improvements in grabs buckets or skeps foringging or cargoes for excavating or dredging and for other purposes
Year: 1886

page_text: Date of Application, 10th Nov., 1886
Complete Left, 5th Aug., 1887
Complete Accepted, 1st Nov., 1887
RESERVI
My invention relates to improvements in grabs buckets or skeps for raising or
discharging grain or other cargoes for excavating or dredging and for other purposes.
The grab bucket or skep of my invention hereinafter indiscriminately called "the
grab" is made to open and close by the mere operation of raising and lowering it and is
constructed strongly in a simple form to withstand the rough usage that such machines
generally receive and which often proves fatal to mechanism of a more complicated
nature.
1
The grab proper which may be of any form to suit the requirements of the work is
made in two parts each pivotted at its inner corners to a strong "inner" frame and at
its outer corners to suspension links pivotted to a crosshead which slides in the inner
frame. This crosshead has attached to it the closing chains and engages with the
retaining rods attached to the "outer" frame. The inner frame also carries the
barrels to which are attached the lifting and closing chains and is provided with catches
for the purpose of holding back the crosshead and so keeping the grab open until they
are released by wedge-shaped disengaging pieces attached to the outer frame. This
outer frame slides adjacent to the inner frame being suitably guided and has retaining
rods which engage with the crosshead and is provided with a means of suspending
the grab independently of lifting chain. In grabs controlled by two chains this is
accomplished by a chain leading away parallel to lifting chain and in those operated
by a single chain the outer frame is provided with a headed hollow spindle or other
suitable arrangement which engages with catches suspended from some convenient
structure. These catches may themselves be suspended from this structure and
operated by hand or contained in a "block" or other convenient apparatus similarly
suspended and operated either by hand or automatically.
The mode of operation of the grab with suspended block having catches operated by
hand is as follows:-
:-
Suppose the grab to be closed and to be being drawn up with a load. The head
of spindle of grab passes up the suspended block pressing back the block catches.
When the head passes above these catches they fall back again and so prevent its
return. The lifting chain is then lowered and the head rests on these block catches.
By this means the outer frame is suspended whilst the chain barrel and inner frame

page_text: are lowered. The heads of retaining rods come in contact with the crosshead and keep
it back the effect of this being that the outer ends of grab proper are held back by
their suspension links whilst the inner corners descend with the inner frame thus
opening the grab proper and discharging its contents. By the time the grab is fully
opened the grab catches on inner frame have descended far enough to allow the ends
of crosshead to pass them and have fallen back again into their places and the lowering
of chain is stopped. The grab now hangs suspended. On again lifting the lifting
chain the grab catches engage with the crosshead to which are attached the closing
chains and thus prevent the grab closing so that in this position it is lifted with the
chain until the disengaging pieces rest on the horns of catches thus taking the weight
off the block catches which are now withdrawn by hand so that the whole weight
is again carried by the lifting chain which is now lowered. As long as the weight of
crosshead suspension links etc and pull of closing chains act on the ends of crosshead
they cause them to grip firmly the grab catches so that although the weight of outer
frame acting through disengaging pieces on horns of grab catches tends to open them
it has not sufficient power to do so until the grab proper rests on the ground or any
other sufficiently resisting medium. Then the weight of crosshead etc etc is taken
off the catches so that the disengaging pieces acting by the weight of frame and also
the inertia acquired in descending wedge open the grab catches and keep them open.
The lifting chain is now lifted and as the ends of crosshead now are free the closing
chains close the grab thus filling it and when it is closed the lifting chain draws the
whole up and the above actions are repeated.
In some cases I work the block catches automatically. In carrying out this
part of my invention I provide a frame or "block" having two or more catches of
such a construction as will easily admit the head of grab but will prevent its return
until they are liberated. This liberation is effected by a weight or weights or springs
which tend to keep the catches open. These catches are put into action in some cases
by adjustable striking pieces on inner frame acting on a ring connected by suitable
levers to block catches and in other cases by a large link or other suitable attachment
to lifting chain acting on a crossbar suitably connected to block catches.
The action of the block catches which are put into action by striking pieces on inner
frame is as follows, supposing the loaded grab to be rising as before the weights or
springs keep the block catches open. As the head of spindle of grab rises past these
catches the striking pieces come in contact with the ring raising it up so that hy
the time the head of grab has passed the catches they are free to fall into action the
striking pieces preventing the weights or springs from withdrawing them. When the
chain is lowered the weight of outer frame of grab rests on these block catches and so
prevents their withdrawal by the weights or springs but when the grab proper and
inner frame rise after having discharged its contents and the outer frame is lifted by
the disengaging pieces coming into contact with the grab catches as hereintofore
described the weights or springs withdraw the block catches the striking pieces not
now being high enough to prevent this so that the grab may be lowered as before.
The action of the block catches which are put into action by a large link or other
suitable attachment to lifting chain is the same as the foregoing except the levers
connected to the block catches are lifted by a crossbar attached to them instead of being
pushed up by the striking pieces.
In some cases I provide a weight fixed to the lifting chain of such a shape as will
easily pass through the suspended block and in such a position that when the grab
rests on the material after having been quickly lowered this weight will follow it up
and strike a blow on the top of spindle thus aiding the weight of outer frame in freeing
the grab catches.

