The Scranton tribune. [volume] (Scranton, Pa.) 1891-1910, 1894-09-15
SOMETHING ABOUT PRoPELLERs.
And the Different Casualties That Break
These Massive Castings.


The propeller of steamer is q COMPARE
lively insignificant object compared with
the huge body it propels against the COM
bined forces of wave and wind, but they
come to grief frequently in variety of
ways A few days ago the red D steamer
Venezuela, in calm sea, without breath
of wind almost, suddenly lost one blade of
her screw, just as suddenly and with as
little cause or notice as oyerripe fruit
drops from its parent bough.
Around the dry docks are numbers of
gigantic propellers, all in one stage or other
Of dilapidation. Some are cast in the solid
--thatis to say, the hub through which the
shaft passes and the fans which extend
from 1t are one solid casting. Others are
built or cast, rather, IN sections; the hub is
one, and each fan or blade is another,
which fit into bases made for them in the
hub, where they are screwed on by huge
bolts that ase set in the hub casting.
Where one fan or blade is broken it is
easily replaced as the makers retain the
models Of all wheels or propellers, as they
are indifferently called, which they cast.
Then the entire wheel is not rendered use
less, as in the case when a solidly cast pro
peller like the VeneGuela's comes to grief.
1t is extraordinary to see the proportion
of vessels that arrive having received some
damage to their propellers. Occasionally
damage is done by the shaft racing, as it is
technically called. That is caused by the
steamship pplunging head on into the trough
of a big sea, and 50 elevating the stern and
the propeller that it is completely out of
water, and being suddenly rid of the re-
sistance the engine runs away, so to speak,
just as an ordinary engine will do when
driving belt slips off or breaks. Occasion
ally propellers are broken by striking
floating logs or ice, and rarely by striking
whale or large fish, when it is so much
the worse for the fish.
But there is one curious fact always
noticeable about propellers that is, that
the extremities Of the blades are eaten
away as though by some corrosive acid.
They are pierced with holes of greater or
lesser depth, which weaken the points of
the fans so that they snap off. These
corrosions are said to be caused by the
action Of the water, but it seems strange
IudU InO wearing SnOulu Juke Ule form OF
honeycombing the metal instead of wear
ing it away smoothly, as the mere friction
of striking the water might be supposed
to do.
Recently screws or propelers are made
Of different combinations of brass and
other metals, especially for steam yachts,
and are very costly. A short time ago
Pierpont Morgan's yacht struck rock in
the sound. The force of the blow smashed
one blade clean off, although fastened on
by eight or ten 2-inch bolts secured by
massive nuts, and second blade was curled
up by the blow just like a sheet of lead.
This wheel was designed by Beaver Webb,
was only three bladed one and yet it
cost the comparatively enormous sum of
$500. 1t was made Of o composition
metal resembling brass in color, called
Mayanese bronze.
In large ocean steamships, if the pro-
pellers are not one solid casting it is usual
to cover the nuts and bolt points which
fasten Il fans to the hub with q cement.
This is so tenacious and becomes so hard
when once set that it rarely breaks until
its removal becomes necessary, when it
gives the workmen a hard tussle to re-
move it.-Brooklyn Eagle.