Improvements in Grab Buckets or Diggers for Dredging and other Purposes.
Year: 1888

page_text: Date of Application, 12th Nov., 1888
Complete Specification Lelt, 12th Aug., 1889-Accepted, 21st Sept.. 1889
PROVISIONAL SPECIFICATION.
Improvements in Grab Buckets or Diggers for Dredging and
other Purposes.
I, HENRY GRAFTON, of 26 Willes Road, Kentish Town in the County of Middlesex,
Engineer, do hereby declare the nature of this invention to be as follows :—
My Invention relates to improvements in the grab bucket or digger for dredging
and other purposes forming the subject of an earlier application for Letters Patent
dated February 8th 1888, No. 1927 and my present improvements have for their
object, first to so arrange the catches by which the "abutment" is held down with
relation to the said abutment that the act of disengaging the catches will not
necessitate any, or at all events but a very slight, downward motion of the abutment
in the frame and to simplify the construction and operation of the said catches and
to raise them as far as possible above the ground so as to avoid clogging; secondly
to simplify, and reduce the cost of, the construction of the apparatus; thirdly to adapt
the suspension tube by which the grab is hung up at the jib-head to partake in all
oscillatory motions of the chain so as to preserve constant the relative position of the
acting flange of the tube and the hanging up catches notwithstanding the swinging
motion of the bucket due to the slewing of the crane and thus admit of more rapid
working.
The first and second objects are accomplished by pivoting the catches at a point in,
or nearly in, the line of strain so that the acting face of the catch may be concentric
or nearly so with its centre of motion. These catches are pivoted so as to swing
outwards from the side-members of the frame and they are so situated as to engage
with the abutment slides at about their highest part. To ensure simultaneous motion
of the catches they may be connected together by vertical rods and levers mounted
on the top cross-member of the frame, except when a rock shaft is used, as described
in another application of even date herewith.
When the said catches are to be thrown out of engagement by weights, I make the
weights slide upon the vertical rods attached to the catches and cause the sliding
cross-head to act on these weights at the latter part of its ascent so as to allow the
weights to act on the catches only at required times.
The vertical members of the framework of the apparatus are of cylindrical section
and may be tubes fitted at their ends into the top and bottom cross-members and
traversed by tie rods or bolts. The slide blocks of the abutment and cross-head
would partly embrace, and slide on these vertical members.
The suspension tube closely fits the hoisting chain and is hung on two axes at
right angles to each other or on a ball and socket or other universal joint.
My Invention has further for its object to adapt all single chain grabs used for
unloading grain and other cargoes in bulk to descend easily through a ship's
hatchway.
This I accomplish by furnishing the bucket-jaws with curved projections at or
near the corners, such projections being preferably formed by plates of the proper
form affixed to the ends of the bucket jaws.
They are somewhat in the form of (but do not act as) tusks or tines being curved
to the same curvature as the bucket jaws and overlapping or embracing the opposite.
jaw when the jaws are closed.
When the bucket is in the open position, the projections curve inwards below the
mouth of the open bucket and act as fenders to guide the bucket through the hatchway
and prevent the edges of the bucket jaws catching upon the coamings of the hatchway

page_text: going down. They also serve to prevent the edges of the bucket scraping upon the
floor of the hold when the cargo is nearly all discharged.
Dated this 12th day of November 1888.
H. GRAFTON.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.
COMPLETE SPECIFICATION.
Improvements in Grab Buckets or Diggers for Dredging and
other Purposes.
I; HENRY GRAFTON, of 26, Willes Road, Kentish Town, 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 improvements in the grab bucket or digger for dredging
and other purposes forming the subject of previous Letters Patents granted to me
dated February 8th 1888, No. 1927; and my present improvements have for their
object, first, to so arrange the catches by which the "abutment" is held down, with
relation to the said abutment, that the act of disengaging the catches will necessitate
but a very slight downward motion of the abutment in the frame, and to simplify the
construction and operation of the said catches and to raise them as far as possible
above the bucket jaws so as to avoid any chance of the catches becoming clogged
when the grab bucket is working in very soft mud; secondly, to simplify and reduce
the cost of the construction of the apparatus; thirdly to adapt the suspension tube
by which the grab is hung up at the jib-head, to partake in all oscillatory motions
of the chain so as to preserve constant the relative position of the acting flange of the
tube and the hanging up catches, notwithstanding the swinging motion of the bucket
due to the slewing of the crane, and thus admit of more rapid working.
