The Locomotive Of Today

The Engine : Motion Details, Valve Setting. 99 The motion details are generally made of wrought iron, and well case-hardened at all wearing points after being machined up to shape, they are then accurately fitted together by being ground up with emery powder and oil. The pinholes in the links, etc., are usually bushed, either with steel or gun- metal, for renewal when worn. The pins are prevented from turning in the holes and becoming loose by having holes through them and the rod ends, into which taper steel pins are fitted, and split at their small ends to prevent them from working loose and falling- out. Oil holes and grooves must be liberally provided as it may be difficult to get at some when the engine is moving-; care should be taken in practice to keep these clean. The setting of valves operated by link motions must next engage our attention, the mode of procedure may be as follows :—The eccentrics are set and fixed to the axle in the required position, as determined by the lap and lead, etc., and the straps fitted to them ; then, the engine being ready for the wheels and axles, these are run under and secured in their appointed position, the valve motion being next hung up in its place. Before coupling up the eccentric rods to the links, the valve spindles are marked to show the position of cut-off for each port; this can be done, if the valve cannot be seen as when the steam chest is between the cylinders, by holding a thin piece of tin in one port and carefully pushing the valve, which is in its buckle, up to it, then marking the valve spindle outside the steam chest with a trammel having two points at right angles to each other. The point at the end of the longer arm is placed in a centre punch mark or “pop” in the back of the steam chest or upon the motion plate, as may be found most convenient to the operator, and a line is then “scribed” by the point of the short arm on the valve spindle, and a small pop made. The tin is next taken out and placed in the other port upon the same cylinder, and the valve drawn back or pushed up to it, and the spindle again marked for that end; the same process is then gone through for the second cylinder. The eccentric rods are then coupled to the links, and the links to the valve spindles, and the engine squared or placed plumb,” then the driving wheels are slightly lifted off the rails, rested upon suitable rollers upon each end of a shaft reaching across the pit over which the engine stands, and which has a reversible ratchet upon it, so that the wheels may, by its means, be turned in either direction at will. The reversing lever is now placed in the position allowed by the particular builder to be that in which most of the