The Locomotive Of Today

The Framing, Wheels, etc. : Compensating Gear. 141 ends of the spring- are not provided with pins as in the last case, but the top plates are turned over to form solid pieces. which fit into sockets in the hangers, These latter have the top forged in one with the sides, which are carried clown on each side of an eye forming the top of the hanger bolt, and a pin passes through to make a hinge about which the spring may move when the load is appliecl. Nuts on the screws of the hanger bolts allow any necessary adjustment to be made. It will be seen from this that in effeet the weight of the engine is mainly carried at the pivots of the beams, and as the bogie carries its proportion of the weight at its centre, the engine is practically carried on three points, the most favour- able method for obtaining stability in running. In the case of engines with more than fbur wheels coupled it is not usual here, when equalisers are used, to provide all the wheels with them, but only two pairs, the remainder having independent springs. Sometimes, however, they are coupled across the engine by one transverse spring, with an end bear- ing upon each axle box. In America the whole of the wheels are invariably equalised, and in engines with many wheels this is often arranged for in groups; for instance, in “ Con- solidation ” engines, which have four pairs of wheels coupled and a leading “pony truck,” the truck and the leading coupled wheels are in one group and the remaining coupled wheels in another, coiled springs being often placed on the extreme hangers of each group, for the same reason that the rubber is. used in the type shown at K in addition to the laminated springs. The use of coiled springs is also common there, and at M is shown an example of equalising in which they alone are- employed. The beams themselves rests on the axle boxes,. and the springs are placed on the hangers, the pair being coupled together through the medium of bell cranks pivotted to brackets attached to the frames. Screws and nuts are pro- vided on the hangers for giving the required tension to the several springs. To obtain lateral flexibility in the wheel base various means are adopted. With coupled wheels which are neces- sarily rigid being all connected by rods, some are occasionally provided with blind tyres or reduced flanges, as has been already mentioned; but when the driving wheel base is not too long, as in four wheels coupled engines,, the remaining wheels are provided with one of several methods of allowing lateral play. Firstly by a four wheeled bogie or truck, secondly by a two wheeled bogie or pony truck, thirdly by radial or sliding axle boxes.