IMPROVEMENTS IN DREDGING APPARATUS
Year: 1880

page_text: LETTERS PATENT to John Standfield and Josiah Latimer Clark, both of
6, Westminster Chambers, in the City of Westminster, for an Invention of
“IMPROVEMENTS IN DREDGING APPARATUS."
PROVISIONAL SPECIFICATION left by the said John Standfield and Josiah
Latimer Clark at the Office of the Commissioners of Patents on the
16th December 1880.
JOHN STANDFIELD and JOSIAH LATIMER CLARK, both of 6, Westminster
Chambers, in the City of Westminster. " IMPROVEMENTS IN DREDGING
APPARATUS."
This Invention has for its object improvements in dredging apparatus.
Our Invention consists of an improved form of dredging skip or excavator for
dredging and raising earth or other material from beneath the water or from the
holds of vessels, the bottom of wells, or similar positions.
In its general features it consists of a framework carrying a hemispherical or
hollow scoop which revolves on an axis, and also traverses backwards and forwards
within the frame.
up
The frame is lowered into the water by means of a chain with the scoop in an
inverted position, and when it reaches the bottom a detaching arrangement is
brought into action which liberates the first attachment between the chain and the
framework bringing another into action, so that when the chain is hauled its
first effect is to revolve the scoop on its axis, and to traverse it horizontally within
the frame so as to cause it to scoop up the earth, and when it has thus revolved
through a half circle and filled itself with earth, and when the scoop has arrived at
the horizontal position the further hauling on the chain raises both the scoop and
the framework to the surface, where it is emptied of its spoil, and the scoop being
again inverted it is lowered to the bottom as before.
The framework is formed preferentially of four vertical iron uprights connected
by crossed bars into a rigid system; these are brought together at the top and
rivetted to a crown plate. At about the middle of its height the frame carries a
pair of horizontal beams, one on each side, and from these beams two pairs of
One of these
hangers are suspended so as to swing vertically within the frame.
pair of hangers is suspended from about the centre of the beams, and the two arms

page_text: carry at their lower ends the bearings of the axis which carries the main scoop,
which scoop is therefore freer to swing horizontally through a certain are within
the frame. The second pair of hangers is suspended from the same beams, but
nearer their back ends, that is to say, the end from which the scoop traverses, and
they swing parallel to the first pair. They carry at their lower ends an axis
parallel to the axis of the scoop, and upon this axis there are placed a sheave and
a loose pair of plates slightly larger than the sheave, one on each side, which revolve
freely on the axis. This sheave carries the main chain, the use of which will be
described further on. As these hangers carry only the axis of the sheave and
plates they may with advantage be curved or bent in towards each other so as
nearly to meet. The first pair of hangers carry the axis of the scoop, which is of
the full width that the frame will admit. Upon each end of the axis of the scoop
is fixed a pulley attached to the scoop, and on each of these pullies is wound a
chain which is fixed to them, and makes about one turn round them; the other
ends of these two chains are carried up through the crown piece and are united into
one; their office is to turn the scoop bottom upward. In addition to these side
chains there is a main chain whose office is to turn the scoop over and fill it with
spoil; this chain also passes down through the crown piece, passes through the
sheave with loose plates, which swings upon the second pair of hangers, then winds
round the back of the scoop while in its inverted position, and is finally attached
to the back part of the scoop near its after edge. When this chain is pulled upon
it first causes the scoop to revolve on its axis and fill itself with spoil, the sheave
on the second pair of hangers pressing hard against the scoop, the friction being
reduced by the rolling of the two loose plates against the back of the scoop as it
rotates. When it is filled and has arrived at the upright position its further motion
is prevented by a stop, and if the chain be further hauled upon the whole apparatus
will be lifted bodily to the surface. On the other hand, if the two side chains be
hauled upon they will cause the scoop to rotate in the opposite direction till it is
inverted and emptied, its further motion being arrested by a stop. The whole
action of the apparatus then consists in lifting it by the side chains so as to invert
the scoop, these side chains being suspended from the main chain by a self
detaching slip hook; in this condition the frame is lowered to the bottom of the
shaft or space to be excavated. As soon as it reaches the bottom the four corner
frames rest on the surface, and the scoop also rests on the ground upside down.
