IMPROVEMENTS IN DREDGERS
Year: 1874

page_text: LETTERS PATENT to Andrew Brown, of the Firm of William Simons
and Company, of the Town and County of Renfrew, North Britain,
Engineers and Shipbuilders, for the Invention of "IMPROVEMENTS IN
DREDGERS."
Sealed the 16th June 1874, and dated the 24th January 1874.
PROVISIONAL SPECIFICATION left by the said Andrew Brown at the
Office of the Commissioners of Patents, with his Petition, on the
24th January 1874.
I, ANDREW BROWN, of the Firm of William Simons and Company, of
the Town and County of Renfrew, North Britain, Engineers and Ship-
builders, do hereby declare the nature of the said Invention of “Iм-
PROVEMENTS IN DREDGERS," to be as follows, that is to say :-
This Invention which relates to improvements in hopper dredgers has
for its object, firstly, to diminish the resistance to propulsion due to the
well and water contained therein. This is effected by providing the
bottom of the well with moveable doors which can be opened to allow of
the passage therethrough of the bucket ladder when dredging operations

page_text: are being carried on, and which are or can be closed after the bucket
ladder has been raised and when the dredger has to be navigated.
The object of the Invention in. the second place is to facilitate the
propulsion and steering of hopper dredgers. This is effected by providing
the hull with propelling and steering apparatus at each end, thereby
avoiding the necessity of turning the dredger round when it is required
to alter its course.
The object of the Invention in the third place is to improve the
raising and lowering of the bucket ladder, and it essentially consists in
the application or employment of hydraulic power for that purpose.
This is effected either by the direct attachment of the bucket ladder to
one or more hydraulic rams or by means of a chain coupled to an
hydraulic ram and passed round multiplying pulleys. The pressure
necessary for operating the hydraulic ram or rams is preferably attained
from an accumulator operated by an engine on board the dredger.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Andrew Brown in the Great Seal Patent Office on
the 22nd July 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ANDREW
BROWN, of the Firm of William Simons and Company, of the Town and
County of Renfrew, North Britain, Engineers and Shipbuilders, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fourth day of January, in
the year of our Lord One thousand eight hundred and seventy-four, in
the 37th year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Andrew Brown, Her special license
that I, the said Andrew Brown, my executors, administrators, and
assigns, or such others as I, the said Andrew Brown, my executors,
administrators, or assigns, should at any time agree with, and no
others from time to time and at all times thereafter during the term
therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the

page_text: the bottom of the well A when dredging operations are being carried on.
One end of each of the chains F is attached to a door B, from whence
the chain is passed under a guide pulley G, the other end thereof being
fixed to a windlass or drum H, whercon the chain is wound when it is
desired to raise the door. In place of hinging the doors B at one side,
as herein-before described, they may be hinged at both sides, in which
case they are divided at the middle.
When the dredging operations at one situation have been completed,
or at other times when it is desired to navigate the hopper dredger from
one place to another, the bucket ladder is raised, that is to say, the
lower end thereof is brought within the well, as shewn in dotted lines at
I, Figure 4 of the Drawings, and the doors B are lowered or closed (so
as to practically disconnect the outside water from the well A) by
unwinding the chains F from the drums H. The doors B are retained
at their shut position by lowering posts or beams J down one side of the
well A on to their upper sides, as shewn; the posts or beams J may be
raised and lowered by hand, or by means of chains, racks, and pinions,
or by other suitable raising and lowering apparatus operated by hand,
or steam, or other power, and they may have sufficient weight of them-
selves to keep the doors B shut, or that object may be effected by passing
bolts or pins through the posts or beams and the sides of the spaces
within which they are situated, or by other suitable locking arrange-
ment. Any desired number of doors may be provided throughout the
length of the well A, and these are or may be opened and closed simul-
taneously by placing the winding drums for the separate doors on one
shaft or by employing one winding drum for all the doors. The winding
drum or drums may be actuated by hand, steam,
or other
When
the doors are all shut the water contained in the well A may be pumped
out or otherwise discharged.
power.
In place of arranging the doors B precisely as shewn at Figure 1 they
may be placed flush with the bottom of the hull.
The object of my said Invention in the second place is to facilitate the
propulsion and steering of hopper dredgers (whether having one or more
bucket ladders and wells), and this is effected by providing the hull with
propelling and steering apparatus at each end, as shewn in longitudinal
section at Figure 2 of the Drawings. Separate steering wheels A and B
are provided for the rudders or helms C, D, at each end of the hull E;

page_text: by being provided with two screws F the necessity of turning the hopper
dredger round when it is desired to alter its course is avoided.
Figure 4 of the appended Drawings is a part section of the hull of a
hopper dredger longitudinally through the bucket well and wherein the
improvement embraced under the third part of my said Invention is
shewn applied. This improvement consists in raising and lowering the
bucket ladder A by bydraulic power, for which purpose the lower end of
the bucket ladder is attached to the rod B of the piston or plunger of an
hydraulic cylinder C by means of a chain D, one end of which is secured
to the bucket ladder, and from thence the chain passes over a pulley E
carried in the upper part of the triangular shears F, thence under and
round the pulley G attached to the rod B, from whence it is conducted
to an eye or ring H fixed in the shears F, whereto the opposite end of
the chain is secured.
When it is desired to raise the bucket ladder A the lever or handle a
is operated so as to admit water under pressure into the cylinder C from
the pipe b, the piston or plunger is thereby forced downwards, and in
descending raises the lower end of the bucket ladder A into the position
shewn in dotted lines at I, Figure 4, by means of the chain D. The
bucket ladder is again lowered when required by allowing the water to
escape from the hydraulic cylinder C through the pipes c and d when
the weight of the ladder A draws the piston or plunger upwards until
the rod B.thereof is in the position shewn on the Drawings, or at some
other position corresponding to the desired depth of immersion of the
5 lower extremity of the ladder.
In place of arranging the hydraulic cylinder C as shewn at Figure 3
it may be situated horizontally or at any other suitable angle.
Under another arrangement (not shewn on the Drawings) the lower
end of the bucket ladder is attached directly to one or more hydraulic
rams, in which case the position of the hydraulic cylinder or cylinders
is or may be inverted, but the said cylinder or cylinders is or are pre-
ferably fixed upon trunnions so as to be capable of moving through an
arc as the bucket ladder is raised or lowered. The pressure of water
necessary for operating the hydraulic rams or pistons is preferably
haand th

page_text: Having now described and particularly ascertained the nature of my
said Invention and the system, mode, or manner in or under which the
same is or may be used or practically carried into effect, I would observe
in conclusion that what I consider to be novel and original, and there-
fore claim as the Invention secured to me by the herein-before in part
recited Letters Patent is,―
First. Providing the wells of hopper dredgers with doors at their
lower parts or bottoms whereby the resistance to propulsion of the
dredger is diminished, substantially as herein-before described and shewn
at Figure 1 of the appended Drawings.
Second. Constructing hopper dredgers (having either one or more
ladders and wells) with propelling and steering apparatus at each end of
the hull, substantially as shewn at Figure 2 of the Drawings hereunto
annexed.
Third. The employment of hydraulic apparatus for raising and lowering 1
the bucket ladder, substantially as herein-before described and in part
illustrated at Figure 4 of the accompanying Sheet of Drawings.
In witness whereof, I, the said Andrew Brown, have hereunto set
my hand and seal, this Sixteenth day of July, One thousand
eight hundred and seventy-four.
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