IMPROVEMENTS IN SELF ACTING EXCAVATORS, ELEVATORS OR SKIPS, AND THEIR AUXILIARY CONTRIVANCES
Year: 1884

page_text: I, JAMES RICHARD BELL, of 113 Canning Street, Liverpool, in the County of
Lancaster, Civil Engineer do hereby declare the nature of my invention for
"IMPROVEMENTS IN SELF ACTING EXCAVATORS, ELEVATORS OR SKIPS, AND THEIR
AUXILIARY CONTRIVANCES" to be as follows:-
My Invention relates to improvements in Self Acting Excavators, Elevators or
Skips and their auxiliary contrivances, applicable to Dredging, to digging, lifting
or lowering and discharging in bulk any soil, mineral product or produce that is
capable of being dug, and to undersinking cylinders, wells, or other foundations.
This Invention has reference to apparatus in which a Bucket formed of two
scoops digs when it is closed by a windlass acting on the rigging of the Bucket and
discharges when opened by a suspending hook.
The auxiliary appliances are:-
(a) A modification of hoisting engines to cause excavator scoops to close by jerks
or stabs in lieu of by continuous motion.
(b) Sundry appliances for guiding such Implements to desired positions both for
discharging and for excavating.
1 The Bucket of the Excavator consists of Two Pans or Spades, hinged by
their sides to and turning, in closing, towards each other on the Bucket Spindle, or
Spindles.
1
The sharpened cutting faces of the pans meet when closed along one straight line
without overlap. In short the Bucket closely resembles that of the well known
"Bull's" Dredger with the special exception, that a cross section of. the Bucket
drawn at right angles to the Spindle, instead of being wholly curved so that the
cutting edges of the pans meet circumferentially, has the shape of an inverted.
pointed arch, so that the lines of the cutting edges when produced intersect at an
angle as tangents to an arc of a circle.
la To the outsides of the spades, teeth or prongs are so fastened as to project
beyond the cutting edges in the lines of the tangents above referred to. And in
virtue of the angle at which the cutting edges meet each other the teeth of one
spade diverge from the back of the opposite spade at an angle preferably for general
work of about 30 degrees.

page_text: In the length of the face of each spade the teeth are at such intervals as allow
the teeth of one set to pass to one side of those of the opposite set.
The four teeth adjacent to the four corners of the two spades are preferably made
longer than the intermediate teeth in order that the first attack in digging very
hard material may be concentrated on a limited number of points.
2 The Rigging of the Excavator consists of two quasi triangular side frames
each as wide at bottom as and there hinged to the back corners of each spade; and
of a comparatively narrow head-block to which the narrow tops of the side frames
are hinged.
The solid figure defined by the head-block and the two tapering frames is
therefore that of a truncated pyramid superposed on the Bucket, and this form
facilitates working the Excavator in confined spaces and when ascending tends to
clear the shoulders of a well or the combings of a batch way automatically.
3, The open Excavator is closed in this Invention by a Jack or windlass that
draws the head-block down and thrusts the spades (through the intervention of
the side frames) downwards and in course of rotation on the Bucket Spindle
together.
Hereinafter I term the rope or chain that lifts the Excavator the Rope or
hoisting rope and that or those which pull down the head block to the Jack the
Chain or Jack Chain.
30, For closing this Excavator I generally use a Disk Windlass or a pair of such,
The disk is generally but not necessarily circular and has, in the line of its
(greater if it have a greater) diameter, a line of holes or eyes pierced through it,
in either of which the spindle on which it is to work may be inserted. One hole
is in the centre of the diameter and the others at convenient distances along one
half of the diameter but none on the other half. As a rule the harder the
material to be operated upon the more eccentric should be the spindle of the
Disk-Windlass.
The edge of the Disk is grooved to suit a rope or chain which is itself fastened
to the periphery, at a point found by drawing a perpendicular to the diameter in
which the Spindle holes lie, at a point midway between the centre hole and that
most excentrically placed, Between its attachment to the Disk and its end con-
nected to the Head-Block this rope or chain forms the Jack-Chain. The other end
is attached to and forms a prolongation of the hoisting rope.
When the Excavator is full open the Jack-Chain stretches tightly from the
head-block to the point of its attachment which then lies directly over the Windlass
Spindle.