At the same time the slip hook detaches itself leaving the side chains free. On
hauling up again the main chain alone now comes into action, tending both to
revolve the scoop and to lift the whole apparatus. As the leverages are equal one
half the strain tends to lift the weight and the other half tends to dig the cutting
edge of the scoop down into the ground; if the ground be soft the scoop will cut
into it and fill itself, but if it be exceptionally hard the downward cutting power
may be increased to any extent desired by causing tho main chain to act on the
scoop, not directly, but through the intervention of pulley blocks or cog wheels so
as to make the rotating effect greater than the lifting effect.
It has been stated that the scoop is not fixed rigidly in the frame, but is, by
preference, suspended from hangers so as to be free to swing to and fro across the
frame. The object of this is to give it a scooping movement forward. To effect
this the side chains pass through pulleys in the back of the frame so as to haul the
scoop backward at the same time that they invert it. In like manner the main
chain passes through a pulley in the fore part of the frame so as to draw it forward
on its hangers at the same time that they turn it upright and cause it to fill with
soil or other material. In addition to the traversing effect above described a further
effect of the same kind is produced by two chains, which are attached at one end
to the front of the frame, and at the other end to a pin or to pullies on the axes of
the scoop. As these axes rotate they wind up these chains and draw the scoop
forcibly from back to front.
In another form of the machine the frame work is made to carry two independent
scoops, and in this case it is preferable that they should scoop towards each other,

page_text: and that when both are turned upright and filled their two projecting cutting
edges may come into contact, or nearly so. In a similar way three or more scoops
may be fitted to work in a single frame. The framework may in some cases be
simplified into a single bow or bail, carrying the necessary pulleys and stops.
In lowering the apparatus it is important that the resistance it meets with in
sinking through the water should not make its descent so slow as to allow time for
the supporting chain to become slackened, for in this case the slip hoop would become
self detached, and the side chains then coming into action might turn the scoop
over before it reached the bottom, and the machine would come up empty.
To obviate this evil we employ a governor on the crane or windlass to prevent
the too rapid lowering of the chain.
We prefer the hydraulic governor of John Standfield, patented in 1861, No. 2979,
consisting of a number of blades rotating on a central spindle within a fixed cylinder
of water, the cylinder being provided internally with a series of fixed blades nearly
in contact with the rotating ones, which cause great friction and resistance to the
rotation of the blades; or, if preferred, the central spindle is held fixed and the
cylinder allowed to revolve. This apparatus is connected with the windlass by a
clutch or belt so as to run loose when the chain is being raised and to
resistance when it is being lowered.
oppose
The governor thus is so contrived that it weighs the power and both controls
and indicates the speed at which the apparatus descends.
In order to cause the soil to be perfectly emptied out of the scoop when the soil is
adhesive we form the scoop like an ordinary dredging bucket, and we make the
bottom with a loose flap or a flap hinged at the back, so that when inverted this
flap falls partially open and drops against a stop or stops in order that the jerk
may throw out the clay or other material from the scoop. When it is again brought
upright the flap falls into its place by gravity ready for another charge.
In dredgers which are drawn continuously along the sea bottom we apply a
revolving brush at the mouth of the dredge to sweep into it the things which it is
wished to collect. The periphory of the brush is made to revolve at a greater
speed than that at which the dredge itself moves. It is actuated by wheels
running upon the bottom, and coupled with the brush by toothed or other driving
gearing.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Standfield and Josiah Latimer Clark in the Great Seal
Patent Office on the 16th June 1881.
JOHN STANDFIELD and JOSIAH LATIMER CLARK, both of 6, Westminster
Chambers, in the City of Westminster. "IMPROVEMENTS IN DREDGING
APPARATUS."
This Invention has for its object improvements in dredging apparatus.
Our Invention consists first, of an improved form of dredging skip or excavator
for dredging and raising earth or other material from beneath the water, or from
the holds of vessels, the bottoms of wells, or similar positions.
In its general features it consists of a framework carrying a hemispherical or
semi-cylindrical hollow scoop which revolves on an axis, and also traverses back-
wards and forwards within the frame.
