Improved Grab Dredger Fittings.
Year: 1887

page_text: Date of Application, 15th July, 1887
Complete Left, 28th Mar., 1888
Complete Accepted, 27th Apr., 1888
Improved Grab Dredger Fittings.
I, JAMES RICHARD BELL, of the North Western Railway, Lahore, in the Punjab
Province of India, Civil Engineer do hereby declare the nature of this invention to
be as follows:-
This Invention relates to improved Grab Dredger Fittings which are hereinafter
described and illustrated on the accompanying three sheets of Drawing:-
:-
1. A form of my Scoop Bucket, for use in circular wells, is shown shut in
(Fig. I sheet 1) and open in (Fig. 11 Sheet 2 and Fig. III Sheet 3). It is of
partially spherical shape, flattened at the sides, and I prefer to make the sides of
the two scoops overlap each other, scissors fashion, and to turn on one spindle (A).
The Bevelled Scoop-mouths, and interstital teeth, described in the Specifications
to my Letters Patent No. 12,103 of 1884 are shewn, but plain Scoops, or Scoops
forming segments of a cylinder, may be used in conjunction with the fittings described
below.
2. The improved frame, on which I hinge the Scoops, and connect them with the
windlass is shown in (Fig. III Sheet 3) and consists of
I the Scoop Spindle (A A A A).
II the Windlass Spindle (B B) and
III the two Hangers (A B A) (ABA).
The hangers, are secured to the spindles by stout pins, passing through the joints;
the combination partaking of the nature of a lattice girder. The Scoops and the
windlass rotate on their respective Spindles, in the usual way, and I prefer to assure
any exposed spindle ends, that are liable to strike against the Well, by protecting
cupped nuts as shewn.
"
3. The two scoops of this Dredger, are opened and closed in the usual way, by
two pairs of arms, which are hinged below (by Spindles and brackets) to the Scoop
backs at (C) Figs. 1, 2 and 3 and are pivotted to each other above at (d); such
Buckets close when the apex of the arms is drawn down, and open when the apex
is upheld.
In double chain implements the apex is upheld by a second chain but in single
chain Dredgers, it is slung temporarily from a fixture, while the Bucket opens, and
the hoisting chain is then gripped, by mechanism connected to the apex.

page_text: In this invention, I place the above mentioned arms comparatively close together
see Fig. III Sheet 3, and counteract the tendency of that alternate thrust, and pull
of such arms to distort the shape of the Scoops, by two pairs of Rods (A. c. Fig. I
Sheet I) which couple the back Spindles ( . ) to the main Spindle (A).
(4.) The stops (e) which I prefer to form as prolongations of the back brackets (c)
(instead of separately attaching them to the scoop cheeks as shewn) limit and define
the angle to which the Scoops open, and the contact of the stops insures, that in
striking the ground when lowered, the Impetus of the whole apparatus is delivered to
the ground, and not Expended in over opening the Bucket.
(5.) The windlass, I use, consists as usual of two small barrels, (which act on the
Drag-chains that pull down the arms) and of a larger central sheave, to which the
end of the hoisting chain is attached.
Heretofore, a main objection to single chain Dredgers, was, that when the bucket
chanced to grasp any object that overstrained the hoisting chain, no means were
provided for releasing its grip.
The Slip Shackle depicted on the accompanying Drawing is intended to meet
such cases.
The end link of the hoisting chain see (Fig. I Sheet 1) and Fig. III
Sheet 3, is a flat plate (F) formed preferably of Steel, and is secured in either of the
slots formed in my windlass sheave, by a pin (f) made generally of a soft metal such
as copper). The pin (f) is so proportioned, that a severe strain or jerk of less
intensity than what will break the chain, will cause the plate (F) to cut or break
the pin (f) and disconnect the chain end from the windlass. The present novelty
here, consists in making the pin (f) of wood in some cases. The proportions (F)
are such that it cannot follow the chain and pass up through the chainway in the
cap (D) hereinafter described.
Consequently when severed from the Windlass and hoisted up (F) catches in the
cap, opens the Dredger and hoists it empty.