page_text: JOHN GILL, 416 Fulham Road, London S.W. 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 Grab Buckets or Skeps for raising or
discharging grain or other cargoes for excavating or dredging and for other purposes.
The Grab Bucket or Skep of my invention hereinafter indiscriminately called "the
Grab" is made to open & close by the mere operation of raising & lowering it, and is
constructed strongly in a simple form to withstand the rough usage that such
machines generally receive, and which often proves fatal to more complicated
mechanism.
The Grab proper which may be of any form to suit the requirements of the work
is made in 2 parts each pivotted at its inner corners to a strong inner frame and its
outer corners to suspension links pivotted to the Crosshead, which slides in the inner
frame. This inner frame also carries the barrels to which are attached the lifting and
closing chains and is provided with catches for the purpose of holding back the
crosshead and so keeping the grab open until they are released by disengaging pieces
attached to the outer frame. This outer frame slides adjacent to the inner frame
being suitably guided and has retaining rods which engage with the crosshead and is
also provided with a means of suspending the grab independantly of lifting chain.
In grabs controlled by two chains this is accomplished by a chain leading away
parallel to lifting chain and in those operated by a single chain the outer frame is
provided with a headed hollow spindle or other suitable arrangement which engages
with catches suspended from some convenient structure.
These catches may
themselves be slung from this structure and operated by hand or contained in a
"block" or other convenient apparatus similarly suspended and operated either by
hand or automatically.
I will now proceed to describe the forms in which I preferably construct my
apparatus reference being had to the accompanying drawings in which the same
letters indicate the same parts:
Figs. 1. 2. 3. 4 and 5 are views of the grab in various positions. Figs. 6. 7. 8. 9. 10
and Il shew three different arrangements of the suspended block.
Fig. 1 is a front elevation and fig. 2 a side elevation of the grab shewing the
position of the catches etc. when grab is lifting the load and fig. 5 is a section
through zz figure 2.
Fig. 3 is a side elevation of grab showing the position of catches etc. when grab is
suspended from the block for the purpose of discharging its contents.
Fig. 4 is a side elevation of grab shewing the position of catches etc. when grab is
descending after having discharged its contents.

page_text: Fig. is a plan view
automatically worked catches.
SECTION VI
www
Fig. 8 is a plan view and fig. 9 a sectional elevation on y y fig. 8 of a block
shewing an alternative method of automatically working the catches.
Fig. 10 is an elevation and fig. 11 a sectional elevation of a block with catches
released by hand.
A is the inner frame of the grab constructed of angle irons. It carries the chain
barrels B. B¹ and the grab catches G and has pivotted to it at a the inner corners of
grab proper.
B is the chain barrel for the lifting chain C and B' are the chain barrels for the
closing chains C¹. They are formed together and mounted on a spindle b* which
runs in bearings b attached to the inner frame A.
C is the lifting chain leading from the crane or other machine for operating the
apparatus. It passes through the spindle and is attached to the chain barrel B.
are the closing chains each attached at one end of the barrels B' and at the other
to the crosshead at c.
D is the crosshead sliding in inner frame A. It is connected to the outer corners
of grab proper at d by means of suspension links d and to the closing chains at c. It
has holes at e through which pass freely the retaining rods E.
E are the retaining rods fixed to the outer frame at e¹ and passing freely through
guides on inner frame and through crosshead at e. They have heads e3 which
engage with crosshead D.
Fis the outer frame. It has attached to it a spindle through which passes the
lifting chain and provided with a conical head fr. It is guided by retaining rods E
and guides attached to inner frame A. When not suspended from the block H
the disengaging pieces f³ rest on the grab catches G and so support the outer
frame.
Gare the grab catches pivotted at g. to the inner frame A. They have horns g¹
which engage with the disengaging pieces f³ and projections 92 which engage with
the ends of crosshead D. They are kept in position for action by their own weight
and have pins g³ to limit their movement.
H is the block suspended from a jib head or any other convenient structure by
means of chains h¹. It is constructed hollow and coned at the bottom / so as to
easily admit the conical head fl of grab and provided with catches I.
I are the block catches pivotted at i to the block. They are of such a construction
as will easily admit the coned head f₁ of grab but will prevent its return until they
are liberated. This liberation may be effected by various methods. In figs. 10 and 11
the catches I are kept in position for action by their own weight aided by a loaded
lever J acting through link j and spindles i and released by pulling the rope j¹. In
figs. 6. 7. 8 and 9 the catches I are not rigidly attached to their spindles i but receive
motion through pins 2. They are connected by levers k to an annular weight K
which tends to keep them open. In figs. 6 and 7 these catches are put in action by
the adjustable striking pieces L fixed to inner frame of grab which come into contact
with the annular weight K. In figs. 8 and 9 they are put in action by the large
link m in lifting chain which comes into contact with the crossbar M connected to
annular weight K by rod m¹.
The method of operation of the grab with block with simple catches as shewn in
figs. 10 and 11 is as follows:-
Suppose the grab to be closed and to be being drawn up with load as shewn in
fig. 2. The conical head fl of grab passes up the block H pressing back the block
catches I. When the head passes above these catches they fall back again and so
prevent the return of the head f¹. The lifting chain C is then lowered and the
headrests on block catches. By this means the outer frame is suspended whilst
the chain barrel and inner frame A are lowered. The heads e³ of retaining rods E
come in contact with the crosshead D and keep it back the effect of this being that
the outer ends of grab proper are held back by their suspension links whilst the inner
corners descend with the inner frame thus opening the grab proper and discharging