The frame is lowered into the water by means of a chain with the scoop in an
inverted position, and when it reaches the bottom a detaching arrangement is
brought into action, which liberates the first attachment between the chain and the
framework bringing another into action, so that when the chain is hauled up its
first effect is to revolve the scoop on its axis and to traverse it horizontally within
the frame, so as to cause it to scoop up the earth, and when it has thus revolved
through a half circle and filled itself with earth, and when the scoop has arrived at
the horizontal position, the further hauling on the chain raises both the scoop and
the framework to the surface where it is emptied of its spoil, and the scoop being
again inverted it is lowered to the bottom as before.
Figures 1 to 6 of the Drawings hereunto annexed shew various views of the
dredging skip.
The framework is formed preferentially of four vertical iron uprights A, A,
connected by crossed bars into a rigid system; these are brought together at the top
and rivetted to a crown plate B. At about the middle of its height the frame
carries a pair of horizontal beams C, C, one on each side, and from these beams
two pairs of hangers D and E are suspended so as to swing vertically within the
frame; one of these pairs of hangers D is suspended from about the centre of the
beams, and the two arms carry at their lower ends the bearings of the axis G
which carries the main scoop F, which scoop is therefore free to swing horizontally
through a certain arc within the frame; the second pair of hangers E is suspended
from the same beams, but nearer their back ends, that is to say, the end from
which the scoop traverses, and they swing parallel to the first pair. They carry at
their lower ends an axis H parallel to the axis of the scoop, and upon this axis
there are placed a sheave I and a loose pair of plates J, J, slightly larger than the
sheave, one on each side, which revolve freely on the axis. This sheave carries
the main chain, the use of which will be described further on. As these hangers
carry only the axis of the sheave and plates, they may with advantage be curved
or bent in laterally towards each other, as shown in Figure 3, so as nearly to meet.
The first pair of hangers D carries the axis of the scoop G, which is of the full
width that the frame will admit. Upon each end of this axis is fixed a pulley or
cam K attached to the scoop, and on each of these pullies is wound a chain, shown
in double light dotted lines, which is fixed to them and makes about half a turn
round them. The office of this chain is to turn the scoop bottom upward and
retain it in that position. The other ends of these chains are joined to a spreading
beam or butterfly nut L. A hook bar M screws through the spreading beam L and
is carried up through the crown piece B.
In addition to these side chains there is a main chain, shown in a heavy line with
alternate dots and dashes, whose office is to turn the scoop over and fill it with

page_text: spoil;
this chain also passes down through the crown piece, passes through the
sheave I with loose plates, which swing upon the second pair of hangers Ę, then
winds round the back of the scoop while in its inverted position, and is finally
attached to the back part of the scoop near its after edge at N. When this chain
is pulled upon it first causes the scoop to revolve on its axis and fill itself with
spoil, the sheave I on the second pair of hangers pressing hard against the scoop,
the friction being reduced by the rolling of the two loose plates J, J, against the
back of the scoop as it rotates. Whilst the scoop is filling the frame is kept from
moving by reason of the lower ends of the uprights A taking a hold of the ground.
When it is filled and has arrived at the upright position its further motion is pre-
vented by a stop, and if the chain be further hauled upon the whole apparatus will
be lifted bodily to the surface. On the other hand, if the two' side chains, shown
in double dotted lines, be hauled upon, they will cause the scoop to rotate in the
opposite direction till it is inverted and emptied, its further motion being similarly
arrested by a stop. The whole action of the apparatus then consists in lifting it
by the side chains so as to invert the scoop. These side chains are suspended from
the spreading beam L and the rod M, and the top of this rod M has a self detaching
slip hook O, the upper link R of which is permanently attached to the main lifting
chain (not shown in the Drawing). In this condition the frame is lowered to the
bottom of the shaft or space to be excavated. As soon as it reaches the bottom
the four corner frames A rest on the surface, and the scoop also rests on the ground
upside down; at the same time the slip hook O detaches itself leaving the side
chains free. On hauling up again the main chain which is permanently attached
to the link P alone now comes into action, tending both to revolve the scoop and to
lift the whole apparatus. As the leverages are equal one half the strain tends to
lift the weight, and the other half tends to dig the cutting edge of the scoop down
into the ground. If the ground be soft the scoop will cut into it and fill itself, but
if it be exceptionally hard the downward cutting power may be increased to any
extent desired by causing the main chain to act on the scoop, not directly but
through the intervention of pulley blocks or cog wheels so as to make the
rotating effect greater than the lifting effect. An arrangement of this kind is shown
in Figure 7.
