IMPROVEMENTS IN DREDGING MACHINERY
Year: 1884

page_text: I, JAMES WELMAN of Poole in the County of Dorset Engineer do hereby declare
the nature of the said invention for IMPROVEMENTS IN DREDGING MACHINERY,"
to be as follows:-
My invention relates to improvements in that class of dredging machinery where
the material or spoil is raised by means of a current of water through a pipe or
pipes connected to a pump and having the lower ond or ends lowered into the river
estuary or sea so as to nearly touch the bed.
In some cases the bed of the river or sea to be dredged is a hard compact claylike
material or a conglomerate mass or having looser material only on the surface and
so prevents the raising of the material or spoil by the current of water up the pipe
described.
My invention provides a means of cutting through or breaking up the bed and
an agitation of the spoil so as to enable the current of water to raise it.
The means I adopt for effecting this are as follows :—
I enlarge the dredging pipe a short distance above the nozzle to any size that
may from the nature of the material to be dredged be found necessary in order to
divert the current. In this enlarged part of the pipe I place for example a screw
propeller having two or more blades or made in the form of a continuous screw or
a turbine.
I fix the propeller on a suitable spindle provided with bearings above the
propeller and with a bearing below it near the botton of the nozzle of the dredging
pipe. On the bottom end of the spindle I place a cross bar or frame provided with
spikes or prongs.
The upward current of water causes the propeller to revolve and thus the
aforesaid spikes will tear up the hard surface and while agitating the spoil cause it
to be raised by the ascending current of water.
I also provide the nozzle or bottom end of the dredging pipe with a sleeve or
outside casing which leaves an annular space between the nozzle and sleeve by
this means when the pipe is lowered to the bed of the river or sea, the casing
or sleeve being carried down a little lower than the nozzle, the current of water
descending the annular space and entering the nozzle is first of all caused to
impinge on the bed of the river and by this means washes out or loosens the spoil
and causes it then to ascend the pipe with the current of water.

page_text: I make use of this sleeve either alone or in connection with the screw propeller
or turbine and revolving spikes.
When the pipe or nozzle is provided with a loose casing I cause the latter to
revolve by fitting the casing in the annular space between that and the nozzle with
webs or blades curved or placed obliquely. The current of water acting on these
webs causes the casing to revolve, and the bottom of the revolving casing being
provided with spikes or prongs or a cross-bar or frame with spikes, as these revolve
so the spoil is stirred up.
Or the sleeve may be loose on the bottom of the dredging pipe or nozzle so that
the nozzle is free to rise and fall in the sleeve. By fixing studs in the nozzle
fitting into spiral grooves in the sleeve when the nozzle is raised or lowered in
the sleeve it causes the sleeve to partly revolve and the bottom of the sleeve being
notched or provided with spikes or prongs as aforesaid it cuts into the bed and so
loosens the spoil that it may be raised by the current.
The long iron teeth on bottom of the nozzle may be hinged on spindles or shafts
at the bottom of the pipe, and operated by levers ropes or chains and so cause the
teeth to move as before, or to close or lift up after they have sunk into the bed of
the river to loosen the spoil.
To make a joint on or with the ground and the machine and to ensure the current
of water going down the annular space between the two pipes I place on the
bottom of the outer tube or nozzle an india rubber valve or flap. The rake or
spikes may be driven by a slide or telescope shaft so as to allow for the varying
depths of water; I prolong this shaft up through the top of the pipe and drive it
by a belt, wheel gearing or other suitable arrangement.
Dated this fifth day of January 1884.