(6.) The gripper cap (D) that alternately guides and grips the hoisting chain, is
pivotted on the spindle (d) between the tops of the arms and consists essentially of:-
i A tube for guiding the Chain.
ii A detent that allows the Chain to descend, but engages with it when it
ascends, and
iii A hook or pair of hooks, for slinging the Dredger while it is being opened.
When the Dredger is slung by the hook, the latter stands erect and causes the
detent to assume its gripping position.
When the Chain is thus gripped, the detent and the poise of the tube as pivotted
keep the Hooks upright for so long as the open Dredger is hung on the Chain, and
until it lands ou the ground.
When the open Dredger lands, the Hook turns from an upright to a horizontal
position, and the detent is thereby withdrawn from action, and allows the Chain to
close the Bucket.
Where (as in the drawings) chain is used for hoisting, the tube is grooved as
shewn, for guiding the Chain, without allowing it to twist, but with a modified
section of tube and a suitable form of detent.
Rope may be employed instead of Chain.
6 A. In the form of this Cap shewn in (Figs. I, I A Sheet 1 and Fig. II A Sheet 2.) the
tube, the hooks, and the detent, are formed of one piece of metal, and see (Fig. I A
Sheet 1) the tubes back grooves, are curved to facilitate the descent of the chain.
In this case the detent is formed by the angle of the front grooves, where they return
outward as shewn, at a point between the hooks. This point is so far below the
pivot (d) that an upward stress on the chain (when gripped by the detent) keeps the
cap upturned as in (Fig. II B Sheet 2) so long as the dredger hangs on (d).
When the open Dredger lands on the ground, and upholds (d) the further lowering
of the chain's lets the whole cap turn down till the Hooks are horizontal and the
detent is then clear of the line of the chains ascent, as in (Fig. I Sheet 1).
For use with rope I make the returned groove of this variety V shaped.
6 B. In Fig. 1. B. Sheet 1 and II. B. sheet 2) the Hooks turn independently of

page_text: the tube on (d) and the detent is pivotted separately on its own spindle, in a recess
at the back of the tube.
This detent acts on the chain in virtue of the weight of its tail-piece, and is
thrown out of action when its tail is upheld. The Hooks are furnished with a tail-
cross bar, that acts on the detent as shewn, i.e. when the Dredger is slung from the
apturned Hooks, the detent is left free to act, and when once locked in the Chain
it keeps the Hooks upright.
When the Dredger lands and relieves the detent of the chain's upward stress, the
Hooks being so loaded as to fall forward, tip the detent up out of action and them-
selves assume a horizontal position. In this arrangement I prefer to attach the drag
chains from the windlass, to the Hooks, and in such fashion, that their weight and
tension draw the Hooks down, and act through them on (d) the arm top spindle.
(6 C). In cases, where it is not necessary to keep the Hooks upright while the
Dredger is being lowered, I form them in one piece with the tube, and so pivot a
detent in the side of the tube, that it falls out of action, by its own weight, as shewn
in dotted lines in (Fig. II C Sheet 2), and is caused to grip the Rising-Chain, only
when lifted by Hand to the position shewn in full line.
(6 D). Another variation of this part of my Invention, is shewn in (Figs. I D
Sheet 1 and II D Sheet 2) where the tube is so pivotted on one side of (d) and so
weighted), that when the Dredger has landed, the tubes upper end leans to the left,
while when slung by the Hooks, (which are in one piece with the tube) it leans
to the right.
In this arrangement a detent, moving on its own spindle, falls into action, when the
Hooks are upright, and falls out of action when the Dredger has landed. The detent
shewn, is made double-ended, and the lower end is for use when the upper end is
worn out.
In this arrangement I prefer to attach the drag chains to the detent Spindle.
(7.) The object of causing the Hooks of the gripper cups described above to stand
horizontal when the Dredger is shut and upright when it is open, is to facilitate
suspending the full Dredger, and lowering the empty Dredger, by the automatic
sling shewn in Figs. I, I A Sheet 1 and Fig. II A Sheet 2.
The sling (G) is a horizontal bar, and is carried by an arm that projects downwards
at a certain angle, from one side of a grooved chain tube (g) which is itself suspended
from any convenient fixture.
The hoisting chain passes through the tube, and is so guided by it, that the Hook
of the Dredger and the sling (G) are always on the same side of the Chain.
