. The Street railway journal . reason, as well as for cheapness and convenience, the methodshown in Fig. 3 was decided upon, though there are some simplermodifications of it still under experiment. The diagram, which isintended to illustrate the principle only, shows, in the first place,the cast-iron box which is laid in the street. This is surroundedby a gunmetal stud S, faced with a phosphor-bronze wearing cap. 58 STREET RAILWAY JOURNAL. Vol. XV., No. i. This stud is insulated from the iron box by a sheet of non-porous road material is placed around the stud to make upthe level. T
. The Street railway journal . reason, as well as for cheapness and convenience, the methodshown in Fig. 3 was decided upon, though there are some simplermodifications of it still under experiment. The diagram, which isintended to illustrate the principle only, shows, in the first place,the cast-iron box which is laid in the street. This is surroundedby a gunmetal stud S, faced with a phosphor-bronze wearing cap. 58 STREET RAILWAY JOURNAL. Vol. XV., No. i. This stud is insulated from the iron box by a sheet of non-porous road material is placed around the stud to make upthe level. The box is filled with oil, which besides performing the functionpresently to be considered, maintains very high insulationthroughout. The switch is attached to the stud and comes awaywith it in one piece. Being only about 4 ins. in diameter no diffi-culty is found in making a perfectly watertight joint. The next point to consider is the method of making electricalcontact. The requirements of switchpoints for disconnecting sur-. that event the fuse would be blown, effectually protecting the pub-lic from the possibility of a stud being left alive in the roadway. It will be seen from Fig. 3 that three cups are employed; thetwo outer being connected to the main and the stud main cup is inclosed in a metal sheath (not shown) perma-nently connected to earth, so that it is impossible for current toreach the stud except when the yoke is down. It will be seenfrom Fig. 3 that when the plunger is down it earths the centercup, so that if from any accident whatever the yoke piece fails toopen the switch alter a car has gone past, the plunger puts thestud to earth and blows the fuse between it and the main. Eithershunt or series coils may be used to connect up the switch practice a shunt coil is preferred because the slightly increasedexpense is more than compensated for by the smallness of thebulk. Only one skate is employed, and this is in the center of thecar. Th
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectstreetr, bookyear1884
