TELPHERAGE 



259 



truck off the line ; similar results followed the application of any 

 sudden pull. Moreover, trucks, with two rollers, on a rigid 

 frame, even with so great a wheel-base as 22 inches, require 

 curves of considerable radius if we are to avoid serious binding 

 at the flanges. Notwithstanding these difficulties, the trains at 

 AWston, with a little care, run well and lightly, but the trucks 

 which have gone to South America are on the plan adopted in 

 the model ; they run much more safely, and turn much sharper 

 curves. They have two peculiarities first, each wheel, 7 inches 

 diameter (Fig. 7), is pivoted on an axis, B, vertically over the 

 centre of the wheels, A ; this allows the truck to run with the 



FIG. 7. 



freedom of a bicycle round curves ; secondly, the weight carried 

 is hung on a swinging arm, D, pivoted to the frame at a point, P, 

 on a level with the line. The result is that any force applied in a 

 plane containing the line acts as if applied at the bine itself, 

 and will neither lift the wheels in front nor behind. In the 

 model, the coupling, as you see, is on one line attached to the top 

 of the swinging arm (L, Fig. 7), where the coupling rods are well 

 out of the way. In the other line, the coupling is below the 

 road. Ihe swinging arm relieves the locomotive from all jerk 

 at stopping or starting. The truck is completed by a small hook 

 or catch embracing the rod. In case of any accident causing 



