IMPROVEMENTS IN HOPPER DREDGERS
Year: 1885

page_text: I, ANDREW BROWN, of London Works, Renfrew, in the county of Renfrew,
Engineer and Shipbuilder, do hereby declare the. nature of "my said Invention for
"IMPROVEMENTS IN HOPPER DREDGERS" to be as follows:-
My invention has for its object,
First, to construct the bottom of the hopper space with a maximum strength,
this is effected by placing one or more fore and aft girders in the wake of the
well sides.
Secondly, to construct the bucket ladder traversing carriage of maximum
strength to withstand the shock to which it is liable when dredging boulders, this
is effected by combining iron and steel plates and castings instead of the usual iron
castings, and also the use of a friction brake to sustain the said ladder traversing
carriage in position.
Thirdly, the combination of one or more propellers with shafting and gearing
attached to the ordinary bucket ladder for scouring out channels and bars by means
of the current caused by the action of the propellers assisted by the flow of the
river or natural current.
"
Fourthly, the construction of the deck in the wake of the open end of the well,
of maximum strength, this being effected by combining athwartship bulkheads and
upper deck plating.
Fifthly, the construction of the bucket backs with their links, connecting links
and picks, of steel or iron plates, instead of the ordinary cast steel backs and
forged links.
-
AMBROSE MYALL,
Agent for the Applicant.

page_text: Improvements in Hopper Dredgers.
I, ANDREW BROWN of London Works Renfrew in the county of Renfrew,
Engineer and shipbuilder do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:—
My invention has for its object,
First, to construct the bottom of the hopper space of maximum strength, this is
effected by placing one or more fore and aft girders in the wake of the well sides.
Secondly, to construct the bucket ladder traversing carriage of maximum
strength to withstand the shock to which it is liable when dredging boulders, this
is effected by combining iron and steel plates and castings in the construction of
the said carriage, instead of merely forming it of the usual iron castings, and also
the combination of a friction brake with the driving mechanism, to sustain the
said ladder traversing carriage in position.
Thirdly, the combination of one or more propellers with shafting and gearing
attached to the ordinary bucket. ladder, or otherwise suitably connected to the
dredger, for scouring out channels and bars by means of the current caused by the
action of the propellers assisted by the flow of the river or natural current.
Fourthly, the construction of the deck in the wake of the open end of the well
of maximum strength, this being effected by combining athwartship bulkheads
and upper deck plating.
Fifthly, the construction of the bucket backs, with their links, connecting links,
and picks of steel or iron plates instead of the ordinary cast steel backs and
forged links.
In order more clearly to explain the nature of my invention and the mode of
carrying out into practice the various parts thereof, I will now proceed to further
and more particularly describe the same by reference to the accompanying seven
sheets of drawings.
In Sheet I, Figure 1 is a cross section of a hopper dredger through the main
hopper. Figure 2 is a cross section through the side hoppers and bucket well, and
Figure 3 is a longitudinal sectional elevation through the lines X X in Figures 1
and 2, the said three figures being illustrative of the first part of my invention.
In the construction of hopper dredgers having a bucket well with hoppers on
each side of the well and a large main hopper at the end of the well extending
across the vessel, it has hitherto been customary to stop the longitudinal girders
which form the bottoms of the well sides, at the bulkhead at the end of the well,
and to provide one longitudinal girder in the centre of the main hopper with a pair
of doors on each side of it.
In order to remedy the weakness of this mode of construction, I, according to my
present invention, as shewn in the said figures 1, 2, and 3, Sheet I, provide two
longitudinal girders A A, which form the bottoms of the sides of the bucket well W
and the side hoppers C C in the usual way, but I extend these girders through
the bulk head E and across the bottom of the main hopper B. Three pairs of

page_text: doors D D D are provided in the main hopper and one pair D¹ in each side hopper.
This arrangement as will clearly be seen, gives continuous support and forms an
improved and much stronger construction of bottom and doors than those ordinarily.
used. The chains by means of which the doors D and D¹ are closed, are indicated
by dotted lines passing over pullies.