The first and second objects are accomplished by pivoting the catches to the main
frame at a point in, or nearly in, the line of strain and at a point above the abutment
when the latter is in its lowest position in the frame so that the catches will engage
with the abutment slides at about the highest part of the latter, the catches being
arranged to swing outwards from the side members of the frame. The catches are
so weighted that they tend to fall inwards and engage with the abutment slides.
They are so connected together and actuated that both must move together. They
are thrown out of engagement by a weight or weights acting at the proper moment
in opposition to the self-engaging tendency of the catches, the sliding cross-head
being arranged to act on the weight or weights and prevent the action thereof on the
catches at the latter part of its ascent so as to allow the disengagement of the catches
to be effected only at required times.
The third object is effected by making the suspension tube closely fit the boisting
chain and hanging it on two axes at right angles to each other or on a ball and
socket or other universal joint.
My Invention has further for its object to adapt all single chain grabs used for
unloading grain and other cargoes in bulk to descend easily through a ship's
batchway. This I accomplish by furnishing the bucket jaws with curved projections
preferably formed by plates of the proper form affixed to the ends of the bucket
jaws, which when the bucket is in the open position curve inwards below the mouth
of the open bucket and act as fenders to guide the bucket through the hatchway,
They also serve to prevent the edges of the bucket scraping upon the floor of the hold
when the cargo is nearly all discharged.
Reference is to be had to the accompanying drawings forming part of this
specification wherein figure 1 is a front elevation of the improved grab bucket closed,
parts being broken away to shew the details more clearly. Figure 2 is a horizontal
section, taken just above the retaining catches for holding down the abutment.

page_text: Figure 3 is a view of one of the weight actuated retaining catches out of engagement
with the abutment. Figure 4 is a central cross-section of the bucket. Figure 5 is
a front view of a slightly modified arrangement in which a single weight acts to
throw both of the retaining catches into position of engagement. Figure 6 is a
part sectional elevation of the suspension tube and hanging up catches engaged
thereon. Figure 7 is a plan of the suspension tube. Figure 8 shews the hanging up
catches disengaged from the suspension tube. Figure 9 is a view of the bucket open
shewing the action of the horns for guiding the open bucket down through a
vessel's hatchway. The same letters of reference indicate the sanie parts in all the
figures.
A A are the bucket jaws hinged at a to the main frame B and connected to a
vertically sliding crosshead C by links D jointed to the jaws at d and to the
crosshend at c, all as described in the specification of my aforesaid patent. In
figures 1 to 4, the vertical side members B of the frame are steel tubes fitted into
sockets in the top and bottom transoms B1 B2 and traversed by tie bolts b
whereby the whole frame is rigidly secured, such tubes affording greater transverse
strength than the two separate angle irons shewn in my previous patent and in
figure 5.
The hoisting chain E may act on the jaws through multiple purchase gear, as in
figures 1 and 4, or gear without purchase, as in figure 5. In either case this gear
reverses the direction of the pull of the chain and acts as an "abutment" fulcrum or
point of resistance for converting the upward pull of the chain into a downward
pull of the cross head. In figures 1 and 4, the abutment is constituted by the barrel
axle the chain E being attached to and wound on the part F of the barrel and upon
itself and branch chains E¹ (formed of a single length of chain, the middle portion of
which lies in a cross-passage through the middle part F of the barrel so as to equalize
the strain) are wound (in the reverse direction to chain E) on the parts F¹ of the
same barrel of less diameter than the part F, the chains E¹ being connected to
the sliding crosshead C. The barrel turns loose on an axle H which is fast to the
shoes H' fitted to slide up and down the side members B of the frame. The barrel
axis is retained at proper times at the lower part of the frame by the self-acting
retaining catches next described. These retaining catches are self-engaging and are
so acted upon that when engaged with the abutment they tend to fall out of
