Fig. 12, Installation of the Motor, Showing Gears and Switch Contact Spring
The reversing switch, which is to be mounted on the under side of the motor frame, is shown in [Figs. 13] and [14]. It is provided with a control lever which projects out from under the truck frame. A small movement of the lever will produce the necessary changes in the connections. The operation of the switch may be understood readily from the diagram shown in [Fig. 15]. The moving element of the switch carries two pieces of copper, E and F, which connect the four stationary pieces of copper, A, B, C, and D, when the lever attached to E and F is moved to either side of its central position. The pieces of copper which are moved—E and F—are shown outside of the stationary pieces in Fig. 15 for purposes of a diagram only, and are actually directly over the ring formed by the stationary pieces.
Fig. 13, Details of the Switch, Shaded Portions Being of Fiber Insulation
The operation of the switch is as follows: Assuming that the current enters at the terminal marked 1 and leaves at the terminal marked 2, then the direction of the current in the armature and series field will be as indicated in the diagrams. The direction of the current in the series-field winding is different in the two cases, which will result in opposite rotation of the armature.
The base of the switch is made of ¹⁄₁₆-in. fiber insulation; its dimensions are shown in [Fig. 13]. It is to be mounted on the two pieces projecting outward on the under side of the motor frame, as shown in [Fig. 14]. Drill a small hole in each of these projections, as indicated by the letters H₁ and H₂, and tap them to take a small machine screw. Next drill two holes, H₁ and H₂, Fig. 13, in the piece of insulation, with centers the same distance apart as those drilled in the projections. One end of this piece of insulation is extended to form a mounting for a thin brass spring, the ends of which bear on the brass collars insulated from the axles, as shown in [Figs. 12] and [13]. The form of this spring and the method of mounting it are also shown in Fig. 13.
The sections which come into contact in the switch are made as follows: Mount four pieces of thin copper or brass on the fiber base with rivets having their heads countersunk. Cut a disk, 1 in. in diameter, from a piece of sheet insulation and drill a hole H, in the center of it. Also drill a similar hole H₃ in the center of the switch base. Mount two pieces of copper or brass, E and F, on the under side of this disk. The edges and ends of all six pieces of metal should be rounded off so that the pieces E and F will move freely over those on the base. The disk, or upper part of the switch, may be attached to the base by means of a small bolt placed through the holes at the center. A small spiral spring should be placed between the disk and the lower end of this bolt so as to keep the pieces of metal on the disk in contact with those on the base. Attach a small handle to the disk so that it will extend out on one side of the truck. Fix the switch into place by bolts through the holes H₁ and H₂, [Fig. 14], on the bottom of the motor frame. The electrical connections should be made as shown in [Fig. 15].
The detail of the couplers is shown in [Fig. 11]. They are made of brass, fitted to the upper crosspieces and fixed to them by machine screws. “Cowcatchers” may be made for the ends of the locomotive. Sheet metal, corrugated appropriately and bent to the proper shape, will afford the easiest method of making them. Those shown in [Figs. 1 and 2] are made of strips soldered together, and also to the upper crosspieces; they are strengthened by a cross strip at the bottom, opposite the point.
Fig. 14, View of the Under Side of the Motor, Showing How Switch is Fixed into Place