page_text: "
I JAMES WELMAN of Poole in the County of Dorset, Engineer do hereby declare
the nature of said invention for "IMPROVEMENTS IN DREDGING MACHINERY and
in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement:-
My invention relates to improvements in that class of dredging machinery where
the material or spoil is raised by means of a current of water through a pipe or
pipes connected to a pump and having the lower end or ends lowered into the river,
estuary or sea so as to nearly touch the bed. In some cases the bed of the river
or sea to be dredged is a hard compact clay like material or a conglomerate mass
having looser material only on the surface and so prevents the raising of the
material or spoil by the current of water up the pipe described.
My invention provides a means of cutting through or breaking up the bed and
an agitation of the spoil so as to enable the current of water to raise it.
The means I adopt for effecting this are as follows:
Figure 1 of the accompany drawings is a longitudinal vertical section of so
much of a dredging machine constructed according to my invention as will be
necessary to explain the same as applied to a nozzle suitable for penetrating hard
or clayey ground, and Figure 2 is a similar view of a nozzle suitable for loose or
soft ground.
I enlarge the dredging pipe a at c a short distance above the nozzle b to any size
that may
from the nature of the material to be dredged be found necessary in
order to divert the current. In this enlarged part c of the pipe a I place for
example a screw propeller d having two or more blades or made in the form of
a continuous screw or it might be a turbine. I fix the propeller d on a suitable
spindle e provided with bearing f above the propeller and with a bearing g below
it near the bottom of the nozzle 6 of the dredging pipe a. On the bottom end of
the spindle e I place a cross bar or frame h provided with spikes or prongs i.
I also provide the nozzle or bottom end 6 of the dredging pipe with a sleeve or
outside casing k which leaves an annular space between the nozzle b and sleeve k
by this means when the pipe is lowered to the bed of the river or sea the casing or
sleeve being carried down as shown in the drawings a little lower than the
nozzle b and the pump is started, the current of water descending the annular
space and entering the nozzle b as indicated by the arrows is first of all caused to
impinge on the bed of the river and by this means washes out or loosens the spoil
and causes it then to ascend the pipe a with the current of water in the direction
indicated by the arrows and the said upward current of water causing the
propeller d to revolve and with it the shaft e and spikes i and thus the aforesaid
spikes will tear up the hard surface and while agitating the spoil cause it to be
raised by the ascending current of water through the nozzle b and pipe a to the
surface.
I make use of this sleeve either alone or in connection with the screw propeller
or turbine and revolving spikes. In the arrangement shown at Figure 2 neither
propeller turbine or rakes are used but the current action is similar to that before
described and similar letters of reference indicate like parts.
When the pipe or nozzle is provided with a loose casing or sleeve k I cause the
latter to revolve by fitting the casing in the annular space between that and the
nozzle b with webs or blades curved or placed obliquely. The current of water
acting on these webs causes the casing k to revolve the bottom of the revolving

page_text: casing being provided with spikes or prongs or a cross bar or frame with spikes; as
these revolve so the spoil is stirred up. Or the sleeve may be loose on the bottom
of the dredging pipe or nozzle so that the nozzle is free to rise and fall in the sleeve.
By fixing studs in the nozzle b fitting into spiral grooves in the sleeve when the
nozzle b is raised or lowered in the sleeve it causes the sleeve to partly revolve
and the bottom of the sleeve being notched or provided with spikes or prongs as
aforesaid it cuts into the bed and so loosens the spoil that it may be raised by the
current. The long iron teeth on bottom of the nozzle may be hinged on spindles
or shafts at the bottom of the pipe and operated by levers, ropes or chains and so
cause the teeth to move as before or to close or lift up after they have sunk into
the bed of the river to loosen the spoil.
To make a joint on or with the ground and the machine to ensure the current of
water going down the annular space between the two pipes I place on the bottom
of the outer tube or nozzle an india-rubber valve or flap.
The rake or spikes may be driven by a slide or telescope shaft so as to allow for
the varying depths of water; I prolong this shaft up through the top of the pipe
and drive it by a belt, wheel gearing or other suitable arrangement.
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
In dredging machinery the employment of a sleeve or outside casing at or near
the nozzle and extending somewhat below same whereby an annular chamber is
formed between sleeve and nozzle for directing the current of water in a downward
direction on to the ground the said annular chamber to be employed in such
machines in combination with a nozzle alone or in combination with a nozzle
having a revolving rake or cutter the latter being driven by a screw propeller or
turbine worked by the upward current of water caused by a pump above or
whether the said rake or cutter be driven by other means all substantially as
hereinbefore described with reference to the accompanying drawings together with
any mere modification thereof.
Dated this Fourth day of October 1884.
BREWER & JENSEN,
Agents for the Applicant.