engagement but are prevented from doing so by the strain on them, their disengage-
ment being permitted only when the strain on them is relieved. These catches I are
pivoted at to the vertical members of the frame in position to engage by their nibs i¹
with notches in the shoes H¹ when the latter descend to their lowest position in
the frame. When thus engaged the abutment is retained at the lower part of the
frame, as shewn in figures 1, 4, and 5. These catches are caused by their own
weight, to fall into position of engagement except when the bucket is nearly closed
at which moment another weight or weights, acting in the opposite direction to the
first, come into action. In order that the action of the two catches shall be
simultaneous and equal at the two sides of the bucket they are connected together as
hereinafter described. In figures 1 to 4, the catches have arms I¹ projecting towards
each other and connected to rock levers L by coupling rods K jointed to arms I'
and to the outer ends of the rock levers L which are pivoted at / to the top
transom B of the frame and are connected together at their inner ends ¹ by a pin
and slot. Jare tubular weights sliding on rods K and having flanges; at their
upper ends projecting into the path of a projecting part c¹ on the sliding cross-head C
so that when the latter is raised in the frame, as shewn in figure 8, it catches under
said flanges and carries up with it the weights J. In this the open position of the
grab bucket the weights J are inoperative and consequently the catches I are caused
by their own weight, to assume the position of engagement shown in figure 1. This
they do immediately they are relieved of the weights J and remain in that position
so long as the bucket is open except that when the abutment descends alone in the
frame the catches I are pushed back by the shoes H³, the catches then falling into

page_text: engagement with said shoes, as shewn in figure 1. This descent of the barrel or
abutment occurs when the grab bucket has been lowered in the open position for the
purpose of digging, the barrel then descending to the position shewn in figure 1
whilst the sliding crosshead C is held up in the frame, as shewn in figure 8, by the
open jaws A resting on the ground. As the crosshead is drawn down in the frame in the
act of closing the bucket, the weight J are allowed to rest upon shoulders of rods K
and they then act in opposition to, and are ready to overcome, the self engaging
tendency of the catches I, the relative arrangement being such that they come into
operative position only when the cross head has beon so far drawn down that the
bucket jaws have been sufficiently closed to obtain a good grip of the ground so that
the upward pull on the chain E will put considerable pressure on the contacting
faces of hand. Owing to this strain on the retaining catches, the weights J are
unable to assert their power until the hoisting chain E is relieved of strain by being
slackened out whilst the bucket is hung up or landed whereupon the weights J
prevail and throw the catches 1 out of engagement with the shoes H', as shewn in
figure 3, thus permitting the barrel or abutment to be drawn up in the frame by a
hoisting motion of the chain E for the purpose of opening the bucket.
In figure 5, the coupling rods K are jointed to a common disc L* pivoted on the
upper transom B and said disc is acted on by a single weight J✶ on a lever arm
pivoted concentrically with the disc and free to move on the same axis independently
of the disc, to an extent limited in one direction by a striking piece * on the lever
playing in a gap in the edge of the disc and bearing on a shoulder * of the disc
when the weight is in its operative position. The weight is rendered inoperative by
being lifted at the proper moment by a projecting part on the sliding cross-
head C, the action whereby the retaining catches are thrown into, and out of, engage-
ment being precisely similar to that above described.
For the purpose of opening the jaws by hanging up the grab to the jib-head, the
frame B is provided with catches P at top which when the grab is raised in the
closed position (see figure 1) strike against and engage on a flanged tube Q hung
just below the jib head and through which tube the hoisting chain E freely passos,
as shewn in figure 7. When the grab is thus supported by the catches P and the
hoisting chain E is sufficiently slacked off, the retaining catches I are free to be
thrown out of engagement with the abutment in the manner above described. The
grab jaws may then be opened to discharge the load by again winding up the hoisting
chain at the crane, as in hoisting.