The rigidity of the Chain when under tension, tends continually to keep the
tube (g) vertical with the sling projecting to one side.
The action of this apparatus is as follows:-
-
i The hooks, lying horizontally as the Dredger rises provent a sloping surface to
the sling bar, and thereby push it out outwards, till the Hook points have risen
above (G) which thereupon engage (D).
ii When the weight of the Dredger, is then lowered on the sling, the Hooks turn
up, and the sling assumes a vertical line with the sling tube angled as in Fig. I A
Sheet 1.
iii When the Dredger has opened and the detent has engaged with the Chain, the
Dredger is slightly raised, with the Hooks standing upright, and the rigidity of the
chain then pulls the sling tube (9) vertical so that the sling (G) is disengaged from
the Hook and stands at its former angle, leaving the Dredger free to descend (see
Fig. II A Sheet 2).
7A. When the Rope is used in lieu of chain, I extend the Bar of the sling till it
forms a complete horizontal ring supported at several points from the sling tube which
I then hang in gimbols so that it may cant freely in any direction. The action of
this modification, is identical, with that of the chain sling except that the latter
acts in any one, while the Rope sling, acts in all vertical planes. This arrange-
ment is shown in the drawings.
In the Specification to my Letters Patent No. 12,103 of 1884 I have described a

page_text: mode of causing Dredgers to dig hard soils percussively, by successive downward
strokes, which strokes are induced by consecutive upward jerks, delivered by the
hoisting mechanism to the chain that closes the Dredger.
In the present invention, I deliver such jerks, by repeating. the operation, first
slackening the Chain and then swiftly tightening it by applying to any ordinary
hoisting machinery, such a measured and limited amount of power, as serves to
hoist the Chain itself, but cannot overcome the resistance offered by the Dredger.
The essential features of an automatic arrangement, by which the Chain can be
thus alternately slackened, and smartly tightened, are shewn in Fig. IV Sheet 1,
where a winch, driven by friction gearing, is pressed into gear by lever (H) and
tends continually to be pulled out of gear, by the tension of the hoisting chain.
The Dredger of the frictional grip, to be used for tightening the Chain, is
adjusted by a spring or weight (7) acting on the lever (H).
This apparatus works as follows:-
i While the chain is slack after the Dredger has just been lowered, I adjust the
grip of the friction gear, by (h) and set the motive power in action. This tightens
the chain, till it at once jerks the Dredger Windlass, and raises the lever (H) while
it pulls the friction wheel out of gear.
ii By this means, the chain both delivers its jerk and slackens itself, to an extent,
that depends on the time in which (h) (after being raised) rebounds and puts the
friction gear again in action, after that the Chain is again tightened and jerked as
before.
In some cases, I regulate and retard the rebound of (h) by an oil cataract or other
well known mechanism; suitable to checking its fall, and
extent to which the chain slackens, between the jerks. I also regulate the speed of
thereby increase the
the motor while the winch is out of gear, by a brake or other retarding mechanism
operated by the Rise of the Lever (H). The process of so jerking the chain is only
to be carried on, till the Dredger is judged to be a little more than half closed;
and, as up to that point the hoisting chain is still wrapped round the windlass Barrel, the
impetus of the jerks, (which would otherwise tend to sever the pin of the slip shackle
at the end of the chain) is only delivered to the windlass.
When, therefore, the attendant judges the Dredger to be a little more than half
shut, he increases the pressure on the Lever (H) to what will certainly lift the
Dredger, which thereupon closes and comes up.
The friction gear, above described, is in some cases used solely for jerking and the
hoisting operation is then carried out by a distinct gearing of any ordinary type.
9. In lieu of the apparatus described in the Specification to my Letters Patent
No. 12,103 of 1884 for guiding a Dredger to inside of a well curb, I, in this
Invention, use the outrigger shewn in (Figs. V, V A, and V B Sheet 3, consisting of
a pair of arms. The arms are hinged in mid length, as a two foot rule is hinged,
so that they will fold up when lifted by the middle, but will remain stiff when
upheld by the ends. The front halves of the arms are pivotted to the axis of the
Dredger, and project so far beyond it, that the extreme ends, which are furnished
with light Rollers, keep the open Dredger Scoop, from actual contact with the Well.
