The Locomotive Of Today

The Engine: Walschaert’s Gear, Morton’s Gear. 109 is directly operated by it, and therefore the radius rod must be at the bottom of the link when the engine is in iore gear ; if, however, the eccentric is fixed at the opposite side of the axle and leads when the crank is turning backwards, the bottom of the link will be the “back gear" position. The opposite end of the slot link, will, ot course, have a motion exactly the reverse, therefore, moving the radius rod up will cause the engine to run in the other gear. In the illustration the engine is shown in full “ fore gear.'’ The slotted link is shown of the open type, but the box link may be, and is, often used, the curvature of the slot being made equal to the length of the radius rod. In the arrangement illustrated the combination lever is cranked, or set, this being done to clear the leading axle, but the action of the lever is exactly the same as it would be if a straight one were employed between the given centres. It is less difficult to arrange the design of this motion for equal points of cut off at each end of the cylinder than it is with either the skifting or stationary link motions, owing to the very intimate relationship which exists between the piston and valve positions and movements through the combination lever. The general accuracy of the movements of the valve when actuated by this gear, is not liable to be deranged by wear, owing largely to the reducing effect of the combination lever, slack at the bottom of it being lessened very much at the top, and its effect almost nullitied. This motion is not largely used in Britain, but is very extensively employed on the Continent owing' to the ease with which it can be fitted to, and its suitability for, outside cylinder engines. ÅVhen used on these it is usual to employ a return crank fixed to the crank pin instead of an eccentric, and in many engines, where there is a difficulty in putting the reversing" shaft and its connections in the position shown, the radius rod is prolonged and carried beyond the quadrant link, for the reversing arm to be coupled to it. There are many locomotives fitted with a modification of this gear, in which the distance between the centre of driving axle and valve is too small to allow of an arrangement as shown ; in these, the quadrant link is hung up with its curva- tures reversed, and the radius rod laid between the link and driving axle, the valve rod being lengthened to suit, and connected as before by means of the combination lever to a projection below the crosshead; this arrangement gives equally good results as that shown. In Mortons gear the motion is taken from the connectmg rod and crosshead, no eccentrics being used. Ihe connecting-