IMPROVEMENTS IN THE CONSTRUCTION AND SUSPENSION OF DREDGER LADDERS FOR WORKING IN DEEP WATER
Year: 1884

page_text: PROVISIONAL SPECIFICATION.
I SAMUEL WILLIAMS of N° 130 Belvedere Road Lambeth in the County of Surrey
Lighterman do hereby declare the nature of my Invention for IMPROVEMENTS
IN THE CONSTRUCTION AND SUSPENSION OF DREDGER LADDERS FOR WORKING IN
DEEP WATER to be as follows:-
My Invention consists in the arrangement of quadrant grooves or radial bars as
may be best suited together with large grooved wheels for carrying counterbalance
weights of the ladder adjusting itself to a working position and also for berthing
itself on deck of vessel in a horizontal position to provide means whereby a
dredging ladder of great length can be worked in a vessel having a very short hull
and also to so arrange the shoot for catching the dredged material that it shall
adjust itself automatically to suit the varying angles of the dredging ladder when
working at different depths and also that the said shoot be cleared out of the way
also automatically by the ladder when the latter is hoisted up and deposited on
deck.

page_text: I SAMUEL WILLIAMS of N° 130 Belvedere Road Lambeth in the County of
Surrey, Lighterman do hereby declare the nature of my invention for IMPROVE-
MENTS IN THE CONSTRUCTION AND SUSPENSION OF DREDGER LADDERS FOR WORKING
IN DEEP WATER and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement and accompanying
drawings:-
-
The object of this Invention is to effect certain improvements in the apparatus
used for the purpose of Dredging either for obtaining material from below water
or for deepening existing channels for navigation or other purposes This apparatus
has for its object to provide means whereby a dredging ladder of great length can
be worked in a vessel having a very short hull so that the ladder can be raised
and deposited safely upon deck through a well in the centre of the vessel very
much shorter in length than the ladder itself and to so counterbalance the ladder
by means of an arrangement of ropes or chains and weights or counterbalance
that the strains on the hoisting gear due to the ladder are thereby lessened and so
that the automatic action of the said weights or counterbalances shall assist in
depositing the ladder upon the deck as before mentioned when the ladder is
hoisted and also to so arrange the shoot for catching the dredged spoil or
material that it shall adjust itself automatically to suit the varying angles of
the dredging ladder when working at different depths and also that the said
shoot be cleared out of the way also automatically by the ladder when the latter
is hoisted up and deposited upon deck.
"These improvements-consist First. In the construction of a Wrought Iron
framing or Gantry which I build in the hull on each side of the well in. the
centre of the vessel generally of the form shewn on the accompanying drawing
and marked A. upon which I support certain pulleys B. B. to carry the wire ropes
or chains in connection with the counterbalance C. C. I also support upon this
gantry pulleys D. D. for carrying the hoisting ropes or chains which are wound
upon a barrel E. of the ordinary description To the opposite end of the gantry
to the hoisting gear I attach segmental or curved grooves F. of either Iron or
Steel which guide the ladder back as it is being hoisted for deposition upon deck
by means of a block sliding in the groove on each side of the well attached by
means of a shaft to the ladder I also assist this operation by means of a radial
bar G fixed so that its extremity sweeps through the same arc as the segmental
curve.
Second. In the construction of the ladder H. which I make at its upper end
without any cross bracing between its sides down as far as its point of suspension,
so that the buckets in working may pass freely through the space so left and so
that I may also suspend in this space the shoot K. for catching the dredged spoil
in the most favourable position for the purpose I also about midway of the
length of the ladder between its points of suspension at each end attach on each
side a Pulley L. round which the wire rope or chain attached to the counterbalance