The hook shown in Figure 9 engages under the collar Y, Figure 7, and forms a
convenient method of suspending the frame when at the surface and while the
inverting link is being attached. The links P and R are shown in the same
positions in Figures 1 and 2. This is done only so that the Drawing should not
occupy too much space.
It has been stated that the scoop is not fixed rigidly in the frame but is by
preference suspended from hangers D, D, so as to be free to swing to and fro across
the frame. The object of this is to give it a scooping movement forward. To effect
this more perfectly the side chains shown in double dotted lines pass over
pulleys S, S', in the back of the frame so as to haul the scoop backward at the
same time that they insert it. In addition to the traversing effect above described,
a further effect of the same kind is produced by two chains T, T, which are
attached at one end to the front of the frame and at the other end to a pin or to
pullies on the axes of the scoop; as these axes rotate they wind up these chains and
draw the scoop forcibly from back to front.
In another form of the machine the framework is made to carry two independent
scoops; and in this case they may either scoop toward each other, as in Figure 8,
or away from each other, as in Figure 7. In a similar way three or four scoops
may be fitted to work in a single frame, as shown in plan in Figure 10. The
framework may in some cases be simplified into a single bow or bail carrying the
necessary pulleys and stops.
In lowering the apparatus it is important that the resistance it meets with in
sinking through the water should not make its descent so slow as to allow time for
the supporting chain to become slackened, for in this case the slip hook would
become self detached, and the side chains then coming into action might turn

page_text: the scoop over before it reached the bottom, and the machine would come up
empty.
To obviate this evil we employ a governor on the crane or windlass to prevent
the too rapid lowering of the chain.
We prefer the hydraulic governor of John Standfield, patented in 1861, No. 2979,
consisting of a number of blades rotating on a central spindle within a fixed
cylinder of water, the cylinder being provided internally with a series of fixed
blades nearly in contact with the rotating ones, which cause great friction and
resistance to the rotation of the blades; or if preferred the central spindle is held
fixed, and the cylinder allowed to revolve. This apparatus is connected with the
windlass by a clutch or belt so as to run loose when the chain is being raised, and
to oppose resistance when it is being lowered.
The governor is so contrived that it weighs the power, and both controls and
indicates the speed at which the apparatus descends.
The chain which
made fast to the
scoops (shown in
In Figure 8 a different arrangement of the chains is shown.
inverts and empties the scoops (shown in double dotted lines) is
bottom of the scoop near the centre. The chains for filling the
dot and dash lines) are attached to the back of the scoops at N, and pass round the
sheaves U, and are united at the link V so as to form a bridle chain. On hauling
on to the main chain W the strain on the bridle chains X, X, is at first nearly
infinite, and causes the scoops to dig into the ground with great force, the power
diminishing as the link V is drawn up.
In order to cause the soil to be perfectly emptied out of the scoop when the soil
is adhesive, we form the scoop like an ordinary dredging bucket, and we make the
bottom with a loose flap or a flap hinged at the back so that when inverted this
flap falls partially open and drops against a stop or stops in order that the jerk
may throw out the clay or other material from the scoop. When it is again
brought upright the flap falls into its place by gravity ready for another charge.
It is evident that this improved dredging bucket may with great advantage be
adapted to the ordinary dredging machine or excavator so as to cause the buckets
to empty themselves perfectly as they become inverted. Figure 11 shows this
arrangement both a loose bottom and a hinged bottom as adapted to an ordinary
dredger.
Having thus described the nature of our said Invention, and the manner of
performing the same, we would have it understood that we claim,--
First. The construction of dredging apparatus, substantially as described with
reference to Figures 1 to 6.
Second. The construction of dredging apparatus, substantially as described with
reference to Figures 7, 8, and 10.
Third. The employment of a chain wound over the periphery of the skip or
bucket to turn it and cause it to fill, substantially as described.
Fourth. The employment of the self detaching arrangement by which we are
able to operate the dredger with only one chain.
Fifth. The employment of loose bottoms or flaps with the dredging scoops, sub-
stantially as and for the purpose herein before described.
In witness whereof, I, the said John Standfield, have hereunto set my hand
and seal, this Sixteenth day of June, in the year of our Lord One thousand
eight hundred and eighty one.
TAK
JOHN STANDFIELD. (L.S.)