472

MODERN STEAM PRACTICE.

is advisable to turn the shaft from end to end with a rough cut, toinsure a fair and true line, which tends to make the machinery run

more smoothly; but when theshafting is truly forged this isnot required.

Repairing couplings .—Thelying shafting is generallyfitted rough from the steamhammer. In the event of oneof these shafts breaking, aready means for temporarilyrepairing it is of the highestimportance. In the example (Fig. 350), the coupling is made infour pieces, bolted together lengthways with flanges, and trans-versely with bolts passing through discs cast on the coupling, thetorsional strain being taken on four keys.

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Fig. 350.—Repairing Coupling.

A, Coupling. B, Bolt holes. C C, Keys, n, Shaft.e, Recess for taking coupling on shaft.

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Fig. 351.—Repairing Coupling in Cast Steel or Wrought Iron .

Figs. 352, 353.—Repairing Couplings in Cast Iron .a, Screw shaft. b, Coupling. c C, Bolts. d, Set screws. e, Recessed nut. F, Keys.G G, Set screws. h, Raised strips.

VVe have arranged a simpler form of coupling, which possessesthe following advantages. It is evident that a shaft breaking atsea must be repaired as speedily as possible, and that the contactbetween the rough shaft and the coupling must only be partial,