Although two continuous girders A A are shewn, I wish it to be understood that
I do not confine myself to such particular number.
The second part of my invention is illustrated in sheets 2 and 3.
In sheet 2, Figure 6 is a side elevation, Figure 7 an end elevation through the
lines Y Y on Figures 6 and 8, and Figure 8 a plan of my improved bucket ladder
traversing carriage.
The framing of the carriage F in place of merely being constructed of the usual
castings is formed as clearly shewn in the drawings of iron or steel plates, angle
irons and castings, rivetted, bolted or otherwise securely and suitably attached
together. Such construction gives maximum strength to the carriage and enables
it without liability to fracture, to withstands the shocks to which it is liable when
dredging boulders, or meeting other sudden obstacles. G is the upper tumbler and
shaft, and H the bucket ladder. The improved arrangement of friction brake and
driving apparatus is as follows. J is a long driving shaft supported in suitable
bearings and driven either by the main or auxiliary engines. The said shaft has.
keyways provided along its whole length, by which means it rotates the sliding
clutch K.
A lever L is keyed on the vertical shaft M, which said shaft is journalled in the
hollow standard M¹ and has a pinion on its lower end engaging with the toothed
segment N on the end of the horizontal lever N', the other end of the said lever is
provided with a fork N³, which embraces the clutch K, so that by moving the said
lever L the clutch may be moved either forward or aft on the shaft J.
When moved aft it engages with the end O2 of the sleeve which is affixed to or
forms part of the mitre wheel O, and by means of the mitre wheel O¹, spur pinion P,
and spur wheel P¹ drives the tumbler G.
When moved forward it engages with the end of the sleeve which forms part of,
or is affixed to the worm Q, and by means of the wormwheel Q¹ and pinions Q³ Q³,
which gear with the racks Q Q on the bed, traverses the carriage F with the
bucket ladder along the said bed.
A friction drum R is attached to the worm Q, and surrounded by a brake
strap R', which is worked by the handwheel R2. And by this means the carriage
may be firmly retained in any desired position on the bed.
A sliding stop S is worked up or down by means of a screw cut on the shaft of
the handwheel R. When the friction brake is screwed up to hold the traversing
carriage in position, the said sliding top is raised and abuts against the short tail
end of the lever L as shewn in Fig. 8, and so prevents the clutch being thrown into
gear with the worm Q, and when the clutch is in gear with the said worm, the tail
end of the lever being over the end of the stop S, prevents it being raised and so
prevents the friction brake being applied. Thus it is impossible to apply the brake
when the traversing motion is in gear, or to put the traversing motion in gear
when the brake is applied, and thus any liklihood of damage to the machinery from
these causes is avoided.
Sheet 3 shews a modification of the arrangement shewn in sheet 2 which said
modification allows the traversing motion to be put into gear when the buckets are
dredging, either by means of the main or auxiliary engines.
Figure 9 is a side elevation,
Figure 10 is a plan, and
Figure 11 a partial end elevation. Similar parts to those shewn in Figures 6, 7
and 8 are indicated by similar letters. F is the frame of the carriage and G the
upper tumbler shaft, J is the long driving shaft with key ways driving the sliding
n

page_text: When the clutch U is put into gear the said worm wheel drives the shaft T,
carrying pinions Q Q³, which engage with the racks QQ and so traverse the
carriage.
Keyed on the end of the sleeve, which is a continuation of the worm Q is a
mitre wheel O, which drives the mitre wheel 01.
1
The spur pinion P runs loose upon the shaft of the wheel O¹, but when the
clutch U is thrown into gear, the said pinion drives the spur wheel P¹ and so
actuates the upper tumbler shaft G and the buckets.
The clutches are thrown in or out of gear by means of levers V V¹, as shewn
clearly in Figure 11. A friction drum R is provided on the shaft T with brake
strap R¹ worked by handwheel R2 to hold the carriage firmly in position upon any
part of the bed when required.
It will clearly be seen that by this arrangement, the buckets may, when desired,
be driven at the same time that the carriage is being traversed along the bed. And
such motions may be obtained either from the main or auxiliary engines.
