
Near the top and bottom of hoisting shafts the tracks are usually graded to permit the cars to be run to and from the shaft by gravity.
When the mine is worked through shafts, hoisting plant must be installed for raising the ore and handling men and supplies.
This is important in mine hoisting,.
The engines used for winding or hoisting in collieries are usually direct-acting with a pair of horizontal cylinders coupled directly to the drum shaft.
In 1797 he brought reinforcements from the Rhine to Bonaparte's army in Italy, distinguishing himself greatly at the passage of the Tagliamento, and in 1798 was sent as ambassador to Vienna, but was compelled to quit his post owing to the disturbances caused by his hoisting the tricolor over the embassy.
The child-labour law of 1909 forbids the employment of children under eighteen years of age in blast furnaces, tanneries, quarries, in managing elevator lifts or hoisting machines, in oiling dangerous machinery while in motion, at switch tending, as brakesmen, firemen, engineers, motormen and in other positions of similar character.
He arranged with Marchand to leave the political question to be settled by diplomacy, and contented himself with hoisting the British and Egyptian flags to the south of the French flag, and leaving a gunboat and a Sudanese battalion to guard them.
In 1917, speed of transport of material becoming extremely urgent, it was decided to establish a train-ferry service; it came into operation at the end of that year, and the hoisting of cargoes by cranes into barges was largely superseded.
Herrmann, The Mechanics of Hoisting Machinery; F.
Working along side firefighters from Blue watch at Buxton, the team facilitated a hoisting system using technical rope skills to evacuate the casualty.
The latter consists of a framework carrying the hoisting barrel, with its driving motor and gearing, and a travelling motor, which is geared to the running wheels in such a manner as to be able to propel the whole machine; FIG.
For hoisting in deep shafts, and to reduce the weight of rope, tempered-steel wire of very high tensile strength (up to 250,000 or 275,000 lb ultimate strength per sq.
Hoisting ropes are weakened by deterioration and breakage of the wires, due to corrosion and repeated bending, and should be kept under careful inspection.
carrying the grooved sheaves over 'which the hoisting ropes pass, is known as the head-gear (fig.
Mining laws have proved chiefly serviceable in securing the introduction of efficient ventilation, the use of safety-lamps, and of proper explosives, to lessen the danger from fire-damp and coal-dust in the coal-mines, the inspection of machinery for hoisting and haulage, and prevention of accidents due to imperfection in design or in working the machinery.
Yes, I know, perhaps I had too much sun out on the boat deck, spent too much time hoisting the jib, or perhaps been keelhauled one too many times, but this distinctive Sauvignon Blanc took me by a lovely surprise.
The two often go hand-in-hand, but look at the Olympic lifters hoisting weights that much larger, oiled-up bodybuilders can't even budge, and you'll see there are other factors in play as well.
After clamping on their skies and hoisting day-packs, they set out on the groomed path.
A little bell jingled in the empty office as Dean entered and an unshaven man in his sixties took his time sauntering out from behind a curtain, hoisting up his suspenders as he moved behind the desk.
The ceremony of hoisting a flag and taking possession of the country in the name of the government of the Netherlands was actually performed, but the description of the wildness of the country, and of the fabulous giants by which Tasman's sailors believed it to be inhabited, deterred the Dutch from occupying the island, and by the international principle of " non-user " it passed from their hands.
Before quitting the bay the ceremony was performed of hoisting the Union Jack, first on the south shore, and then near the north head, formal possession of the territory being thus taken for the British crown.
The principal motion in a crane is naturally the hoisting or lifting motion.
On a smaller scale hoisting is also necessary for sinking shafts and winzes and for various underground services.
- Plan of direct-acting hoisting engines, compound Corliss engines and conical drums. Wellman-Seaver-Morgan Co., Cleveland, Ohio, makers.
If, for a twocompartment shaft, a pair of drums (or a single wide drum) be keyed to the engine shaft, with the ropes wound in opposite directions, the hoisting is " in balance," that is, the cages and cars counterbalance each other, so that the engine has to raise only the useful load of mineral, plus the rope.
Hoisting buckets or kibbles are employed for small (From The Colliery Engineer, May 1897.) FIG.
Though it is small and simple in construction for light work, for heavy hoisting at high speeds massively framed towers, often 80 to ioo ft.
Nevertheless, in very deep and large mines the time consumed in handling the men may make serious inroads on the time available for hoisting ore.
At the end of a shift the ore-skip is lifted from the shaft track - the hoisting rope being uncoupled - and the man-car put in its place and attached to the rope.
(2) For raising large volumes of water from deep shafts pairs of tanks are operated in balance in special shaft compartments by their own hoisting engine.
The architectural Mexicans, Central Americans, and especially the Peruvians, had no derricks or other hoisting devices, but rolled great stones into place along prepared ways and up inclined planes of earth, which were afterwards removed.
Fixed drums are best for mines in which the hoisting is done chiefly from one level; independent drums when there are a number of different levels.
The word usage examples above have been gathered from various sources to reflect current and historial usage. They do not represent the opinions of YourDictionary.com.