Beyond the attachment to the Disk the hoisting rope passes down the side of the
Disk near the eccentric boles and onward underneath and round the Disk till it
leaves it to pass upward through the head-block to the hoisting engine.
In fact when the Dredger is open and the Windlass arranged on an eccentric axis
the hoisting rope enwraps the lower circumference under the longer arm and the
Jack-chain joins the shorter arm directly to the head-block. The circumference of
the Disk is such that about half a rotation takes up as much closing chain as will
shut the Excavator.
By changing the Windlass Spindle from hole to hole various ratios of initial
leverage can be applied, In all cases the greater the initial leverage the less is the
final leverage and the apparatus can thus bo adapted within its limits to a variety
of circumstances and materials. And yet the amount of hoisting work required to
shut the Excavator is practically constant for all cases.
3b. The axes or common axis of the Disks are placed at right angles to the
Bucket Spindle and work in eyes in a pair of stout flitch plates to which the bucket
spindle is firmly attached.
Where two disks are used the Two Jack-Chains are either continuous in one
piece and pass over a loose pulley in the head-block or their upper ends are shackled
to a compensating lever, either of which plans allow the relative lengths of the
Jack Chains to adjust themselves automatically.

page_text: 3c, I may either use the above described Disk Windlass or a circular Windlass
having a large barrel for the hoisting rope and a small barrel for the Jack-Chain
and with or without the above flitch plate connection to the Bucket Spindle.
4. The fact of the Bucket closing stops the further rotation of the above as of
any other forms of Jacks and a continued strain on the hoisting rope then lifts tho
Excavator and its load.
To open the bucket, discharge the contents and reset the Excavator for a new
operation I use a mechanism which I terin a Dog and Bell.
:
4, The Dog consists of a stout shank hinged at its foot to the head-block of the
Excavator & formed at its head into a back hook and a forehook acting in the
direction of the motion of the Dog on its hinge. Aided by a spring the weight of
the Dog head causes the Dog to overhang backwards leaning from the hoisting rope
which passes vertically through or near the centre of the head-block.
4b, The Bell is a stout ring having its under surface shaped as the frustum of a
hollow cone. Its outer and lower part is connected to suspending rods which allow
it to swing freely in any direction through a small arc.
The hoisting rope passes up through the Bell and is kept at or near the centre
of the cone by a guide ring fixed to the rods in the axis of the cone prolonged,
The upper edge of the Bell free of any obstruction is so shaped all round, as to
engage the back hook of the Dog at any point of its circumference at which
(owing to the hoisting rope or chain twisting) the Dog may happen to arrive.
4c. When the Dog leaning backwards is hoisted with the Excavator into and
through the Bell it pushes the Bell over till the back hook clears the Bell's upper
edge, and when thereafter the Excavator is lowered the Bell edge having swung
back underhangs the back hook, engages with it and thereby takes the weight of
the Excavator through the Dog and head-block.
As lowering is continued the point from which the Bell hangs, the Bell edge,
Dog Spindle, and Bucket Spindle fall into one vertical line and ultimately the
strain on the Windlass, which kept the Bucket closed being released the bucket
spindle descends, the Bucket opens and discharges its contents and the windlass
rotates backwards till the whole Excavator comes automatically into the open
position.
4d In allowing the Excavator to open as above described, while the Back-Dog-
Hook hangs on the Bell the fore hook leans forwards and the hoisting rope in
slackening passes over the Dog's fore hook and is pressed against that hook and at
the same time prevented from getting to either side of it by a guard or Fence
which is pushed against the fore hook by a spring.
I prefer to make the fore hook in the form of a double claw of such proportions
that though it will not engage in the plain links of a chain it will take upon the
shoulders of a shackle of ordinary construction which with its open end up takes
hold of a specially long link that forms the lower end of the rope.
From the shackle downwards to the windlass the rope is substituted by chain
and as this works over guide sheaves the shackle cannot twist but is maintained
in the position in which the hook and shackle can engage.
In opening by its own weight, the Excavator overhauls this chain portion of the
hoisting rope till the shackle is below the hook and thus when the engine again
hoists the rope the shackle engages the front hook and so suspends the Dredger in
its open position that the back hook is kept so nearly upright that it will not now
catch the side of the Bell.
