My present invention relates to the transmission of electric energy and particularly to the insulation of high tension electric lines and it has for its object to provide an improved form of supporting insulator for the line wire having special provision facilitating the tying or anchoring of the line wire thereon.  To these and other ends the invention resides in certain improvements and combinations of parts all as will ba hereinafter more fully described, the novel features being pointed out in the claim at the end of the specification.

In the drawings:

Figure 1 is a side elevation of a pin-type high tension insulator constructed in accordance with and illustration one embodiment of my invention, the view being taken from a direction in alignment with that of the line wire and

Figure 2 is a side elevation of the same insulator taken at an angle of ninety degrees from the point of view of Figure 1.

Similar reference numerals throughout the several views indicate the same parts.

My invention is illustrated in the accompanying drawings applied to a high tension pin-type insulator of the sort usually composed of porcelain, the porcelain clay being partly molded and partly turned. It comprises a head 1, an upper skirt 2 and a lower skirt 3 on the underside of which latter, centrally arranged, is the threaded aperture (not shown) that receives the supporting pin The head 1 is centrally grooved at 4 on the top forming a seat or saddle for the line wire or conductor which rests therein as it stretches from tower to tower on which the insulator are placed.

The line wire merely rests in the saddle and it is customary to tie it in place by means of a tie wire. The tie wire is usually a very short length of wire used to fasten conductor to insulator and is usually wrapped once or twice around the insulator in such a manner that the two ends come opposite each other, 180 degrees apart. These ends are brought upward and twisted around the conductor in the form of a spiral to make it fast to the insulator. The top wire groove or saddle is preferably of a longitudinal curvature indicated in dotted lines in Figure 2 to approximate the sag of the line wire as it passes over it in stretching from tower to tower.

In the practice of my invention I improve the form of the "side wire" groove for the tie wire in its relation to the "top wire" groove for the line wire to the end that the tie wire may be more securely engaged with the insulator and brought up to the region of the line wire with greater facility.  The side wire groove is preferably just above the upper skirt 2 and is indicated in the present

instance at 9. It extends around the insulator between the skirt and a flange or shoulder 5 formed on the head 1 below the line wire saddle 4 and intersected by the curvature thereof. It is my object to so form or shape the side wire groove that when the tie wire is in its proper position and holding the electrical conductor fast to the insulator, the upper limiting line of wire groove will be such in direction that it will closely follow ill its contour the natural curvature of the tie wire as it rises from the lower side groove gradually up to the conductor which lies in the top groove. This curvature is upwardly from the geometrical center of the insulator at the sides of the top wire groove 4 as indicated at 6 and is applied to the under side of the flange or shoulder 5, the low point being at 7 at the side of the line wire and the high point being at 8 just below the line wire or in alignment therewith. Therefore, as the tie wire is wrapped around the groove 9 and brought up to engagement with the line wire in the groove 4 there is no abrupt change of direction or the tie wire permitting a tighter wrapping thereof in its own groove and a more extended contact therewith as it rises to the region of the line wire. Furthermore, the difference in levels between the top wire groove and the porcelain shed or upper skirt 2 gives increased room for the linemen to twist the ends of the tie wire about the conductor or line wire in the usual manner.

Aside from the above advantages the general appearance of the insulator is greatly improved and its ultimate mechanical strength is increased on account of the ability to secure a lower side grip of the tie wire on the insulator with a corresponding decrease in the leverage placed upon the supporting insulator pin.

The method of forming such a side groove, variable in width is entirely practicable from a manufacturing standpoint by revolving the unfired porcelain in the usual manner on a potter's wheel against a cutting device having a gaited motion.

I claim as my invention:

A turned insulator having a circular head and a circular skirt below the same of much greater diameter, the head being provided on its top with a transverse line wire groove in the vertical axis of the insulator and being further provided with an encircling circular flange forming a side wire groove between itself and the skirt, said flange being upwardly curved from points at the sides of the line wire groove to a point in alignment with the latter and intersecting the plane thereof.

WILLIAM S. COOK.