In Sheet 4 Figure 12 is a side sectional elevation, and
Figure 13 a plan partly in section, of a hopper dredger having two propellers
combined with the bucket ladder, to be used for scouring out channels and sand
bars by means of the current caused by the action of the said propellers assisted
by the flow of the current.
His the bucket ladder, shafts 22 are carried in bearings 3 on the side of the
said ladder, and have screw propellers 44 affixed to their ends. A vertical shaft 5
is driven by spur and bevel gearing from the main engines 13 as shewn, and a
horizontal shaft J is driven from the vertical shaft 5 by the bevel gears 6.
The shaft J corresponds with the shaft J shewn in Figures 6, 7, 8, 9, 10, and 11,
and has key ways provided along its whole length.
A bevel wheel 7, provided with feathers, slides along and is driven by the said
shaft J, and by means of the bevel gears 9, 9 and 10, 10 drives the shafts 2 2 and
propellers 44. The gears 99 and 10, 10 are carried in bearings on the ladder
traversing carriage but the said carriage and the gearing for driving the tumbler
shaft are omitted in the drawings to avoid complication. As will be seen from the
two dotted positions of the bucket ladder and propellers shewn in Figure 12, the
said propellers may be raised on deck, or be brought beyond the end of the vessel,
or be placed in any intermediate position required, or be gradually advanced by
the traversing mechanism while the dredger remains stationary.
The direction of the current caused by the propellers 4 is shewn by the arrows 11
while the natural current is indicated by the arrow 12.
Although two propellers are shewn, in combination with the bucket ladder,
I do not necessarily confine myself to this number, as I may combine therewith
more than two propellers, or only one if desired.
The dredger shewn in Figures 12 and 13 is provided with a main hopper B, side
hoppers C C and bucket well W, also the means of propulsion by twin screws at
each end, according to the specification accompanying my application for Letters
Patent No 7388 of 1885, (such twin screws being indicated by dotted lines) but it
will be understood that the application of that part of my invention relating to
the combination of a propeller or propellers with a bucket ladder, is not limited to
the particular form of dredger shewn.
Although the propellers 4 in Figures 12 and 13 are shewn as worked from the
main engines, they may, if required, be worked by or from an auxiliary engine.
And any suitable form of clutch may be employed to throw the screws 44 in or
out of gear with the engines.
In Sheet 5, Figure 14 is a side elevation and,
Figure 15 a plan of a dredger fitted with a modification of the third part of my
invention.
In this case two propellers 4 4' are employed, one on each side of the vessel.
. Their shafts 2 2¹ are carried in frames 14, 14 pivotted on the ends of the

page_text: The said shaft is rotated by the auxiliary engines 16, and drives the propeller
shafts 2, 2 by means of the bevel gears 161 16¹.
A framing 17, with ends overhanging the sides of the vessel, is provided-to
carry the ends of the frames 14, 14, with their propellers, by means of the chains
and blocks 18, 18, and winding drums 19, 19, are provided on the shaft 15 to raise
or lower the said frames 14, 14 and their propellers.
Suitable clutches may be provided to throw the winding drums 19, 19, or the
bevel gears 161, 16¹ in or out of gear as required.
Although the screws 4, 4¹ are shewn as worked by an auxiliary engine, they may
if desired be worked from the main engines 13 by any suitable connections. The
direction of the current caused by the action of the propellers is shewn by the
arrows 11, while the arrow 12 shews the natural current.
In Sheet 6, Figure 16 is a side elevation, and
Figure 17 is a plan of a dredger fitted with another modification of the third
part of my invention.
In this case, a propeller 4 fitted on a shaft 2, is carried by a frame 14 within a
well 20 in the centre of the vessel. The said propeller is represented as driven
from the main engines 13 in the following manner. A shaft 21 is driven by bevel
gears 22 from the crank shaft, and by means of pulleys and a belt 23, the shaft 21
drives a shaft 24, on which the end of the frame 14 is hinged or pivotted.
And the propeller is driven from the shaft 24 by means of the bevel gears 25.
