Page 179 - Steam Turbines Design, Applications, and Rerating

158 Chapter Nine

(a)

(b)

(c)
Figure 9.1 Principal coupling types used in major turbo-
machinery: (a) diaphragm coupling; (b) gear type coupling;
(c) solid coupling. (Asea Brown-Boveri, Baden, Switzer-
land)

The flanges of a rigid or solid coupling are normally forged on as
shown in Figs. 9.1c and 9.2, although they may occasionally be shrunk
and keyed on. They are connected together by means of bolts. The fric-
tion between the two coupling halves is sufficient to transmit the
entire torque. Only a flanged coupling can be used in the case of large
turbogenerator units due to large short-circuit torques.
Occasionally, an intermediate shaft, flexible enough to allow for mis-
alignment of the same order of magnitude as other types of couplings,
connects the two shaft ends of the machines to be coupled together.