THE writer is freq uen tly called upon to repair the “reversers” of electric locomotives, and in order to do so it is necessary to remove screws which are so located as to be inaccessible to an ordinary screw driver. The screws are locked by denting the edges with a center punch so that they will not readily become unscrewed. Furthermore, they are so arranged that there is no way of securing a grip upon them with a small monkey wrench or a Stillson. Under these conditions, the writer found it necessary to make a special tool from a cotter pin about five or six inches long. The eye of the pin was flattened out, so as to receive the blade of a screw driver and the pin was bent to the shape shown in the illustration. In order to make the tool of further service, several notches were cut in the adjacent edges of the pin, so as to ft taps of diferent sizes. These notches were made with a fle, while the pin was split open for the purpose. A quarter-inch iron pipe was then ftted over the pin and holes were drilled in the pipe mating the notches in the pin. The result was a combination screw driver wrench and tap or reamer wrench. The drawing illustrates successive stages in the evolution of the tool.
This article was originally published with the title "Screw-driver Wrench and Tap Wrench" in Scientific American 105, 20, 433 (November 1911)