Publication: Electrical World
New York, NY, United States
A New Insulator Pin.
The accompanying illustration shows the type of insulator pin used on the overhead circuits of the Long Island Railroad Company. The pin, which is the invention of Mr. W. N. Smith, of Westinghouse, Church, Kerr & Co., who has applied for a patent on the device, will be placed on the market under the name of the "Smith-Grip Insulator Pin." More than 8,000 of these pins are used on the transmission lines of the Long Island Railroad, carrying 250-cir.-mil cables in spans averaging 150 ft. in length, and no failures have been reported after a year of service. A dozen or more standard sizes of an improved design of the pin are being worked up, to fit various sizes of cross arms and pole tops and to carry insulators of various sizes. While designed particularly for use with wooden cross arms, the pin can be readily adapted to steel cross arms or any special pin support; and also used in heavy catenary trolley construction.
The claims made for the pin are as follows: It does away with the necessity of boring holes in the cross arms, thereby conserving the whole strength of the arm and lengthening its life; the metal composing it is distributed in the most effective manner possible, and its cross-section is greatest next to the arm where the greatest resistance to bending is required; and finally the shrinkage of the arm can more effectively be taken care of by the U-bolt and strap than by any of the other forms of pin fastening in common use, as there is no tendency to distort the bolt, and consequently there is no possibility of the pin standing crooked upon the arm after the shrinkage has been taken up. Furthermore, it is practically indestructible, and instead of being one of the weakest factors in line construction it will be the strongest, as the cross arm/wilt not be weakened by holes.