Round Top and Salem Bell trolley line insulator

THE "ROUND TOP" AND "SALEM BELL " TROLLEY

LINE INSULATOR.

WE illustrate this week two new forms of trolley line insulators, now being manufactured by the Johns-Pratt Company, of Hartford, of which the H. W. Johns Manufacturing Company, of New York, are the selling agents. Fig. 1 represents the "Round Top" insulator, specially designed for the most substantial work. It consists of a metal shell throughout, with projecting lugs for the span wire. This outside shell is filled with moulded mica insulation, which surrounds the central metal nub, which carries a inch bolt. The edge of the skirt is turned down over the insulation, and the whole insulation is anchored in such a way that it cannot be damaged by the most severe handling, or by the accidental concussion of the trolley wheel, should it slip off the trolley wire. Fig. 2 represents the "Salem Bell" insulator also used for a straight trolley line insulator. This insulator is very similar to their regular line insulator, but as will be seen has one important improvement, in the nub or receptacle for the suspending bolt both top and bottom. This nub has been increased in length, and counterbored so that the screwed part does not take the whole of the side strain but is relieved by the bolt fitting snugly into the counterbore. It has been found that the weakest part of the bell insulators was at the point where the screw entered the metal nub, and experience has shown that this weakness is entirely overcome by this change, and altogether prevents any danger of the threaded screw from breaking. The top nub is counterbored 3/4 inch and the bottom one 5/8 inch, which makes the shape of the insulator a little longer than the old one, but not so great in diameter, the total weight being about 18 ounces.

Figs. 1 and 2. - the "Round Top" and "Salem Bell" Insulators.