It is desirable, but not essential, to form the Well-shaft with vertical grooves or
guides by which the Rollers, can be led down to any particular segment of the
periphery of the Well-carb. The back ends of the arms are connected to each other
by a spindle, on which a heavy roller is mounted. The spindle of the foot-Rule
joint should have rope attached to it.
This apparatus acts as follows:-
i In descending the well-shaft, with the outrigger following the Dredger down as
in (Fig. V Sheet 3) the joint straightens itself and the weight of the back-end roller,
passes the Rollers at the front end (when the Dredger is against the opposite side as
shewn).
ii On reaching the bottom, if the length of outrigger is properly proportioned to
the splay of the Well-curb, the back roller end usually falls on the ground and
when the dredger has closed and begins to rise, the Rule joint folds as shewn in

page_text: (Fig. V A Sheet 3) and lets the Dredger come up first, with the outrigger hanging
from it as shewn at (Fig. V B Sheet 3).
The Rope which I attach to the Rule joint Spindle of the outrigger, is used, (in
cases when the arrangement accidentally sticks in the bottom of the well) for com-
pelling the joint to buckle up.
9 A. In a modification of the above outrigger, not depicted in the drawing the
front arms are cut off at the Dredger Spindle, the front Rollers are substituted by
Rubbing Pieces fixed to the scoop and the Rule joint Spindle is connected to the
apex of the Dredger arms by a short chain. This arrangement descends and doubles
up exactly as the former one does, but instead of coming up hanging at full length
below the Dredger; the Rule joint is so upheld by the short chain that the outrigger
comes up compactly folded.

page_text: I, JAMES RICHARD BELL, of the North Western Railway, Lahore, in the Punjaub
Province of India, Civil 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:-
This Invention relates to improved Grab Dredger Fittings which are hereinafter
described and illustrated on the drawings left with the Provisional Specification.
1. A form of my Scoop bucket, for use in circular wells, is shown shut in Fig. 1
Sheet 1, and open in Fig. 2 Sheet II and Fig. III Sheet 3. It is of partially
spherical shape, flattened at the sides, and I prefer to make the sides of the two scoops
overlap each other, scissors fashion, and to turn on one spindle A.
The bevelled Scoop mouths and interstital teeth described in the Specification to my
Letters Patent No. 12103 of 1884 are shewn, but plain Scoops, or scoops forming
segments of a cylinder, may be used in conjunction with the fittings described
below.
2. The improved frame on which I hinge the Scoops, and connect them with the
windlass is shown in Fig. III. Sheet 3 and consists of:-
i The Scoop Spindle (A A A A).-ii. The windlass Spindle (B B) and iii. The two
hangers (A B A) (A B A).
The Hangers, are secured to the Spindles by stout Pins, passing through the
joints; the combination partaking of the nature of a lattice girder. The Scoops and
the windlass rotate on their respective Spindles, in the usual way, and I prefer to
secure any exposed Spindle-ends, that are liable to strike against obstructions, by
protecting cupped nuts as shewn.
3. The two Scoops of this Dredger are opened and closed in the usual way, by two
pairs of arms, which are hinged below (by Spindles and brackets) to the Scoop backs
at (c) Figs. 1, 2 and 3 and are pivotted to each other above at (d). Such Buckets
close when the apex of the arms is drawn down, and open when the apex is upheld.
In double chain implements the apex is upheld (when it is intended to open the
dredger) by a second chain but in single chain Dredgers, it is slung temporarily from
a fixture until the Bucket opens, after which the hoisting chain is grasped by
mechanism connected to the apex that grips the chain while the dredger is being
lowered.
In this Invention, I place the above mentioned arms comparatively close together,
see Fig. III Sheet III and counteract the tendency of the alternate thrust and pull
of such arms to distort the shape of the Scoops, by two pairs of Rods (A. c. Fig. 1
Sheet 1) which couple the back spindles (C) to the main Spindle (A).
4. The stops (e) which I prefer to form as prolongations of the back brackets (c)
(instead of separately attaching them to the Scoop cheeks as shown) limit and define

page_text: the angle to which the Scoops open and the contact of the stops insures. that in
striking the ground when lowered, the impetus of the whole apparatus is delivered
to the ground, and not expended in over opening the bucket.
