as close to the machine as possible and the other
close to the foundation. This allows the taking down of all piping in
the passage completely and quickly without disturbing either threads or
lengths.

[Illustration: FIG. 7]

Studying the Blueprints

Fig. 8 shows an elevation and part-sectional view of a 1500-kilowatt
Curtis steam turbine. If one should go into the exhaust base of one of
these turbines, all that could be seen would be the under side of the
lower or fourth-stage wheel, with a few threaded holes for the
balancing plugs which are sometimes used. The internal arrangement is
clearly indicated by the illustration, Fig. 8. It will be noticed that
each of the four wheels has an upper and a lower row of buckets and that
there is a set of stationary buckets for each wheel between the two rows
of moving buckets. These stationary buckets are called intermediates,
and are counterparts of the moving buckets. Their sole office is to
redirect the steam which has passed through the upper buckets into the
lower ones at the proper angle.

[Illustration: FIG. 8. ELEVATION AND PART-SECTIONAL VIEW OF A
1500-KILOWATT CURTIS TURBINE]

The wheels are kept the proper distance apart by the length of hub, and
all are held together by the large nut on the shaft above the upper
wheel. Each wheel is in a separate chamber formed by the diaphragms
which rest on ledges on the inside of the wheel-case, their weight and
steam pressure on the upper side holding them firmly in place and making
a steam-tight joint where they rest. At the center, where the hubs pass
through them, there is provided a self-centering packing ring (Fig. 9),
which is free to move sidewise, but is prevented from turning, by
suitable lugs. This packing is a close running fit on the hubs of the
wheel and is provided with grooves (plainly shown in Fig. 9) which break
up and diminish the leakage of steam around each hub from one stage to
the next lower. Each diaphragm, with the exception of the top one,
carries the expanding nozzles for the wheel immediately below.

[Illustration: FIG. 9]

The expanding nozzles and moving buckets constantly increase in size and
number from the top toward the bottom. This is because the steam volume
increases progressively from the admission to the exhaust and the entire
expansion is carried out in the separate sets of nozzles, very much as
if it were one continuous nozzle; but with this difference, not all of
the energy is t