GROOVED TRAMWAY WIRES

Dominion, Volume 38, Issue 138, 8 March 1945, Page 9

GROOVED TRAMWAY WIRES

Eliminating Sparking

Till quite recently it was common to see showers of sparks given off from the overhead tram wires in Wellington when the trolly-head of a car passed a clip or a frog. This used to be most noticeable in the long tramway tunnel through Mt. Victoria. Last year the round wire was superseded by grooved wire in the tunnel, with the result that seldom, if ever, are sparks now seen there. Previously, the wheel of the trolly-head had to bump over suspension clips as it travelled along the wire, and the momentary disturbance from smooth running caused the wheel to jump slightly. _ . The new wire being used has two light grooves on opposite sides. These take the jaws of the clips, leaving the lower half of the wire for the trolly-head wheel to operate on smoothly—and without sparking. This is very important, as copper is not so easy to come by aS in years gone by. Indeed, a great deal 05 the overhead copper wire long in use on suburban lines is far too good to scrap. So, with the aid of an ingenious, little machine grooves are cut in the wire at clip points. Sparking means wear. Every time a spark is given off from overhead wires an infinitesimal amount of copper is used up or fused away. There is also a wearing effect on the trolly-head wheels.