Improvements in Dredging Cranes and Grabs.
Year: 1889

page_text: Date of Application, 11th June, 1889
Complete Specification Left, 11th Apr., 1890-Accepted, 7th June, 1890
PROVISIONAL SPECIFICATION.
Improvements in Dredging Cranes and Grabs.
SIDNEY MANTHORP COCKBURN 2 Princes Mansions Victoria Street Westminster
Engineer, do hereby declare the nature of this invention to be as follows:-
Adding to an ordinary crane a second jib, hereafter referred to as the "derrick
jib," pivoted at one end to the crane frame, and suspended at the other by a chain
from the fixed jib. One portion of the lifting barrel is made of greater diameter than
the remainder. From the portion of large diameter a chain is led over the fixed jib,
over the derrick jib, and secured to the sliding crosshead of the grab. From the
portion of small diameter a second chain is led over the fixed jib and secured to the
derrick jib. A tube or pole is secured to the sliding crosshead of the grab, and
passes thro' a hole in the head of the derrick jib. A chain is secured to the top end
of the tube or pole, led under a pulley on the head of the derrick jib, round a snatch
block connected to a steam cylinder or barrel, over a second pulley on the head of
the derrick jib and secured to the frame of the grab.
בד
11-
1
T
1000
COMPLETE SPECIFICATION.
Improvements in Dredging Cranes and Grabs.
I, SIDNEY MANTHORP COCKBURN, of 2 Princes Mansions Victoria Street, West-
minster in the County of Middlesex, Engineer 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 relates to dredging and excavating apparatus of the kind or class
wherein a scoop, bucket or grab having two or more pivoted sections, segments or jaws
is so arranged that it may be allowed to fall while open upon the mud or other material
to be removed and may then be closed and raised together with a load of the said
material.
In apparatus of this kind or class as hitherto constructed, the force required for
closing the sections or jaws of the scoop or bucket when lowered into the mud or
sand, is so applied that the said scoop or bucket has a tendency to rise, its weight
being partially overcome by the upward pull on the said sections or jaws. The result
is that the sections or jaws of the scoop or bucket, instead of being thrust further
into the mud or sand, simply exert a scraping action thereon and consequently do not
lift a full load.
"Now one object of my present invention is to so construct apparatus of this kind or
class that the force applied for closing the sections, segments or jaws of the scoop,
bucket or grab will be exerted equally in opposite directions and the said scoop,
bucket or grab will have no tendency to rise, but will dig into the mud or sand and
enclose a full load thereof.
For this purpose I provide a rod, tube or pole for carrying the scoop or grab,
and a ring, collar or frame arranged to move up and down relatively to the said rod
to operate the sections or jaws of the said scoop or grab and I connect the upper end
of the said rod, tube or pole with the sliding ring, collar or frame by means of a
chain or rope the loop or bight of which is passed around a pulley arranged to be
moved to and fro to effect the opening and closing of the scoop or grab. By these
means I provide for exerting a downward pull upon the rod tube or pole equal to the
upward pull upon the scoop or grab, whilst the full weight of the said rod or tubo
and of the scoop or grab is utilized for thrusting the jaws of the scoop or grab further
into the sand or mud.

page_text: Another object of my said invention is to provide for the use of the scoop or grab
at greater depths than is practicable with apparatus of the same kind heretofore
constructed, without using a rod or pole of inconvenient length. For this purpose
1 employ a crane provided with an additional or supplementary jib from which is
suspended the rod, tube or pole carrying the scoop or grab, and which is capable of
motion in a vertical plane about a suitable pivot. Moreover I so construct the
apparatus that when the said jib is turned about its pivot in one or the other direction,
the scoop or grab will be simultaneously raised or lowered relatively to the said
jib, thus increasing the rapidity with which the scoop or grab can be raised or
lowered.
In the accompanying drawings I have shown how my said invention may be con-
veniently and advantageously carried into practice.
Figure 1 is a side elevation of one form of my improved apparatus.
Figure 2 is a plan partly in horizontal section, showing parts of the said apparatus.
Figure 3 is a front elevation partly in vertical section showing the arrangement of
the pulleys at the ends of the two jibs.
Figure 4 is a front elevation of the scoop, bucket or grab, showing the arrangement
of the chain-drums for opening and closing the segments or jaws thereof.
Figure 5 shows a detail of construction hereinafter referred to.
Figuro 6 is a side elevation, and
Figure 7 a front elevation illustrating another form or modification of my
apparatus hereinafter described.
