lever-handles at the pit. These catches are so arranged that they fall forward by their own weight ready to hold the cage, but if the cage should come up it would readily push them aside if the banksman omitted to withdraw them, though the cage could not descend unless they were withdrawn. As a rule the catches are underneath the bottom of the cage, and are made to catch against the end of it; but sometimes catches are placed on the bank, to catch on the sides of the cage under the top hoop. In some

cases catches are not used, the engineman adjusting the cage to the banklevel without their aid.

#

Unloading Cages. In order to facilitate the unloading of cages on the pit-bank and at the pit-bottom, one side of the landing is made a little higher than the other, and the rails of the cage are given a little slope, sayinch in the length of the cage. This facilitates the moving of the waggons, but this -inch slope is not so effective as 3 or 4 inches of slope. But it would not do to have the waggons standing at such an incline on the cage in the shaft, therefore the rails are sometimes made to lift up at one end, and a short iron prop is fastened on to the underside of the rail, which is forced up when the cage is lowered on to the props, so putting the rails on to an incline and causing the waggons to run off.

FIG 541.-Double landings.

Another contrivance has been made by Mr. Fisher, of Clifton Colliery, where the empty waggon on the pit-bank is lifted up by a small engine, and so caused to run on to the cage.

Roofing of Bank.-In England the machinery on the bank is, as a rule, only partially covered, though there is a tendency at the present date to protect all the workmen from the rain and snow. On the continent it is customary to cover over the pittop and pulley-frame with a substantial building, inside which are the pulley-wheels.

Water-winding.-It is often necessary to use windingengines for raising water. In order that they may do this effectually, there must be a properly constructed barrel or tank of plate iron; such a tank is shown Fig. 543. It is capable of holding, when filled within 6 inches of the top, over 300 gallons. In a large shaft the water-tank may be made much bigger. It is

no use having a large tank unless there are large valves by which it can be quickly filled and emptied. In the figure are shown two valves, which open as the tank goes into the water. Upon reaching the top, one of the valves is opened by a lever, B, which strikes against a bar, A, fixed to the pit-frame. Owing to the great size of the valve, the water rushes out with great speed, and the tank is nearly emptied in a few seconds. In a shaft not exceeding 500 yards deep, this tank can be dipped, raised, and

emptied in about 80 seconds. Thus if there are two such tanks, they will lift together between 400 and 500 gallons a minute. With larger tanks and with a sufficiently powerful winding-engine, 1000 gallons a minute can be wound. A rather ingenious device has been employed by Mr. Galloway, in his sinking at Llanbradach, to fill a water-barrel or tank without dipping it overhead. The tank is round and covered at the top, made of iron plate. At the bottom is a valve by which the water can enter, and by lifting which the tank can be emptied. When the tank has been

lowered by the winding-engine to the bottom of the shaft, it is connected by a tube and coupling-joints with an exhausted vacuum vessel in a chamber above the water; by this means the

water is sucked up into the tank. A small air-pump on the

surface keeps the vacuum vessel exhausted of air. The vessel is an old boiler.

GUIDE

436

CHAPTER XX

66 SAFETY-HOOKS" AND "SAFETY-CAGES."

In order to avoid the danger of winding a cage too high, various safety-hooks have been invented by which the cage is disengaged from the rope and suspended at the same time.

Ormerod's Safety-hook. - Figs. 544 and 544a show

Ormerod's safety-hook. In this case the winding-rope is attached to the link X, and the cage to the chains Y ; the iron collar F is fixed in a very strong timber bar just below the pulley-wheel; the winding-rope passes through the centre of this collar. The hook is shown in working order in (1). The upper part will pass through the collar F; but not the lower part, which consists of three plates held FIG. 5444.-Ormerod's safety-hook. together by a centre pin E, and

maintained in the position shown in (1) by a copper rivetinch thick, P. When an overwind takes place, the lower shoulders of the plates H H are pressed together, shearing the copper pin P. This causes the shoulders K K to project, so that they cannot fall back through the collar; at the same time the pin of the rope shackle A is brought opposite the slot in the outer plates, and so escapes, whilst the pin B of the lower shackle is brought opposite a slot in the outer plates, into which it falls, but cannot escape. In this way the plates are prevented from resuming their original position. For lowering down again, the rope shackle is attached to the shoulder R on the inner plate, by which it is lifted, the centre plate having a slot by which it can move over the centre pin E after removing the pin C. The hook can then be lowered down through the collar until the cage rests on the bank, when it can be readjusted.

King's Hook.-King's hook is shown in Fig. 545. This consists of four plates. The hook is shown in working order in

A

E

E

D

FIG. 545-King's patent detaching hook.

3 and 4. When an overwind takes place, the shoulders C C are forced in, and the opposite shoulders D D are forced out; at the same time the hooks on the two internal plates E E are forced back from over the pin of the rope shackle A, which is free to escape, but the shoulders D D, catching on the top of the plate F, prevent the hook from returning. The weight of the cage, being suspended from the pin L, keeps the shoulders forced out, and so prevents the cage going down.

Either one or the other of these inventions is in use at nearly