page_text: runs. The ends of this rope or chain I make fast the one to the upper end of the
Indder at or about the point marked M. the other to a girder N. carried upon the
gantry A. The point of suspension at the upper end of the ladder I form by a
shaft O. passing from side to side of the ladder and extending beyond it so that it
may pass through the extremities of the radial bars G. and enter at each side into
a block sliding in the curved groove F. At the end of the curved groove nearest
the well by means of either a latch or a bolt passed through I am able to lock the
point of suspension so that when the ladder is in this position it will if raised by
the hoisting gear only radiate about the shaft O. and not move back along the
grooves In this position it is held for dredging purposes for deep or shallow depths
upon the shaft O. I place a roller P. as shown round which in certain positions of
the ladder the bucket chain works I also at the lower end of the ladder on either
side of the bottom tumbler arrange a guard or flange Q. which prevents the buckets
from getting off the tumbler when the chain gets slack from wear or other
causes.
Third. In the construction and arrangement of the shoot K and its appendages
at the side for conveying the dredged materials from the buckets to the barges or
other vessels alongside the dredger I suspend this shoot from a shaft R. carried
by the gantry A. and I make this shoot so that it will hang freely between the
sides of the upper end of the ladder I connect this by means of a link to a
position in the ladder a short distance below the point of suspension 0 of the
ladder so that the shoot is pulled backward and forward by the motion of the
ladder so as to catch a good deal of spoil which would otherwise fall down the well
and be lost due to the buckets after leaving the top cant roll coming closer in
underneath the ladder when it is working in shallow water This link I also
construct so that when the ladder is hoisted for deposition upon deck it pushes the
shoot out of the way into the position shown by dotted lines upon the drawing
In order to connect this swinging shoot with the permanent shoot I fix on each
side of the well on the gantry by means of hinges a small shoot S which while
the operation of dredging is going on I bring forward so as to fill up the space
between the hanging shoot and the gantry A. on each side of the well but which
I shift back and secure out of the way so as to leave a clear path for the ladder
when I want to raise it upon deck The distribution of the dredged material to
either side is effected at will by the action of a tip shoot inside the shoot K. in
the ordinary manner.
Fourth. In the construction of the counterbalance C. C. which I make of such
dimensions that they balance any desired portion of the weight of the ladder.
The action of the apparatus is as follows.
Supposing the point of suspension O. to be fixed in a forward position in the
groove F as above described the ladder will then be in its proper place for dredging
and if the hoisting gear be put in operation the ladder will only radiate about the
shaft O. and in this condition the apparatus is adapted for dredging in either deep
or shallow water as the ladder is raised or lowered so it either pulls the shoot K.
more under itself or pushes it further off so as to adjust the position of K. to
the altered curve of the path of the returning buckets due to the angle at which
the ladder may be working.
When I desire to raise the ladder on deck I release the point of suspension O.
and commence raising the lower end of the ladder by means of the hoisting gear.
Immediately I do this the automatic action of the counterbalance C. C. commence
and so alter the centre of balance in the ladder itself by means of the wire ropes or
chains by which the system is connected as shown that the upper end of the ladder
travels back along the grooves F and on the radial bars G. allowing the lower
end of the ladder to pass up through the well at the same time that the ladder
passes back along the grooves it clears the shoot K out of its way by means of
the link before mentioned while the roller on the shaft O catches the bucket
chain and pushes it forward thus taking up the slack and prevents its hanging
in too great a loop under, the vessel as shown in dotted lines upon the drawing.

page_text: As an example of what I claim in this specification I can work a ladder of a
length of 91 feet between the centres of its top and bottom cant rolls through a
well hole 73 feet long in a hull 115 feet long 25 feet beam and 9 feet deep capable
of dredging to a depth of 60 feet of water the ladder being worked in its deepest
position at an angle of 60 degrees and I can raise the ladder in the manner before
mentioned through the well and deposit it upon the deck as shown upon the
drawing.
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
I hereby claim the application of the mechanical contrivance duly set forth and
declared as above for the purpose stated but I not confine myself to the precise
details and arrangements of construction as herein set forth as there may be varied
the peculiar characteristics and main features of my Invention being the same time
retained.
Dated this 9th May 1884.