page_text: its contents. By the time the grab is fully opened the grab catches have descended
far enough to allow the ends of crosshead to pass them and have fallen back again
into their places and the lowering of chain is stopped. The grab now hangs suspended
as shown in figure 3. On again lifting the chain the projections g² of grab
catches G engage with the crosshead D thus preventing the grab from closing so that
in this position it is lifted with the chain until the disengaging pieces f³ rest on the
horns of catches thus taking the weight off the block catches I which are, now
withdrawn by means of the hand rope j¹ so that the whole weight is again carried by
the lifting chain as shewn in fig. 4. The chain is now lowered. As long as the
weight of crosshead suspension links etc. and pull of closing chains ( act on the
ends of crosshead they cause them to grip firmly the projections g² so that although
the weight of outer frame acting through disengaging pieces f³ on horns g₁ of grab
catches tends to open them it has not sufficient power to do so until the grab proper
rests on the ground or any other sufficiently resisting medium. Then the weight of
crosshead etc. etc. is taken off the catches so that the disengaging pieces f³ acting by
the weight of frame and also the inertia acquired in descending wedge open the
catches G and then keep them open. The chain C is now lifted and as the ends of
crosshead are free the closing chain C₁ closes the grab thus filling it and when it is
closed draws the whole up and the above actions are repeated.
In some cases I work the block catches automatically. The action of the arrange-
ment shewn in figs. 6 and 7 is as follows:-
Suppose the loaded grab to be rising as before. The annular weight K keeps the
block catches open. As the conical head f¹ rises past these catches the striking
pieces L come in contact with the annular weight raising it up so that by the time
the conical head fl has passed the catches they are free to fall by their own weight
into action the striking pieces preventing the annular weight from withdrawing them.
When the chain is lowered the weight of outer frame of grab rests on these block
catches and so prevents their withdrawal by the annular weight but when the grab
again rises after having discharged its contents and the outer frame is lifted by the
disengaging pieces coming into contact with the grab catches as hereintofore
described the annular weight withdraws the catches the striking pieces L not now
being high enough to prevent this so that the grab now may be lowered as before.
In the arrangement shewn in figs. 8 and 9 the annular weight and block catches
act the same way as in figs. 6 and 7 but are put into action by means of a large link
in lifting chain instead of stop pieces on inner frame.
In some cases notably where the material operated on is of a more or less yielding
nature so that when the open grab drops on it the stoppage of motion may not be
sudden enough to release the grab catches I provide a weight fixed on the lifting
chain C of such a shape as will easily pass through the suspended block and in such a
position that when the grab rests on the material after having been quickly lowered
this weight will follow it up and strike a blow on the top of conical head f¹ thus
aiding the weight and inertia of outer frame in freeing the grab catches.
The annular weight of automatic block might be replaced by a ring of any suitable
material such as an angle iron either provided with a weight or spring. The grab
catches could also have a spring to keep them ready for action either as an aid to
their own weight or to do the whole of the work.
Having now particularly ascertained and described my invention and the manner
in which it is to be performed I wish it to be particularly understood that I do not
bind myself to the exact details described and illustrated but I do declare that what
I claim is,
1. The construction of grabs buckets or skeps with a secondary frame herein
described as the "outer "
frame having an action independently of the main or
"inner" frame which carries the grab proper and chain barrels; this secondary
frame being for the purpose of carrying the means of suspending the grab indepen-
dantly of the lifting chain, the rods or other apparatus for opening the grab, and the
disengaging pieces for releasing the catches which hold grab open.

page_text: 2. The wedge-shaped disengaging pieces for releasing the catches which hold grab
open, acting either wholly or partially by the weight of themselves and connections,
and operated substantially as shewn and described.
3. The general construction of "automatic blocks" in which the catches are
connected to a ring either weighted or provided with a spring or springs, this ring
and connections tending to keep catches open except when prevented from acting by
striking pieces on "inner
or main frame substantially as shewn and described.
33
4. The general construction of "automatic blocks in which the catches are
provided with one or more weights or springs which tend to keep catches open except
when prevented from acting by a large link or corresponding attachment to lifting
chain, acting substantially in the manner shewn and described.