The sun., 1919-09-07


owing to turbine troubles.
THE second reason for the higher
economy at low power is the fact tina,
all auxiliaries In the engine room are
run electrically and 1t is well known
that in ordinary ships such auxiliaries
are great steam eaters. Thus from 20
to rs per cent. of the steam consump.
ton for all purposes in battle cruisers
and light cruisers Is accounted for BY
the auxiliaries. A large part Of the
gain In the New Mexico must there-
fore be attributed to the incident,
rather than to the direct causes.
There would be no difficulty in running
auxiliaries by electric motors In ships
fitted with mechanically geared tur-
bines, particularly as turbo- generating
sets have in any case to be provided
for lighting purposes.
There Is next the question Of
weight. II any saving effected in fuel
carried for a given radius OF action Is
counterbalanced by increased weight Of
tho installation itself there Is no gain
possible in substituting electric for
mechanical transmission for utilization
in increasing fghting elements In the
, design of q warship. The New Mexico
installation is said to weigh about 1880
tons and this works out at the equrn-
lent Of ITO pounds per s. II. p de-
veloped on the full power trial, where
as the machinery OF approximataIy
corresponding power in our warsnips
| works out at 140 pounds per s. H. P
This represents a difference OF abou.
400 tons against the New Mexico ma
chinery. 1t must be admitted, how
ever, that this Is the first batteslip
fitted with the system and there i
probability OF improvements in this
and other respects.
Electric Control for Machinery.
| The propelling machinery is cleo
trically controlled by switches which
can be placed in almost any part Of
the ship. The whole Of the maneuvrins
OF the machinery OF the electrically
propelled vessel can thus be effected
from any point of the ship that may
be desired. In fact, several manpu-
wiring stations may be installed, since
interlocking is easy. In this regard
the electric drive has no rival. The
value of the other claims made for II
is, however, disputed. Advocates Of
the electric drive point out that full
power is available for going astern,
instead Of only forty to fifty per cent
of full power which is available for
this purpose with gear drives.
In reply advocates of the latter as
sert that the limit to the power avail
able for going astern is fixed by the
danger OF caviation, which is likely to
give trouble in high speed vessels. II
on reversing from full speed ahead to
full speed astern the power trans
mitted suddenly is much in excess OF
DO per cent. OF the full power ahead
Since with the electric drive the tur-
bine operates under power station con-
ditions tits claimed that as high tenn
perature of superheat may be safely
adopted with this system at sea as Is
usual on shore. the consequent gain IN
steam economy would OF course Do
considerable. When reverse turbines
have to be fitted with gear drives there
Is a danger that the sudden admission
of superheated steam to the reverse
turbines. in changing from golhs
ahead TO going astern, or to the a4lea"
turbine when going forward again.
may cause dangerous distortions Oh
the turbine castings with consequem
blade stripping. There Is no douu'
weight in this contention, but the olnI'
oulties are not perhaps insurmouhF
able. The trouble with the New MeN.
leo on her westward voyage 10 saio W
have been due to blade stripping. ""
the other hand advocates OF mechnl..
eel gearing assert that at Jutlaha e,o.
trio gear OF every kind gave trouv,r
Under the shocks OF exploding sHe',,
and the like switches were thrown w.
ana circuits broken ali over iac ,;, SH,;,
while the mechanical and hydrauno
equipment proved satisfactory ~
again the difficulty Of mak'ns s"o.N
proof circuits is probably not insupt.
able. The high turbine efhc''neiI.s
claimed for the electric drive M eIu.s
ing speeds are discounted Tor ,"O
sons. In the frst place the aaV"''l -,
Is small when the most appFoNeu
rangement OF cruising turbines Is M ,sa
TO a gear driven ship; secona'y' "a
losses with electric TRANSMISSION
higher than with gears"