5. The windlass I use consists as usual of two small Barrels, (which act on the
Drag-chains that pull down the arms) and of a larger central sheave, to which the
end of the hoisting chain is attached.
Heretofore, a main objection to single chain Dredgers, was, that when the bucket
chanced to grasp any object that overstrained the hoisting chain, no means were
provided for releasing its grip.
The
The slip shackle depicted on the drawings is intended to meet such cases.
end link of the hoisting chain (see Fig. 1 Sheet 1 and Fig. III Sheet 3) is a flat
plate (F) formed preferably of Steel, and is secured in either of the slots formed in
my windlass sheave, by a pin (f) made generally of a soft metal such as copper.
The pin (f) is so proportioned, that a severe strain or jerk of less intensity than
what will break the chain, will cause the plate (F) to cut or break the pin (ƒ)
and disconnect the chain end from the windlass. The immediate novelty_here,
consists in making the (pin f) of wood in some cases. The proportions of (F) are
such that it cannot follow the chain and pass up through the chain way in the cap (D)
hereinafter described.
Consequently when severed from the Windlass and hoisted up (F) catches in the
cap, opens the Dredger and hoists it empty.
6. The gripper cap (D) that alternately guides and grips the hoisting chain, is
pivotted on the spindle (d) between the tops of the arms and consists essentially of:-
i. A tube for guiding the chain. ii. A detent that allows the chain to descend
but engages with it when it ascends, and iii. a hook or pair of hooks for slinging
the Dredger while it is being opened. When the Dredger is slung by the hook, the
latter stands erect and causes the detent to assume its gripping position.
When the chain is thus gripped, the detent and the poise of the tube as pivotted
keeps the hooks upright for so long as the open Dredger is hung on the chain, and
until it lands on the ground.
When the open Dredger lands, the hook falls from an upright to a horizontal
position, and the detent is thereby withdrawn from action, and allows the chain to
close the bucket.
Where (as in the drawings) chain is used for hoisting the tube is grooved as shewn,
for guiding the chain without allowing it to twist, but with a modified section of
tube and a suitable form of Detent; Rope may be employed instead of chain.
6 A. In the form of this cap shewn in Figs. I, I A Sheet 1 and Fig. II A Sheet 2 the
tube, the hooks, and the detent, are formed of one piece of metal, and (see Fig. I A
Sheet I) the tubes back grooves, are curved to facilitate the descent of the chain. In
this case the detent is formed by the angle of the front grooves, where they return
outward as shewn, at a point between the hooks; This point is so far below the
pivot (d) that an upward stress on the chain (when gripped by the detent) keeps the
cap upturned (as in Fig. II B Sheet 2) so long as the dredger hangs on (d).
When the open Dredger lands on the ground, and upholds (d) the further lowering
of the chains lets the whole cap turn down till the hooks are horizontal and the
detent is then clear of the line of the chains ascent (as in Fig. 1 Sheet 1).
For use with rope I make the returned groove of this variety V shaped.
6 B In Fig. 1B Sheet 1 and 11 B Sheet 2 the hooks turn independently of the tube
on (d) and the detent is pivotted separately on its own spindle, in a recess at the back
of the tube.
This detent acts on the chain in virtue of the weight of its tail-piece, and is thrown
out of action when its tail is upheld as in Fig. 1B Sheet I. The hooks are furnished
with a tail-cross bar, that acts on the detent as shewn, i.e. when the Dredger is slung
from the upturned hooks, the detent is left free to act and when once locked in the
chain it keeps the hooks upright for so long as the weight of the dredger keeps its
strain on the chain.
When the Dredger lands and relieves the detent of the chains upward stress, the

page_text: Hooks, being so loaded as to fall forward, tip the detent up out of action and them-
selves assume a horizontal position. In this arrangement I prefer to attach the
drag chains from the windlass, to the hooks, and in such fashion, that their
weight and strain draws the Hooks down, and act through them on (d) the arm top
spindle.
(6 C.) In cases, where it is not necessary to keep the hooks upright while the
Dredger is being lowered, I form them in one piece, with the tube, and so pivot a
detent in the side of the tube, that it falls out of action, by its own weight, as shewn
in dotted lines in Fig. II C Sheet 2, and is caused to grip the rising chain, only when
lifted by hand to the position shewn in full line.