4, Where two windlasses are used the hook engages a ring which connects the
two windlasses or Jack Chains to the rope, or a plain rope may be used throughout
and the hook then engages the edge of a cup-shaped ring fixed on the rope, or
instead of the shackle a Ball may be fixed on the chain or on the wire rope; or
again, the fore hook may be substituted by a nipper which grips the rope when
thrown in gear and releases it when out of gear. This nipper will act only against-
the closing and not against the opening of the Excavator, and will be put in and
out of gear by the movements of the back hook.

page_text: 4, When the Excavator has been lowered on to the material to be excavated its
weight is relieved from the Dog or nipper which is then drawn back by its spring
and leaves the hoisting rope free to act on the windlass and close the bucket
de-novo.
4 The point from which the Bell is ultimately suspended should plumb the
place where the load is to be discharged and need not necessarily be in the line on
which the Excavator is hoisted.
If out of that line the loaded Excavator once hooked to the Bell swings out in
lowering till the Bell plumbs its suspension before discharging. In this arrangement
the empty Bell requires to be drawn sideways to the line of the hoisting rope by
a light counterpoise and chain.
4b, When a loaded skip or Elevator has to be hoisted over an obstacle and then
lowered before discharging, the Bell is hung by a sufficiently long chain and is first
carried up on the shoulders of the Head-Block and again lowered till the length of
its chain reached, after which the Bell catches the back hook and empties the
bucket as before. The empty Excavator on being hoisted over the obstacle again,
carries the Bell within the length of the Bell chain on the shoulders of the Head-
Block.
5. For digging materials of a hardness beyond the power of the largest con-
venient ratio of windlass-leverage I have recourse to percussion for advancing the
teeth or cutting edges of an Excavator by a consecutive series of short stabs or
blows, much as a labourer stamps a spade into hard clay.
I may attain this object either by hoisting slowly over a rocking pulley or by
giving the rope a reciprocating action to drive an intermittent Hydraulic Pulling-
Jack.
5*, The rocking pulley is a loose sheave carried by a pair of arms that are
caused to rock by any convenient reciprocating action. According to the relative
disposition of the hoisting barrel and any leading pullies that may guide the rope
to its work, the rope may pass over or under the rocking pulley so long as the
fore stroke of the pulley tightens and its back stroke slackens the rope.
The most convenient and suitable motion for the pulley arms is one akin to that
of a tilt hammer, when the positive motion equivalent to raising a tilt hammer
given by any convenient rotary cam or reciprocating motion causes the back stroke
of the pulley, while the free fall of a weight accelerated and regulated by an
adjustable spring delivers a pull to the rope through the rocking pulley.
In using this device the rope when lowering the Excavator, is given a consider-
able amount of slack after the Excavator has reached the bottom to be acted upon.
The rocking pulley is then set to work, and coincidently the rope is wound very
slowly upward and consequently, after, it may be, a few ineffective strokes the
fore stroke of the pulley at the end of its course so tightens up the rope as to
deliver a jerk to the Jack or windlass that closes the Excavator and thence
necessarily to the cutting edges or teeth.
If the tension given to the tilt spring be too great it will result in each Jack
lifting the Excavator as well as driving its teeth and in that case the Excavator
will when hoisted come up more or less empty, as it has been partly made to dig
and partly to scrape itself shut.
This contingency is provided against in the next operation, by the operator
adjusting the tension of the spring.
5b, If again the proper spring tension results in the resistance offered to the
teeth stopping the fore stroke of the rocking pulley before it is fully accomplished,
it is obvious that the alow hoisting action of the barrel is taking up more chain
than the advance of the Excavator cutters warrants, and the operator must then
reduce or even stop the hoisting action till the rocking pulley attains once more its
full stroke, or very nearly so.
To do this demands a variable winding feed and the device I use for that purpose
consists in an adaptation of the common and well known ship's band windlass in
which the barrel-shaft is keyed to a friction wheel driven by a friction clutch

page_text: netunted through a link by a rocking lever. In this Invention the lever is an
extension or connection of. the arms that carry the rocking pulley; the upward
stroke of the clutch drives the barrel, and the link between the lever and the
friction clutch is either a chain or so hinged or slotted as that it always draws the
friction clutch up to the top of its upstroke but only permits, without compelling,
the fall of the clutch to the extent of the down stroke. The down stroke of the
clutch is separately effected by a weight or spring and an adjustable stop allow
the operator to altogether prevent the descent of the clutch below the top point
of the lever's stroke or to regulate it within the limits allowed by the link.
