Evening star. [volume] (Washington, D.C.) 1854-1972, 1896-05-16
MAGNETS THAT LIFT TONS.
Growing Use Of ElectrO-Magnets and
Electric Cranes,


By means of the electric crane and the
electromagnetic which were introduced into
this country and recently exhibited before
the American Society of Mechanical Engi-
neers, it is claimed that three men can
now do in fifteen minutes the same amount
of work which formerly taxed the strength
of six men for ninety minutes. 1t is found
invaluable in working with pig iron, heavy
castings and immense boiler plates.
1t is believed by engineering experts that
these lifting magnets will soon replace the
present forms of the derrick and travelling
crane. Preparations are being made to in
uoduce this device in the great Carnegie
works at Pittsburg. and its practical work
ings are being very carefully watched by
at least half a dozen large manufacturers
throughout the country.
AT first sight, 1t appears odd that a small
coil of metal weighing only about forty
five pounds can, by that strange force
known as magnetic influence, aided by the
equally mysterious power of electricity,
Hit tons of iron with no apparent grip
upon the weight to be lifted. 1t has been
proven by experiment, however, that such
an electro-magnet can Eft seventy-two
times its own weight.
In England the electric crane and electro
magnet are in use in a number of places,
in particular at the Woolwich arsenal and
at the Sandycroft works. Those in use at
the Wooiwich arsenal were designed by an
officer in the British army, and greatly
simplify the work of lifting and moving
heavy shot and plates of iron and steel.
Particularly is the electromagnetic of value
in lifting heavy shot, as previous to their
use workingmen experienced no end of
trouble in getting sings securely around
the shot. 1t was a long and heavy task,
and required the labor of many men.
Now the electromagnetic is lowered by
the magnetic crane and simply laid on the
side of the shell TO be raised; the turning
Of Love of ha hn nf ha nrap
switches on the current, and the work is
done. Here the new apparatus enables
three men to do the work which formerly
required nine men.
The construction Of the crane and magnet
is peculiar, and its inventors claim that
there is less chance of break than when
the old-fashioned tackle was used. Indeed,
SO far as is known. no accidents with the
new method have thus far occurred.
The electric crane Looks very much like
an ordinary swinging crane. Ii is con-
structed Of the best steel, the frame being
comparatively light. but of a strength far
in excess of any strain which will ever be
put upon II. From the base of an upright
steel beam long steel arm projects, first
upward at an angle Of forty-five degrees;
then, with bend upward and outward. it
extends for a distance nearly twice the
| length Of the supporting beam. Two steel
| rods, reaching from the top of the beam to
| the crane, act as supports or holds. One is
| attached to the crane about third of the
way from the Dds6 anu just At lIe DeUu,
| while the other Is attached to the upper
end Of the crane.
The wire through which the electric cur
| rent is carried from the battery at the
base Of the crane to the magnet runs up
| along the upright beam and across the up
per support to the end of the crane, then
over a small wheel to the end of the chain
| to which is attached the lifting magnet.
| Duplicate wires are used to prevent any
possible accident in case the wire should
foul with anything or in any way be
| broken. The switchboard governing the
current Is placed at the base.
In lifting weight Of 5000 pounds a cur
rent Of from three to four amperes at
from 20 to 30 volts Is used. The magnets
vary in size and weight from COMPARE
| lively small ones weighing ~ pounds to
| those having q weight of 30 pounds, but
| the lifting power of the magnet Is not al
ways in proportion to its size.
The body or core of the magnet used in
| lifting steel shells circular pieces of
| metal is shaped like an inverted ~" and
closely bound with wire, the winding being
| protected by brass fanges and by a thick
| covering of brass The two ends Of the
| wire winding are led to duplicate termi-
| nails, where they are Joined to the two
wires from which they receive the current.
Through the center of the magnet run two
| bars, to which are attached the rings by
which the magnet is attached to the hook
at the end of the pulley on the lifting
| chain.