(6D) Another variation of this part of my Invention, is shewn in Figs. I D Sheet I
and II D Sheet 2, where the tube is so pivotted on one side of (d) and so weighted,
that when the Dredger has landed, the tubes upper end leans to the left, while when
slung by the hooks, (which are in one piece with the tube) it leans to the right.
In this arrangement a detent, moving on its own spindle, falls into action, when the
hooks are upright and falls out of action when the Dredger has landed. The detent
shown, is made double ended, and the lower end is for use when the upper end
is worn out.
In this arrangement I prefer to attach the drag chains to the detent spindle.
7. The object of causing the hooks of the gripper caps described above to stand
horizontal when the Dredger is shut and upright when it is open, is to facilitate
suspending the full dredger, and lowering the empty dredger, by the automatic
sling shewn in Figs. I, I A Sheet I and Fig. II A Sheet 2.
The sling (G) is a horizontal bar, and is carried by an arm that projects downwards
at a certain angle, from one side of a grooved chain tube (9) which is itself suspended
from any convenient fixture.
The hoisting chain passes through the tube and is so guided by it that the hook of
the Dredger and the sling (G) are always on the same side of the chain. The rigidity
of the chain when under tension, tends continually to keep the tube (9) vertical with
the sling projecting to one side.
The action of this apparatus is as follows
:-
i The hooks lying horizontally as the Dredger rises, present a sloping surface to
the sling bar, and thereby push it out outwards, till the hook points have risen
above (G) which thereupon engages (D).
ii When the weight of the Dredger, is then lowered on the sling the books turn
up, and the sling assumes a vertical line with the sling tube angled as in Fig. 1 A
Sheet 1.
iii When the dredger has opened and the detent has engaged with the Chain, the
dredger is slightly raised, with the hooks standing upright, till they clear the sling
when the rigidity of the chain pulls the sling tube (9) vertical and disengages the
sling (G) from the hook, (G) then stands at its former angle, which leaves the dredger
free to descend (see Figs. II A Sheet 2).
7 A. When the rope is used in lieu of chain, I extend the har of the sling till it
forms a complete horizontal ring supported at several points from the sling tube,
which I then hang in gimbols so that it may cant freely in any direction. The action
of this modification is identical with that of the chain sling, except that the latter acts
in only one plane, while the rope sling acts in all vertical planes. This arrangement
is not shewn in the drawings but is analogous to the bell shewn in my Letters Patent,
12103 of 1884.
8. In the Specification to my Letters Patent No. 12103 of 1884 I have described a
node of causing Dredgers to dig hard soils percussively by successive downward
strokes, which strokes are induced by consecutive upward jerks, delivered by the
hoisting mechanism to the chain that closes the Dredger.
In the present invention, I deliver such jerks, by repeating the operation of first
slackening the chain and then swiftly tightening it by applying to any ordinary
hoisting machinery, such a measured and limited amount of power, as serves to hoist
the chain itself, but cannot overcome the resistance offered by the Dredger. The

page_text: essential, features of an automatic arrangement, by which the chain can be thus
alternately slackened, and.smartly, tightened, are shewn in Fig. IV Sheet 1, where a
winch, driven by friction, gearing, is pressed into gear by a lever (H) and tends
continually to be pulled out of gear; by the tension of the hoisting chain.
The extent of the frictional grip, to be used for tightening. the chain, is,adjusted by
a spring or weight (/) acting on the lever (H).
This apparatus works as follows:-
While the chain is slack after the Dredger has just been lowered; I adjust the grip
of the friction gear, by (h) and set the motive power in action. This tightens the
chain, till it at once jerks the Dredger Windlass, and raises the lever (H) while it
pulls the friction wheel out of gear.
ii. By this.means, the chain both delivers its jerk and, slackens, itself, to an extent,
that depends on the time in which (A) (after being raised) rebounds and puts the
friction gear again .in action. After that the chain is again tightened and jerked as
before.
