The Abbeville press and banner. [volume] (Abbeville, S.C.) 1869-1924, 1893-01-11

ingenious thing of the kind ever made,
It has the superb record OF lifting a.:
,seveuty-ton boiler of the pier, towing
itself distance Of $50 feet, and lower
ing the boiler with delicate adjustment
into the armored cruiser New York I'M.
less than,twenty- five minutes. Only two
men were required to operate the MAJ
chine, and the ease with which tbei'
sesenty-ton bundle was Lifted from one
place to another suggested play rather
than mechanical engineering OF high I
grade. 4a y
-SAs the illustration shows, the derrick i
Is a big cone, IN the apex Of which is ]
set q huge mast, passing through the
arms of the machine, which stretch out;
from the top Of the cone. This cone is
simply series Of steel uprights resting
on d pontoon and enclosed with Q wood.
en- house. Inside the house are four \
engines Of forty horse power each con-
trolling the drum for the pulley cables
and the machinery for turning the arms
around and propelling the lifting pull
less towards the ends Of the main boom.
The height of the cone is sixty.dys feet.
It is strongly braced, and, on the
ground floor, is crowded with machin-,
ery. The mast is ffty-one feet high
above the boom. It is OF steel, aud hol-
low, being three feet in diameter and
braced here and there inside with extra
thicknesses of metal. It rest IN q socket
on ball bearings, forty-two steel balls,
each four inches 10 diameter and
absolutely true, being used in the rotary
motion Of the shaft and the long arms.
Another set of balls is used at the cap Of
the cone for lateral pressure as the arms
swing around. ssl S: II
From three stay plates that hook
themselves over the top Of the mast
strong guy gables stretch to the lifting
arm to prevent it from breaking.
The arm with which the lifting is
done is sixty-five feet long and the
other is fifty feet long. They arc
made of ''built.up' steel Of the
toughest quality. The longer ono
is fitted with travelling machinery,
so that it may deposit its burden at any
required distance within its scope away
from the mast. The short arm is an
chored to the foot of the cone by strong
cables, and when very heavy burden is
lifted two long steel arms are dropped
from the outer end to the SIDE of tho
pontoon below.
The long arm is fitted with two sets OF
pulleys, one for light lifts and one for
heavy lifts. The pulley apparatus ,s
called the 'sling," aud is fitted with u
inch wire ropes. There are ten coils on
the heavy hoist and two on the light.
The pulleys Of the heavy hoist are thirty
inches in diameter.
The pontoon on which tho derrick
rests Is of IRON and fitted with system
of water compartments. It is thirteen
feet deep, sixteen feet long, and sixty
two feet vide. When boiler or any
heavy weight is to be hoisted the water
is let in on the opposite side of the pom
toon so as to keep the derrick on an even
keel. As the burden glides toward the
outward end of the lifting arm more
water is admitted, and before any low
ering begins the machine is carefully ad-
iusted and made level. The derrick Is
fitted with pumping machinery so that
when its burden is left in place the
water is pumped out. In admitting the
water no pump is used. 1t is allowed to
run right in from the river.
The derrick is operated by the engi-
peer in the third story. He has a series
of levers like those in signal stations in
the block system of operating railroads.
At his back is steam gauge, showing
the condition of the boilers, and speak
ing tubes to communicate with his fire.
man at the engines beneath. There is a
large gong in the room, which is sounded
by the boss riggcr, who superintends
from the pier the wrapping of the cables
about the object to be hoisted and the
hooking of them to the pulley. The
signals tell the engineer when to stop,
90 ahead, lower or lift. BY means of
capstans on the pontoon the derrick can
tow itself about the shipyard. 1t ls
tool that saves an enormous amount of
time and energy.