Recoil of the hoisting barrel is prevented in any ordinary manner, and as the
degree to which the rope is hoisted is relative to the extent of the upstroko of tho
clutch the adjustment of the stop will cause the amount pulled in at each stroke to
vary from nil to its maximum.
50 Where very light jerks are required the variablo feed may be employed
without the intervention of the rocking pulley to surge the hoisting rope, which is
in that case kept practically taut throughout the operation, suitable arrangements
of well known kinds are used for either disconnecting the pulley rocking gear
from the friction-clutch-lever or both from the hoisting engine which is then free to
raise the Excavator in any usual and convenient manner.
5d The hydraulic pulling Jack is a substitute for the Disk or other windlass and
Jack chains of an Excavator and consists of a tube or cylinder closed at one end
and containing a piston whose rod passes out of the other end through a Stuffing
Box. When the Excavator is open the piston Rod is out to its full extent and the
back end of the cylinder contains the water and also a considerable air-space.
When more convenient the air-space may be a distinct vessel. A single acting
pump is arranged to draw water from the back.und force it into the front end of
the cylinder through suitable passages furnished with valves to prevent reflux.
It is a neat and convenient arrangement to fix the pump at the end of and to
form the passages in the piston rod, just as in "Tangyes" hydraulic pulling Jacks.
The pump, which as before said is single-acting draws water from the back end of
the cylinder during the down stroke, which is actuated by a spring and forces that
water into the front end by its upstroke which is effected by the hoisting rope.
The elasticity of the air in the air vessel connected to the back end of the cylinder
allows the water to be freely withdrawn at each down stroke and the piston to
advance at each upstroke. A suitable cock is provided for replenishing the air.
The piston rod is linked in this Excavator to the Bitch plates and the back end of
cylinder to the head-block and may be similarly coupled to the rigging of other
Excavators and Dredgers.
A suitable cock connects the passages from the back and fore ends of the
cylinder; this cock is closed by a spring and opens when a weight attached to the
hoisting rope is lowered down till it presses down the cock-lever.
5, The intermittent Jack is operated as before said by the hoisting rope being
worked up and down by the rocking pulley, the hoisting rope in this arrangement
is tightened as required by the variable feed described above in paragraphs 5º
and 5b. After lowering the Excavator the rocking pulley is set in motion and the
rope tightened by the feed till it is perceived that the range of the pump ram
prevents the rocking pulley from quite attaining its full forestroke. After this the
rope must not be any further tightened till the Excavator is ready to ascend.
In this condition each upward jerk delivers a pump-full of water with much
momentum under the piston, but when the Excavator's teeth meet and the piston
can no longer rise the pump ram keeps the rope down and the attendant perceiving
that the rocking pulley is kept down throws the jerking apparatus out of gear and
winds up the Excavator as usual.
When Dogged on the Bell and the rope lowered the Excavator opens auto-
matically by a weight attached to the rope falling on the lever of the discharge
cock which closes again of itself when the weight, is raised,
If the weight

page_text: accidentally opens the discharge cock while the bucket is open it is of no
consequence as there is no pressure to produce reflux of the water.
6. Í have previously described (see paragraphs 4f and 4s) my method of guiding
this apparatus to a desired point for discharging its contents, and I will now
proceed to describe my method of guiding the Excavator to any point of attack
which cannot be reached by lowering it vertically.
The
For this purpose the Excavator is furnished with a detachable outrigger forming
a triangle, of which the flitch plates and bucket spindle form the base.
outrigger is the hypothenuse and the upright is a vertical spindle. The outrigger
end at top and the bucket spindle at bottom of this triangle each carry a projection
that serves at once as a fixed clip to embrace one side of a rail head, and as an eye
in which the vertical spindle turns. The spindle carries at top and bottom a
.projection to clip the other side of the rail so that when the clips are closed on a
rail head the Dredger must descend and be guided by the rail to whatever point
the rail reaches. In, for example, well-foundations a sufficient number of rails are
fixed at proper intervals round the inside of the well to guide the Excavator
successively to all parts of the ground under the wall of the well. The central
part of the area of such a well can of course be excavated by simply lowering the
Excavator vertically.
