. The Street railway journal . he steamcars from which the cement is unloaded. On the oppositeside is a depressed track for the electric cars which are to beloaded with the material. Fig. 2 shows the derrick used inhandling rail. The stock of rails is kept within range ofthe boom and car tracks run under it on two sides. A greatdeal of labor is saved by employing the derrick in loadingand unloading rails and other heavy materials. In use about the yards and in the city track constructionare several derrick cars of the type illustrated by Fig. mast is well braced and the crane is capable
. The Street railway journal . he steamcars from which the cement is unloaded. On the oppositeside is a depressed track for the electric cars which are to beloaded with the material. Fig. 2 shows the derrick used inhandling rail. The stock of rails is kept within range ofthe boom and car tracks run under it on two sides. A greatdeal of labor is saved by employing the derrick in loadingand unloading rails and other heavy materials. In use about the yards and in the city track constructionare several derrick cars of the type illustrated by Fig. mast is well braced and the crane is capable of liftingsix or eight tons. The crane motor is located near the centerof the car and the controller for it is in such a position thatthe motorman on the car can operate the crane. This type chief of which is that it is operated entirely by air. Theclutches, the throttles of the engines as well as their reversinggears, and the bucket dumping device are all controlled bymeans of air cylinders and .engineers valves. The main ob-. FIG. 5.—CONCRETE MIXER ject of this arrangement is to reducethe labor necessary to operate theshovel. Only one attendant is neces-sary, as the man usually required atthe crowding engine is dispensed engineers valves, which are ofthe type used in connection withstraight air-brake equipment on elec-tric cars, are mounted together nearthe base of the crane. The operationof these valves admits air to straightair-brake cylinders and the pistons ofthese cylinders open the throttles ofthe engines or operate the valve is used for hoisting theshovel, one for operating the crane,one for operating the brake of themain drum, and another for openingthe lid of the dipper. The governorof the main engine is also controlledby the valve operating the clutch onthe main drum in such a manner that
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectstreetr, bookyear1884
