Fig. 2452.
In [Fig. 2452] is shown a method of making a steam-tight joint largely employed in England, upon the steam chest joint where the cylinders of crank shaft (inside cylinder) engines are bolted together. a is the flange of one cylinder, which is bolted to the other by the bolt b. c is a strip of copper let into a dovetail groove cut one half in one cylinder, and the other half in the other. After the bolts b are all firmly screwed home, hammer blows are delivered upon the top of the copper strip as denoted by the arrow e, expanding the copper so that it completely and closely fills the dovetail groove, and makes a steam-tight groove.
In riveting the copper it is necessary to hammer it evenly all along lightly, and only sufficiently to make it closely fill the groove, otherwise it will spring the joint open, and cause it to leak, notwithstanding the bolts b, which will give under the extreme strain.
Temporary joints are sometimes made by bending a piece of lead wire into a ring or frame, of such a size as to well clear the inside of the bolt holes. The ends are neatly joined, and the lead wire compressing and accommodating itself to the inequalities of the surfaces forms a joint.
Fig. 2453.