Like letters indicate corresponding parts throughout the drawings.
A is the turntable of the crane, which may be secured upon the deck of a barge
or upon any other suitable foundation. B is the frame of the crane, C is the fixed
or stationary jib which is connected at (to the turntable A and the upper end of
which is connected with the frame B by suitable ties or trusses D in the usual
manner.
E is a supplementary jib which I will hereinafter term the "falling jib," and
which is pivoted at E¹ to the frame B, and works in an opening in the jib C. To
the free end of this jib is attached one end of a chain E, which is passed over a
pulley (at the top of the jib C and around a drum F the axle of which serves as
the pivot for the falling jib E; and the other end of this chain is wound upon and
secured to a drum G provided with suitable means whereby it may be rotated by
manual or other power to raise and lower the said falling jib.
H is a rod, tube or pole which carries at its lower end the scoop, bucket or grab.
I find it advantageous to use a grab having two segments or jaws I, I pivoted at I, I',
to a frame J fixed on the lower end of the rod or tube H. Each of the segments or
jaws I is connected by links K with a ring or collar L which is fitted to slide freely
up and down upon the rod or tube H, when operated as hereinafter described, to open
and close the said segments or jaws I of the scoop or grab. The rod or tube H is
arranged to move up and down in the free end of the falling jib E, an anti-friction
roller E being provided at the extremity of the said jib to guide the said rod or
tube. A chain M is connected at one end to the ring or collar L and is passed over
a pulley N carried by the said jib E, and then over the drum F. The other end of
this chain is secured to and wound upon the drum G, which when rotated in one or
the other direction, will raise or lower the rod or tube H in the falling jib E. The
said rod or tube will therefore be raised and lowered relatively to the jib E while the
latter is being raised or lowered relatively to the jib C.
To provide for opening and closing the segments or jaws of the scoop or grab, and
for counter-acting any tendency to lifting of the scoop in the operation of closing
the same, 1 provide the following device, viz. -A chain P is attached at one end
to the upper end of the rod or tube H and is passed around a pulley P¹ and then
around one of the sheaves Q₁ of a pulley block Q which is also provided with
another sheave or pulley Q. The said chain P is also passed around a pulley P'
and is wound upon and secured to a drum R carried by the frame J of the scoop
or grab. The axle of the drum R has formed'or fixed thereon two other drums R

page_text: which are preferably of smaller diameter than the drum R, and upon which are
wound chains S attached at one end to the sliding ring or collar L and secured
at the other end to the said drums R¹ in such a manner that when the chain P is
unwound from the drum R, the chains S will be wound upon the drums R¹, and
vice versa but the winding and unwinding of the chains $ will take place more
slowly than the winding and unwinding of the chain P, the drums Ŕ being of
larger diameter than the drums R'. Great force can therefore be exerted through.
these chains for closing the scoop or grab.
Around the pulley of the block Q is passed a chain T one part of which is also
passed over a grooved pulley F¹ and is wound upon and secured to a drum U which
is connected with its axle by means of a suitable friction clutch and is provided with
any convenient means for rotating it, such for instance as a worm-wheel and screw..
The other part of the chain T is passed under and around the grooved pulley F' and
is attached to one of the tie rods D at the point T¹ or to any other convenient part
of the apparatus.
The operation of my improved apparatus above described is as follows, that is to
say By unwinding the chain T from the drum U the chain P is slackened to
permit the opening of the sections or jaws I of the scoop or grab by the descent of
the rod or tube H under the action of gravity. The drum G is then rotated in the-
proper direction to unwind the chains E, M thus simultaneously lowering the jib E
and rod or tube H relatively to the jib C, and also the said rod or tube H relatively
to the said jib E, and causing the scoop or grab to descend very rapidly until it comes
in contact with the mud or other material to be removed. The drum U is now
operated to wind up the chain T, thus drawing the pulley block Q towards the
pivoted extremity of the jib E tightening the chain P and lengthening the loop of
the said chain which passes around the pulley Q and unwinding more or less of the
said chain from the drum R.
The drums R, R¹ are thus caused to revolve and wind up the chains S, whereby
the sliding ring or collar L is drawn towards the frame J and the segments or
jaws of the scoop thus closed.
It will be seen that since the chain P extends from the drum R around the
pulleys P, Q, P¹, to the upper end of the rod or tube H and both the said drum.
and the rod or tube are securely connected with the frame J, any tension exerted
by the pulley block Q on the loop of the said chain P will cause the application to
the rod H of equal forces acting in opposite directions consequently no effect will be
produced tending to raise the scoop or grab bodily from the ground, whilst the jaws.
of the scoop will be caused to dig into the ground and take up a full load of mud
or other material to be excavated.
