The Locomotive Of Today

The Framing, Wheels, etc. : Journals, etc. 135 wheel bears when forced home, the central portion being reduced to a less diameter ; no collar is formed at the end of the journal. In parallel axles, or in those which are larger in the centre than at the wheel seat and journal, a separate collar is often located at the inside of the journal and held by four set bolts as shown at J. On driving axles the eccentrics fulfil a similar function, and form the ends of the journal. If the size of the journals is to be increased for more bearing area it is best to increase the length rather than diameter, as speed is an important factor in friction, and this is added to if the diameter is increased. It is not good practice to place more than 8 to 9 tons as a maximum upon one bear- ing ; if more weight than this is to be carried bearings should be added at the other side of the wheel. In a few instances a bearing is provided in the centre of the axle. In some cases, especially with single leading or trailing wheels, outside bearings only are provided, as they are more accessible, and allow more room between the frames for the cylinders, fireboxes, etc. Owing to weaknesses of the road, etc., it is not always possible to put all the weight necessary for adhesion on one pair of driving wheels, consequently two or more pairs are connected together by means of coupling rods working upon crank pins projecting from the wheel bosses of inside framed eng’ines, or from outside cranks of those with outside frames. The holes for the reception of these pins are bored out after the wheels are fixed upon the axle, in a quartering machine provided with two heads having- boring- tools arranged at right angles to each other, with a sliding adjustment to suit different throws as required. The holes are bored out parallel, or with only a slight taper, and usually countersunk on the inner side. The crank pin is turned to tit with a projecting lip at the end, which can be hammered down into the counter- sink after the pin has been forced in with hydraulic pressure of about 45 tons. At K, a crank pin is shown with the part forced into the wheel boss on the left, then a collar against which the pin is pressed home and which also forms a distance piece to keep the coupling rod away from the wheel, next the journal, and lastly a smaller part on which a loose collar is fitted, secured by a taper screwed pin ; this holds the rod upon the crank pin. At L a larger section of a portion of the lip and boss is shown, the view on the left being that of the end of the crank pin as it appears when forced into position, that on the right showing it when the lip has been hammered into the counter-