The spindle is made spiral in the middle of its length and a nut carried by a
lever hinged to the outrigger-arm in descending by its weight, or pulled by a
spring, rotates the spindle to close the rail clips.
The back end of the nut lever projects into such a position that the head-block
in descending and closing the Excavator depresses the lever, raises the nut, releases
the grip of the clips on the rail and so allows the Excavator to ascend free of the
guide rail.

page_text: COMPLETE SPECIFICATION.
I JAMES RICHARD BELI. of 113 Cauning Street Liverpool in the County of
Lancaster Civil Engineer do hereby declare the nature of my invention for
IMPROVEMENTS IN SELF ACTING EXCAVATORS, ELEVATORS, OR SKIPS AND THEIR
AUXILIARY CONTRIVANCES 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 Self Acting Excavators Elevators or
Skips and their auxiliary contrivances for Dredging Digging, Lifting, Lowering
and Discharging Soil, Mineral products, produce, and any other things, of a kind
that can be dug, and to undersinking Cylinders, Wells, and other Foundations.
Apparatus of the class to which my Invention refers-now commonly known in
England as Grab Buckets or Grabs, and in America as Clam Shell Dredgers-have
two scoops (with either plain or toothed Cutting edges) so hinged to each other
and to a frame that they dig and close against each other so as to form a bucket
when their Rigging is drawn down toward the Frame and open so as to discharge
their contents when the Rigging is upheld and the downward tension released-In
what follows I prefer to speak of the implement comprehensively as a Grab.
My auxiliary contrivances are
(a) A modification of the continuous winding action by which grabs aro
ordinarily closed, whereby I cause the scoops to dig percussively by successive
intermittent Jerks, or Stabs and :—
(b) Sundry modes of Guiding Grabs to desired positions for excavating and for
discharging.
In the accompanying drawing each Figure bears the same Roman Numeral that
marks the clause of this Specification that it elucidates.
Italic Numerals refer throughout the various Figures and paragraphs to the
same distinct thing or item of mechanism.
I My Grab Bucket (Fig 1) consists as usual of two scoops binged (at I) to each
other and to a frame.
The distinctive feature of my scoops is that they have plain cutting edges and
also teeth or picks, and can therefore pierce refractory strata when met with by
their teeth and can also shut closely upon semi fluid contents.
I effect this combination by making the plain cutting edges meet (in the closed
Bucket) at an obtuse angle as shewn and by fixing teeth on the outsides of the
Cutter plates projecting beyond the plain cutting edges of their own scoop, and
passing in the closing Bucket clear of and diverging from, the opposite scoop as
shewn at 2. and 2 a.
The teeth 2-2-2-of one scoop-occupy intervals that alternate with those
occupied by 2 a 2 a-the teeth of the other scoop. -
The scoop ends meet like the scoop faces, at an obtuse angle and carry similarly
interspaced over-lapping teeth which are indicated in the figure by dotted lines.
II The Rigging of this as of other grabs consists as shewn in Fig II of two side
frames or pairs of bars hinged (as at 3) to each scoop-back below, and to the
gudgeons of a cross head (as at 4) above.
The crosshead as usual slides on and steadies the vertical part of the Frame of
the Grab while being drawn down by Jack chains to a windlass that turns in the
lower part of the frame.
-

page_text: •
As in other Grabs, when the Crosshead is upheld and the tension exercised by
the windlass released or counteracted, the cross head through the side frames
upholds the scoop-backs while the scoop spindle and frame descends and the bucket
assumes the open position.
So long thereafter as the crosshead is upheld either absolutely in space or
relatively to the Frame the Grab remains open.
The distinctive features of my Grab Rigging and Grab frame are as follows.
I form my side frames either converging upwards and narrow (as viewed in
elevation in Fig II) above, or preferably for simplicity's sake as the narrow
parallelogram shewn in full line extending from the scoop brackets 3-3 to the
crosshead Gudgeons 4-4 but furnished when parallel with the removable Fender
Frames 9-9-9-9 which I attach for use in guiding the ascending Grab when it
works in confined situations where it is liable to have its ascent impeded.
