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.
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.
Fig. 11
AUTOMATIC DUMPING CAGES
14. A dumping cage is a cage so constructed that at the proper place it can be automatically tipped sufficiently to dump the contents of a car that is on it and will then right itself for the down trip, thus avoiding the necessity of removing the car from the cage, and saving time at the head. The construction of the cage is such that the car is held firmly in place while dumping. The principle of the self-dumping cage is illustrated in [Fig. 11], the cage being shown in its highest and lowest positions. The cage is made in two parts a and b. The fixed frames b slide on the guides k and have attached to them the safety catches and hoisting gear. The movable part a is united to the frame b by the hinge c. The platform d, on which the car rests, is fastened to the movable part a by the support e and further secured by the braces f. At the top of a is attached the wheel g that runs along the rail h, keeping a in an upright position until it reaches the dumping place i. Here the rail h is bent as shown and the wheel g is made to follow it by means of the guide j. This throws the top of a over so as to incline the platform and dump the car that is on it. On lowering, the cage rights itself when g passes below the point i. The part b is kept in a vertical position by means of shoes that slide on the main guides k.