An Improved Dredge.
Year: 1897

page_text: Date of Application, 15th Feb., 1897-Accepted, 11th Sept., 1897
COMPLETE SPECIFICATION.
An Improved Dredge.
I, GEORGE POLL, of 56 Oxford Chambers, Bourke Street, Melbourne, in the
Colony of Victoria, Miner, 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:-
The object of my invention is to provide a dredge for use in harbours, rivers
and the like for raising mud or other detritus or gold bearing deposits, which
dredge shall lift the material to be raised in a more economical and effective
manner than with dredges as at present constructed.
I carry the object of my invention into effect by making a hull somewhat
similar to those at present in use but I construct therein a well passing through
the hull. Above this well I erect a staging which supports guide rods extending
above and below the hull. Suitable guys steady and support the guide rods, and
the depth of the same may be varied to suit the depth at which it is required to
work. The guide rods are connected together at their ends and stiffened by cross
rods. The bucket having a covered and watertight top is secured to a vertical
and hollow shaft and revolves with the same within brackets provided with friction
wheels which are flanged to roll upon the aforesaid guide rods.
The bucket is made cylindrical in shape and has its bottom provided with
hinged flaps which may fall down to form a cutting edge and with a screw like
action may scoop up material into the bucket. When the bucket is loaded the
flaps are closed by means of a shaft which passes down to the bucket through the
hollow shaft before-mentioned. A crank handle is used at the top of this inner
shaft to revolve the same, and by means of a screw thread formed upon the lower
extremity the said shaft engages with a two-part nut attached to links which are
connected to the flaps. This said nut is of peculiar construction being made in
two halves which may be held to their work by a strap in order to actuate the
flaps, but when this strap is lowered the two halves of the nut separate or open
apart, under the action of suitable springs, and thus the nut being disengaged
from the shaft prevents the possibility of the bucket's rotation actuating the flaps.
The flaps being closed the bucket is raised by means of a chain passing to a
winch over a pulley attached to the staging, when the nut is liberated and the
material allowed to fall through the flaps at the bottom of the bucket into a chute
and over the side of the vessel into an ordinary punt.
The bucket is revolved by means of spur wheels and a vertical shaft connecting
with a spur wheel fixed upon the upper end of the hollow shaft.
It is well known to persons engaged in obtaining gold from river beds, that
considerable deposits of gold lie in the crevices of the rocky bed of the river, but
prior to this invention it has been practically impossible to recover such deposits.
By this dredge the mud may be cleared away from the river bed and workmen
may enter the bucket, be lowered to the bottom of the river, and scrape the
deposits of gold out of the crevices in the rocky bed.
In order that my invention may be most easily understood I will now proceed

page_text: to descrive the same in detail and shall for that purpose refer to the accompanying
drawings whereon,
Figure 1 is a side elevation of my dredge shewing the bucket lowered.
Figure 2 is a plan of the same.
Figure 3 is a vertical section of the bucket with its bracket.
Figure 4 is a vertical elevation of the same.
Figure 5 is a plan of the same..
Figure 6 is a side view of the spur gearing and bracket.
Figure 7 is a plan of the same.
Figure 8 is a side view of the nut and attachments.
Figure 9 is a plan of the same.
Figure 10 is a side view of the same.
Figure 11 is a side view of a square driving shaft and spur gearing.
Figure 12 is a view of a spliced shaft.
Similar letters refer to similar parts.
Referring to these views, a is the hull having a well a¹ and a staging a² which
supports the guide rods b. Ordinary railway rails are admirably suitable for
making these rods b. Guys 1 steady and support the guide rods above and below
the hull. The weight of the rods is taken upon chains 63 one of which is provided
on each side and being secured to the bottom of the rods pass over pulleys b³
which are secured to the staging a² and thence to the winch c by means of
pulleys When being raised by means of these pulleys and ropes the rods b
slide within brackets a and against friction rollers a Figure 5, fixed to the
staging. The bucket dis secured to shaft d' and revolves with the same within
brackets and 6 provided with friction wheels d³ which roll upon guide rods b.
The shape of the bucket is cylindrical but its bottom is formed as shewn in
Figures 1, 3 and 4 and is provided with hinged flaps which when let down and
revolving in the direction shewn by the arrow on Figure 5 cut into the material
to be lifted and raise it into the bucket. As the material rises upon the flaps it
is guided by guard plates do on to the fixed portion d' of the bottom of the bucket
and into the interior of the same. When the bucket is loaded the two halves of
the nut fare closed together in order that their threads engage the thread on
shaft such being done by lifting the strap ft and securing it by the eye bolt fo
over the lug f. The flaps may now be closed by turning the crank handle d
which will revolve the shaft f and draw up nut f¹ and links f which are connected
to the flaps, and shaped as shewn to permit free admission for large stones.
bucket may be kept down to its work by means of a rope which is attached to
bracket and passes around a pulley as to a winch c. The two part nut f' is of
special construction as may be seen by reference to Figures 8, 9 and 10 where it is
shewn on a large scale. The nut proper is made in two halves f¹ screw threaded
on the inside and having a wedge shape on the outside. The two part nut fits
freely within a framing or carrier 10 to which the links fa are coupled and
springs are secured to framing 10 and to each half of the nut and tend to
separate or disengage each half of the nut from the screw thread of the shaft f.
A strap f passes over the framing f10 and over the inclined back
faces of the nut and when forced up the wedge shaped or inclined
faces force the halves of the nut into position upon the shaft. The
strap is held in place by an eyebolt f which is hinged to the strap by pin f5.
Nuts forest upon a bracket f7 secured to frame 10 and a pin f8 prevents the eye
bolts from disengaging. As the various parts wear the nuts f6 may be
correspondingly adjusted.
The
Flaps d being closed the bucket is raised by means of wire rope or chain g
attached to bucket bracket d and passing over pulley g¹ to winch c. One of the
manholes a is then opened in order that the strap f' may be got at and be dropped
to liberate or open apart the two halves of the nut f1 and thus allow the flaps d
to fall and so the material will fall through chute h into an ordinary punt.
The bucket is revolved by means of a spur wheel ka pinion k¹ and a square