In some cases;. I regulate. and retard the rebound of (h) by an oil cataract or other
well known mechanism, suitable to checking its fall, and I thereby increase the extent
to which the chain slackens, between the jerks. I also regulate the speed of the motor
while the winch is out of gear; by a break or other retarding mechanism operated by
the rise of the lever (H). The process of so jerking the chain is.only to be carried
on, till the dredger is judged to be a little more than half closed; and, as up to that
point the hoisting chain is still wrapped round: the Windlass Barrel, the impetus of
the jerks, (which would otherwise tend to sever the pin of the slip shackle at the end
of the chain) is only delivered, to the windlass..
When, therefore, the attendant judges the Dredger to be a little more than half shut,
he increases the pressure on. the lever. (H), to what, will, certainly, lift. the Dredger,
which thereupon closes and comes up.
The friction gear above described, is in some cases used solely for jerking and the
boisting operation is. then carried out by a distinct gearing of any ordinary type.
9. In lieu of the apparatus described in the Specification to my Letters Patent
No. 12103 of 1884. for guiding a.dredger to the inside edge of a well curb, I, in this
invention, use the outrigger shewn in Figs. V, V. A, and VB Sheet 3, consisting of
a pair of arms. The arms are, hinged in mid length, as a two foot rule is hinged, so
that they will fold up when lifted by the middle, but will remain stiff when upheld
by the ends. The front halves of the arms are pivotted to the axis of the Dredger,
and project so far beyond it that the extreme ends, which are furnished with light
Rollers, keep the open Dredger Scoop, from actual contact with the Well. It is
desirable, but not essential, to form the well shaft with vertical grooves or guides by
which the rollers can be led down to any particular segment of the periphery of the
well curb and in this matter I-prefer to use well shafts polygonal in plan-by whose
angles the lode cutting dredger may be guided. The back ends of the arms are
connected to each other by a spindle, on which a heavy roller is mounted. The
spindle of the foot-rule joint should have rope attached to it.
This apparatus acts as follows:-
i In descending the well-shaft, with the outrigger following the Dredger down as
in Fig. V Sheet 3 the joint straightens itself and the weight of the back-end Roller
presses the rollers at the front end (where the Dredger is against the opposite side as
shewn).
ii On reaching the bottom, if the length of outrigger is properly proportioned to
the splay of the well-curb, the back roller end usually falls on the ground and when
the dredger has closed and begins to rise, the rule joint folds as shown in Fig. VA
Sheet 3 and lets the dredger come up first, with the outrigger hanging from it as
shewn at Fig. V B Sheet 3.
The rope which I attach to the rule joint spindle of the outrigger, is used, (in cases
when the arrangement accidentally sticks in the bottom of the well) for compelling
the joint to buckle up.
9 A In a modification of the above outrigger, not depicted in the drawing the front
B

page_text: arms are cut off at the Dredger Spindle the front rollers are substituted by rubbing
pieces fixed to the scoop and the rule joint spindle is connected to the apex of the
Dredger arms by a short chain. This arrangement descends and doubles up exactly
as the former one does ; but instead of coming up hanging at full length below the
Dredger the rule joint is so upheld by the short chain that the outrigger comes up
compactly folded.
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 :-
In a Grab Dredger :-
1. A frame consisting of a scoop spindle, a windlass spindle and hangers, constructed,
combined and arranged to operate substantially as described.
2. A slip-shackle (secured to the windlass by a light pin made preferably of wood
or copper) so proportioned that the shackle cannot pass up through the chain-way in
the cap but will catch therein and open the dredger should the pin be severed,
as it must be under any tension that restrains the hoisting chain, substantially as
described.
3. A gripper cap consisting of a guiding tube, a detent, and hook or hooks,
combined and arranged to operate substantially as described.
4. A detent arranged to pivot separately on its own spindle, to act on the chain by 2
the weight of its tail piece and to be thrown out of action when the tail is upheld,
substantially as described.
5. The modification of this detent as described and shewn Figs. ID Sheet 1 and
II D sheet II of the drawings.
6. A sling consisting of a horizontal bar carried by an arm projecting downwards 2
from a suspended grooved chain tube, constructed and combined substantially as
described.
7. The automatic arrangement for alternately slackening and tightening the chain
substantially as described.
8. An outrigger for guiding the dredger substantially as hereinbefore described and 3
shewn Figs. V, VA and VB Sheet 3 of the drawings.
9. The modification of said outrigger substantially as described.
Dated this Twenty eighth day of March 1888.