4io

MODERN STEAM PRACXICE.

brasses, and cap. This is a neat form of connection; whether thebrasses have a plain exterior or are cut out in the pattern, thebottom part is generally cored out to save weight and metal. Fortrunk engines of the single dass the brasses are placed in a pillowblock, cast along with the piston, and two bolts pass through thepiston for securing the cap. This arrangement is adopted for forkedconnecting rods; but for single connecting rod ends, both in single-trunk and double-trunk arrangements, the pillow block and brassesare dispensed with, and a crosshead of wrought iron is substituted,with bosses forged on the end, through which it is securely boltedto the trunk. In single-trunk engines raised bosses are cast on thepiston, and accurately faced for fitting against, the bolts passingthrough the piston, and having their heads covered with a platelet into the piston, which prevents the steam escaping through thetrunk into the atmosphere; while in the double-trunk engine thecrosshead is secured by bolts which pass through snugs cast alongwith the trunk, and do not require to be made steam-tight, as inthe preceding case. The snugs should be strengthened with a deepfeather, so as to take the thrust and pull which is transmitted onall connecting-rod attachments.

The most approved form of connecting rod between the cross-

Fig. 293.—Connecting-rod End for Cranked Shaft.a, End forged on the piston rod. b, Cap. cc, Bolts and nuts. d, Brasses.

head and cranked shaft is that with solid ends forged on, slottedout for the reception of the brasses, with caps of wrought ironsecured by two large bolts. The part for taking the brasses canbe bored out, the bedding forming a true circle; the ends and capare forged, turned, and finished entire, with holes bored for thereception of the bolts, which are so spaced that part of the brassesrequire to be scooped out, which prevents them turning round in