page_text: vertical shaft. The spur wheel k is secured to the upper end of hollow shaft a¹
and pinion is carried in a bracket built up upon jacket jo which carries the
upper end of hollow shaft d. The shaft is driven by any suitable motor, gearing
for example with spur wheel which being secured to the shaft near the deck
may revolve with a bracket k³, and pinion k may slide upon the shaft k² whilst
it is free to remove within its bracket k³ carried upon brackets j.
The upper end of the shaft passes through a bearing which revolves in
any suitable bracket bearing k bolted to the staging a³. It is obvious that I may
use a circular shaft in place of the square one and groove the same to engage with
a feather secured in the pinion k¹, also if so preferred a worm wheel may be used
in place of the spur wheel.
Shafts and may be spliced to suit the depth to be dredged and for this
purpose I provide couplings consisting of flanges secured to sections of the shaft d¹
and bolted together by bolts and a coupling 12 consisting of a sleeve into which
the ends of sections of shaft f enter and are secured by pins 73. When workmen
descend in bucket d one of the flaps d is closed and the other after being
uncoupled from its link is folded back and secured beneath such flap in any
ordinary manner. The workmen may then enter through one of manholes a
which are now closed. Air tube as is then connected to the bucket by union a
and air forced in by an air pump as 10. Or the hollow shaft d' may be increased
in diameter sufficiently to provide room for a man to descend into the bucket.
The covered-in side of the bucket is presented to the stream to protect the workmen
from its force whilst they obtain the gold from the crevices.
I wish it to be understood that I do not confine myself to the exact details
herein before set forth as these may be modified in several ways without departing
from the spirit of my invention.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:
1. A dredge constructed with a well through which guide rods may pass to
support a closed bucket, substantially as and for the purposes set forth herein.
2. A dredge constructed with a well through which guide rods may pass to
support a closed bucket revolved by gearing, substantially as and for the purposes
set forth herein.
3. A dredge constructed with a well through which guide rods may pass to support
a closed bucket revolved by a vertical shaft and spur wheels, substantially as and
for the purposes set forth herein.
4. A dredge bucket having a closed top provided with manholes, falling flaps,
and with a bottom formed as shewn on Figures 1, 3 and 4 substantially as and
for the purposes set forth herein.
5. A dredge bucket having a closed top provided with manholes, falling flaps,
and a screwed shaft and nut, substantially as and for the purposes set forth herein.
6. In combination a nut made in two halves, springs for separating the same,
and a strap acting upon wedge shaped faces, substantially as and for the purposes
set forth herein.
7. In combination, a nut made in two halves, springs for separating the same,
a strap acting upon wedge shaped faces and held in position by an adjustable
eye bolt and a pin, substantially as and for the purposes set forth herein.
8. A dredge constructed arranged and operating, substantially as and for the
purposes set forth herein and illustrated on the accompanying drawings.
1005