The Locomotive Of Today

The Boiler: Firebox, Firehole Joints. 17 boiler from lateral movement is by means of a cross plate bolted to the firebox, and fitting- between the frames of the engme, slotted holes allowing longitudinal movement for the ends on the retaining bolts. Jn m1anI °f the.earlier engines a support was provided for tne barre! of the boiler about midway of its length, either by carrymg up the motion plate high enough to form a saddle or by making a plate connection to the frames, but in modern engines such supports for the barrel are now commonlv omitted. 7 The internal firebox is, as already stated, usually made of copper m this country, the advantages of this metal being its unitormity and homogeneity of texture, freedom from lamina- tion and blister, and general trustworthiness when well selected, its great resistance to oxidisation and the corrosive action of various waters, the manner in which it resists tenacious adhesion of most kinds of scale, its great ductilitv and malleability which render it capable of being worked wit great ease, and its capability of bearing sudden and repeated racking strains. Further, it is an excellent conductor ot heat, and is well able to resist the wasting action of a erce, orced fire; the plates are about i-in. thick when new. The joint round the bottom of the box is made by means ot a ioundation ring of a width equal to the thickness of the water space, or to the distance left when the inner firebox plates are set out towards the outer shell at the bottom ; in either case rivets are passeel through the two plates and ring to form the joint. Ihe setting- of the plates requires to be very exact to suæ a good job, and the radius of the corners of the box should not be too sharp, or the difficulty of making tight joints is greatly inereased. The plates are attached to the ring; at the corners by putting rivets through at various angles, °r F Set bolts for the outer Plates, either of these methods being equally good if carefully executed. The ring- sh°u d not be cut out to take the lap of the plate, but the plate snould be drawn down at the bottom and the rinff tapered to. suit, as shown at A, Fig-. 4. Firehole joints are made in a variety of ways. We show pnneipal. At B, the back plates of the firebox and shell have holes cut through them of the required shape nc size, tnen a ring of the same thickness as these plates ar& apart is mserted between them, and the whole rivetted together by long rivets passing through the plates and ring- shows a modification of this : here the firebox plate is dished ut towards the shell, and a mueh thinner ring is rivetted in ; 2