The catches P are constructed and operated in precisely the same way as those
described in my previous patent aforesaid, that is to say they normally tend to fall
into position for engagement with the tube Q but are so acted on by the sliding
crosshead C, as shewn in figure 8, that they tend to fall off the flanged tube Q and do
fall off immediately they are relieved of the weight of the grab. This self ongagement and
self disengagement of the catches P is effected by pivoting the catches on axes p and
providing them with horizontal outwardly projecting tail pieces p' which act as
weights tending to throw the catches outwards. The catches are fast on their axes p
and upon the latter are loosely mounted tumbler weights Rhaving shoulders r on
their bosses which engage with cross-pins in the axes p so as to form a sort of
clutch which permits limited independent motion of the tumbler weights and of
the catches. The tumbler weights R respectively act in opposition to, and overcome,
the tail weights p', except when the tumbler weights Rare lifted by the cross head,
as shewn in figure 8, whereupon the tail weights p' disengage the catches from the
tube as soon as the said catches are relieved of the weight of the grab. The
passage through the tubo Q and the passage through the top-transom B' fit the
chain E closely enough to ensure that the tube Q shall be always centred with regard
to the catches P; and in order to ensure the two catches P always bearing an equal
amount of weight, notwithstanding lateral swinging of the bucket in the act of
slewing the crane, the tube Q is hung by a pair of gudgeons q in a ring S which is
hung by a pair of links or chains & from the jib head, the gudgeons y being in a

page_text: plane at right angles to the plane of the links or chains s. The gudgeons g therefore
allow the tube to swing in a direction at right angles to the direction of swing
permitted by the links or chains s, the two together forming a sort of universal
connection permitting swing in any direction so that the plane of the flange of the
tube Qupon which the catches P engage will always be perpendicular to the direction
of the chain E.
In order to adapt the bucket (when used for unloading grain and other cargoes in
bulk) to descend more easily in the open position through a ship's hatchway, the
bucket jaws A are furnished with curved projections T T at each end, such projections
being preferably formed of plates bolted the one T to the outside and the other T¹ to
the inside of the end of the bucket jaw so that when the bucket is closed they will
overlap the opposite jaw These projections are somewhat in the forin of (but do not
act as) tusks or tines, being curved so as to practically form continuations of the
curved outline of the bucket jaws, and when the bucket is open, they curve towards
each other below the bucket, as shewn in figure 9, and act as fenders to guide the
bucket through the hatchway and prevent the edges of the bucket jaws catching
upon the coamings V of the hatchway in going down. In this figure, the said guides
or fenders are shown as striking against the coaming of the hatchway. They also
serve to prevent the edges of the bucket scraping the floor of the hold when the cargo
is nearly all discharged.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is ;
1. In a single chain grab bucket whereof the jaws are both opened and closed by
an upward motion of the hoisting chain and whereof that part which acts as an
"abutment" or "fulcrum "-(to resist and reverse the effect of the pull of the chain)
is movable up and down the frame, the combination with such vertically movable
part or abutment, of catches pivoted to the main frame and adapted to engage with
the abutment and prevent it rising in the frane, the said catches being so weighted
that when disengaged they assume the position for engagement and of a weight or
weights acting on the catches in opposition to and overcoming the self engaging
tendency of the catches whenever said catches are relieved of the strain due to the
weight of the grab, substantially as specified.
2. In a single chain grab bucket whereof the jaws are both opened and closed by
an upward motion of the hoisting chain and whereof that part which acts as an
"abutment" or "fulcrum" (to resist and reverse the effect of the pull of the chain)
is movable up and down the frame, but is retained at the lower part of the frame
in order that it may act as an abutment, by catches each acted on in opposite
directions by weights as described, the combination with the weight or weights
tending to disengage the catches of the sliding cross-head or other part movable up
and down therewith, such cross-head or equivalent part acting on the said weight or
weights in such manner as to render them inoperative when the cross head is nearly
raised and permit them to act on the catches in opposition to the self-engaging
tendency only when the cross-head has been partly drawn down in the frame, as
specified.
3. A suspension tube having a flange or head at its lower end for engagement
with the hanging up catches of the grab, said tube permitting the free passage of the
chain but fitting closely around it so as to be centred thereby with regard to the
catches, the tube being so hung as to be free to swing in any direction and so
participate in the swinging of the grab so as to ensure both of the hanging up catches
when engaged therewith supporting the weight of the grab as specified.
4. The combination with the bucket jaws of pairs of curved projections or guards
forming continuations of the curved outline of the bucket jaws and affixed to the ends
of the jaws so as to overlap the opposite jaw when the bucket is closed, the said
guards projecting towards each other when the bucket is open and presenting their

page_text: convexly curved edges in advance of the bucket so as to act as guides in lowering
the bucket through a ship's hatchway and prevent the bucket catching on the coamings
of the hatchway, as specified.
וי די
H. GRAFTON.
By A. M. & Wm. Clark,
.53, Chancery. Lane, London, Patent Agents.