re service simply consists of a
few coils and pipes, but of the first consideration in large
installations having numerous separate units supplied by oil and water
from an exterior source. The largest turbine units are often supplied
with water for cooling the bearings and other parts liable to attain
high temperature. Although the water used for cooling the bearings
indirectly supplements the action taking place in the separate oil
coolers, it is of necessity a separate auxiliary service in itself, and
the complexity of the system is thus added to. A carefully constructed
water service, however, is hardly likely to give trouble of a mechanical
nature. The more serious deficiencies usually arise from conditions
inherent to the design, and as such must be approached.

Special Turbine Features to be Inquired into

Before leaving the prime mover itself, and proceeding to the auxiliary
plant inspection, it may be well to instance a few special features
relating to the general conduct of a turbine, which it is the duty of a
tester to inquire into. There are certain specified qualifications which
a machine must hold when running under its commercial conditions, among
these being lack of vibration of both turbine and machinery driven, be
it generator or fan, the satisfactory running of auxiliary turbine parts
directly driven from the turbine spindle, minimum friction between the
driving mediums, such as worm-wheels, pumps, fans, etc., slight
irregularities of construction, often resulting in heated parts and
excessive friction and wear, and must therefore be detected and righted
before the final test. Furthermore, those features of design--and they
are not infrequent in many machines of recent development--which, in
practice, do not fulfil theoretical expectations, must be re-designed
upon lines of practical consistency. The experienced tester's opinion is
often at this point invaluable. To illustrate the foregoing, Figs. 66,
67, and 68 are given, representing, respectively, three distinct phases
in the evolution of a turbine part, namely, the coupling. Briefly, an
ordinary coupling connecting a driving and a driven shaft becomes
obstinate when the two separate spindles which it connects are not truly
alined. The desire of turbine manufacturers has consequently been to
design a flexible coupling, capable of accommodating a certain want of
alinement between the two spindles without in any way affecting the
smooth running of