The frame 14 is suspended from a frame 17 and is raised or lowered by means of
the chains and blocks 18, worked from the winding drum 19, as shewn. The
direction of the current caused by the propeller is shewn by the arrows 11 and the
natural current by the arrow 12.
Figure 4 Sheet 1 is a sectional longitudinal elevation, and Figure 5 Sheet 1, is a
plan of the open or well end of a hopper dredger illustrating the fourth part of my
invention.
· According to my improved construction, I connect the two parts of the vessel by
ath wartship bulkheads 26, in combination with upper deck plating 27 and the
plating of the well W.
This, for a sea going vessel, gives far greater security and strength than the
usual open end method of construction, while at the same time leaving ample
room for bringing the end of the bucket ladder forward of the end of the vessel.
The various views shewn on sheet 7 relate to the improvements in the bucket
backs, bucket links, connecting links, and picks, which form the fifth part of my
invention.
Figure 18 is a longitudinal sectional elevation, and Figure 19 is an end elevation
partly in section through the line X X in Figure 18, of an improved bucket formed
with the back and links of steel or iron plates, cut and bent into the required
shapes and rivetted or otherwise suitably affixed together, as clearly shewn;
instead of the usual construction of cast steel backs and forged links.
Figures 20 and 22 are longitudinal sectional elevations and Figures 21 and 23
are end elevations partly in section through the lines X X in Figures 20 and 22
respectively, of improved buckets constructed on the same principle as that shewa
in Figures 18 and 19, but somewhat modified in shape and detail.
Figure 24 is a longitudinal elevation and
Figure 25 is a longitudinal section of an intermediate or connecting link, also
made, as clearly shewn, of steel or iron plates formed into the required shape and
rivetted or otherwise securely affixed together.
Figures 26 and 27 are similar views of an intermediate link, made in a modified
form on the same principle.
Figure 28 is a longitudinal elevation and figure 29 is an end elevation, partly in
section on the line X X in Figure 28, of an improved pick for dredging chalk or
other stiff material, constructed of steel or iron plates, cut and bent into the
required shape and rivetted or otherwise securely affixed together, as clearly shewn.

page_text: It will clearly be seen that the construction of the various parts as shewn on
sheet 7, affords greatly increased strength with a reduction in weight, over the
ordinary method,
In conclusion, I wish it to be understood that although the said seven sheets of
drawings are given as illustrations of the mode of putting my invention into
practice, I do not necessarily confine myself to the precise details of construction
therein shewn, and described in this specification.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim, is-
(1) In a hopper dredger the improved construction of the bottom of the hopper
space by the use of one or more fore and aft girders, substantially as herein shewn
and described with reference to Figures 1, 2, and 3 Sheet 1, of the accompanying
drawings.
.
(2) In a hopper dredger, the method of constructing the bucket ladder
traversing carriage by a combination of iron or steel plates and castings, sub-
stantially as and for the purposes herein shewn and described with reference to
Figures 6, 7 and 8 Sheet 2 of the accompanying drawings.
(3) In a hopper dredger, the improved arrangement of the bucket ladder
traversing carriage in combination with a friction brake, substantially as and for
the purposes herein shewn and described, with reference to figures 6, 7 and 8
Sheet 2, and Figures 9, 10 and 11 Sheet 3, of the accompanying drawings.
(4) In a hopper dredger, the combination therewith of one or more propellers
with shafting and gearing, either attached to the ordinary bucket ladder, or
carried on separate frames, for scouring out channels and bars by means of the
current caused by the action of such propellers assisted by the flow of the river,
tide, or natural current, substantially as herein shewn and described, with reference
to figures 12 and 13, Sheet 4, Figures 14 and 15 Sheet 5, and Figures 16 and 17
Sheet 6, of the accompanying drawings.
(5) In a hopper dredger the improved method of construction for connecting
the open or well end, substantially as herein shewn and described with reference to
figures 4 and 5 Sheet 1 of the accompanying drawings.
(6) In a hopper dredger the improved method of constructing the bucket backs,
bucket links, connecting links and picks, substantially as herein shewn and
described with reference to Figures 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28 and 29
Sheet 7, of the accompanying drawings.