The Locomotive Of Today

The Framing, Wheels, etc. : Coupling Rods, etc. 137 rods are also to ba seen, one of which will be near the wheels and the other on journals provided upon the pins, which in this case will project out a much greater distance, as the rods work in entirely different planes. In the case of outside cylindered engines the coupling rods necessarily have the same stroke as the connecting rods, as they are upon the same crank pins ; but in inside cylindered engines the coupling rods are placed opposite the cranks, and are allowed a reduced throw, usually one to two inches less than the cranks. At times they are both upon one side, and the outer cranks are then provided with an even less throw. A reason for placing them so is that the wear upon the axle boxes is reduced, as the pull upon the coupling rod is taken direct by the connecting rod, instead of being reversed through the axlebox. The wheels and axles are connected to the frames of the engine through the medium of springs, so that any shocks received by the wheels in running may be reduced and their effect lessened, and the liability of damage to the mechanism of the engine and to the road bed reduced ; further, the engine has not the tendency to mount the rails that it would have if the wheels and frames were rigidly fastened together. The springs are of various designs, those built up of long flat plates one upon the other being known as “ laminated,” whilst two of such springs placed one on top of the other, but with their curvatures reversed, are termed “ elliptical those coiled out of flat section Steel, with different diameters at top and bottom to accommodate the one coil inside the preceding one, “volute”; or of round bar or “Timmis” section, of equal diameter throughout, “ helical ” springs. Steel of the very best quality is invariably used for this purpose, and the completed springs are well tested in a scrag- ging machine before they are put under an engine to work. A common form of laminated spring is illustrated at A, Fig. 28, in elevation and plan. Thirteen plates, 5-in. wide by 1-in. thick, of varying lengths, are placed one on top of the other, the top one or master plate being the longest, and pro- vided with eyes at each end through which pins pass to couple the springs to the frames. Ihe plates are all held together at the centre by means of a buckle of wrought iron, which is shrunk on to them, with a long rivet passing through the plates and buckle and rivetted over at top and bottom. To keep the plates from moving sideways nibs and slots are pro- vided in all except the bottom one. Another-shape for the eye at the end of the master plate is sketched at B, and is used for underhung springs in which