It is obvious that, in certain cases, especially where the dredging or excavating has
only to be effected at a small depth, the movable or falling jib E may be dispensed
with, the pulley block Q and the various pulleys required being arranged upon the
main jib C.
Moreover the chain T, instead of passing in a loop around the pulley Q', may be
connected directly to the pulley-block Q. This arrangement is not, however, so.
advantageous as that hereinbefore described, as, in the movement of the jib E, the
partial winding and unwinding of the chain T around the drum F would tighten
and slacken the same, and be liable to partially open the sections or jaws of the
scoop or grab. By the use of a looped chain passed around the said drum F in
opposite directions, as shown one part of the said loop is wound on the drum.
whilst the other part thereof is unwound from the said drum and vice versa, the
segments or jaws of the scoop are therefore unaffected by the winding and
unwinding of the chain T caused by the movements of the jib E about its pivot.
I sometimes attach the pulley-block Q to the piston or ram of a steam or pneumatic
or hydraulic cylinder, in which case I dispense with the chain T and drum U. This
cylinder may be mounted upon the jib E or may be otherwise suitably arranged.
In another form or modification of my apparatus, I employ a steam or pneumatic

page_text: or hydraulic cylinder for closing the scoop or grab, the valve of which cylinder can
be controlled by the operator by any convenient means.
In Figures 6 and 7 I have shown my improved apparatus provided with means
for closing the scoop or grab by hydraulic power. A hydraulic cylinder is, in this
case, secured, in the lower end of the rod or tube H and communicates, by a pipe or
passage within the said rod or tube, with a flexible pipe V connected at its upper end
to the upper end of the said rod or tube and at its lower end with a pipe W carried
by the movable or falling jib E and connected with an accumulator er pressure-main.
The said hydraulic cylinder is, moreover, similarly connected with the exhaust. The
ram Y of the hydraulic cylinder is connected to the pivoted sections or jaws I of the
scoop or grab by the links K, the cross-head J₁ to which the said links are con-
nected being fitted to slide up and down upon the said frame J. The chain M is
connected to the head of the ram Y; therefore, when the weight of the scoop and its
rod H is sustained by the said chain, and the hydraulic cylinder is opened to the
exhaust, the said ram will be raised and thus caused to open the jaws of the scoop
or grab. Moreover when the scoop or grab is resting upon the mud or sand and
finid under pressure is admitted to the hydraulic cylinder, force will be applied
equally in opposite directions to the rod or tube H and to the ram Y and the
whole weight of the scoop or grab and its rod or pole will be utilized for forcing
the said scoop or grab, while it is closing, further into the mud or sand.
It is evident that I can employ steam or pneumatic power for closing the scoop
or grab in a manner substantially similar to that illustrated in Figures 6 and 7.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I wish it understood that
I claim
First. A dredging or excavating apparatus wherein a scoop, bucket or grab is
carried by a vertically movable rod, tube or pole, and which is so constructed that
the force applied for closing the said scoop, bucket or grab will be exerted equally
in opposite directions, for the purpose above specified.
Second. A dredging or excavating apparatus of the kind or class herein before
described, wherein a chain or rope is connected at one end to the top of the
vertically movable rod, tube or pole, and at its other end to the sections or jaws of
the scoop, bucket or grab, and is passed around guide pulleys and around a pulley
provided with suitable means for moving it to and fro substantially as hereinbefore
described for the purposes specified.
Third. A dredging or excavating apparatus of the kind or class herein before
described, comprising a crane provided with a pivoted arm or jib the free end of
which is suspended from the ordinary or fixed jib, for the purpose above specified.
Fourth. A dredging or excavating apparatus comprising a scoop, bucket or grab
carried by a vertically movable rod, tube or pole which is suspended from a pivoted
arm or jib, and suitable means for turning the said jib about its pivot in one or the
other direction and simultaneously raising or lowering the scoop, bucket or grab
relatively to the said jib, for the purpose above specified.
Fifth. The improved apparatus constructed substantially as described with reference
to Figures 1 to 5 of the accompanying drawings, and operating as, and for the
purposes above specified.
Sixth. The modification of my invention wherein I provide a steam or pneumatic
or hydraulic apparatus for closing the scoop, bucket or grab, substantially as described
with reference to Figures 6 and 7 of the drawings.
נ..
101
S. MANTHORP COCKBURN.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.