TABLE I_Hoisting Appliances

==================+=========================+=========+========

Platform | Guides | |

-----------+------+--------+----------------+Safe Load| Weight

----+------+ Feet | Inches +------+---------+ |

----+------+------+--------+------+---------+---------+--------

4 | 3 | 6 | 6 × 6 | 4 | 6 | 5,000 | 2,000

6 | | 10 | 6 × 10 | 6 | 3 | 8,000 | 3,800

====+======+======+========+======+=========+=========+========

=11. The Heavy Steel Cage.=--The cage that is shown in Fig. 8 is made

of iron and steel except the wood flooring, which is laid in two

courses, one lengthwise and one diagonal. The joints should not be

driven too tightly, as the wood is likely to swell. The track is bolted

to the floor, or =deck=, of the cage. The cast-steel safety dogs are

operated by steel springs _a_, coiled about the bars _b_, which are

connected to the drawbar _c_ by chains, as shown. The drawbar drops if

the rope breaks and thus assists the action of the springs _a_. This

cage is in use at both coal and iron mines, and is built to suit any

size of shaft and guides. Standard sizes are given in Table I.

=12. The Light Steel Cage.=--Fig. 9 shows a light steel cage much used

at gold and silver mines. It has a spring drawbar and steel safety

dogs, operated by steel springs, as in Fig. 8, but the floor is of

steel grating in order to give as little air pressure as possible

against the cage. The openings _a_ in the side frames are provided so

that through them the nuts can be tightened on the bolts that hold the

shaft guides. The cage is provided with bails _b_ that swing down over

each end of a car to hold it on the cage.

[Illustration: FIG. 9]

=13. Multiple-Deck Cages.=--Cages are sometimes built that have two

or more decks or platforms one above the other, thus giving greater

hoisting capacity to a shaft. A two-deck, safety, hoisting cage is

shown in Fig. 10. The upper deck is heavier than in a single-deck

cage of similar construction. The lower deck is suspended from the

upper deck by means of pins so that it may be removed at any time. A

double-deck cage may be used by first changing the car on the upper

deck and then bringing the lower deck to the track level and changing

the other car. Time can be saved by having two track levels, both at

the loading and landing stations, enabling both decks to be loaded and

unloaded at the same time.

[Illustration: FIG. 10]

=Multiple-deck cages= have been mainly used at ore mines in America and

very few coal mines have been equipped with them. Cages are also built

to accommodate two cars placed either side by side or end to end.

[Illustration: FIG. 11]