My crosshead between its gudgeons at 4-4 divides on plan into two connected
cheekplates which are pierced at 5 for a guide sheave spindle, and at 6 for two
gudgeons or shackle pins, to which whether directly or indirectly, I connect the
Jack chains through which the Windlass delivers its down-haul.
My frame consists of a horizontal member and an upright member.
The former consists of two similar flitch plates which are connected at their ends
and formed (at 1-1) into brackets that carry the scoop spindles. In the centre of
their length the flitch plates are pierced for 7 the Windlass spindle, and at 8-8
they are stiffened by cross bars which serve also to retain the Windlass chains in
place.
In some cases I connect the stays 8-8 with each other and with the sides
(extended) of the flitch plates as at 8 a to form a semi-circular casing or well in
which the Windlass and its chains work protected from dirt.
The upright part of the frame after it has bridged the space required by the
windlass takes the form of a channel iron, which passes upwards between the
cheeks of the Cross head.
The internal dimensions of the channel are such as to conveniently contain and
guide the hoisting chain.
The triangular outrigger Frame shewn in dotted line on the right hand side of
Fig II is an auxillary appliance for guiding the descent of the grab (in for example
a well foundation) along an ordinary Rail. The ends of the outrigger at 10
and 10 a are formed (as shewn in small sectional plan) as clips to loosely embrace
the Rail head when they are drawn together by the left and right handed coupling
screws shewn. These screws are operated by the attendants overturning (to the
right) the cam pieces of which the screws form the axes. When so clipped to the
rail the grab descends freely and trails the Cams-but when the Grab begins to
rise under the action of the Hoisting Chain the excentricities of the Cams jam on
the rail, and also tighten the clips so that the grab is held down till it is nearly
closed, when a pair of links
connected to any convenient descending
point of the Rigging pulls the top cain backwards and also, through the medium
of a slotted bar, reverts the lower cam. The reversion of the cams unscrews the
couplings, opens the clips, and leaves the grab entirely free from the guide Rail by
the time it is closed and ready to be hoisted up.
III The windlass consisting of a single excentric Disk described in paragraph 34
of my provisional Specification is I find unnecessarily cumbrous and I prefer that
mentioned in paragraph 3° of the same and now illustrated in Fig III consisting of
a large middle barrel and two side sheaves.
The Middle sheave is preferably circular and has the hoisting rope or chain
(shewn thus
in all the Figures) so shackled to the Barrel as to
·
enwrap it by one whole turn when the grab
open.
.
The excentric side barrels have a small pitch radius-which is in the example
illustrated about half the pitch radius of the Hoisting Chain barrel for the first
half revolution that begins the act of closing the Grab

page_text: Towards the end of the Grab closing, the side sheave's pitch radius increases
excentrically till in the drawing it becomes about equal to the Hoisting Chain's
pitch radius.
thus
In all cases, with whatever ratios of pitch radii-I prefer to close the Grab
by a little less than one rotation of the Windlass-so that in the closed grab
the jack chains shackled to the side sheaves enwrap them as shewn by a line
The dotted shading on the right of Fig III shows the
mode by which I prefer to ballast a grab (in cases where abnormal weight is
needed) by hanging blocks on the end of 7 the Windlass spindle. The object
I seek in using my excentric Windlass is to exercise a greater purchase while
piercing the strata and a less when merely closing the Grab under the excavated
mass.
IV. For opening and lowering my Grab the common plan of using a second
chain can of course be used by shackling the second chain to the Crosshead at 6,
but in all cases where the operating of a second Chain is inconvenient for example
at great depths, or in a current that might twirl the Grab and entwine the two
chains, I prefer to open and set the Grab by means of the Bell and Dog shewn
(with variations in the Dog and its hanger) in Fig IV.
The Bell is a hollow frustrum of a Cone suspended (see Fig II) with its axis in
the line of the hoisting chain, its top edge 11 free all round and the wholo Bell
capable of swinging-as shewn in Fig II.
The Bell hangers embrace and guide the Hoisting Cbain
The Dog is a pair of shanks hinged to the Crosshead and formed above into a
broad hook behind, and into a pair of claws in front.
In the most simple arrangement which is shewn in the left hand view of Fig IV
the Dog is connected to the Cross head by internal Gudgeon's at 6, and its shanks
are formed with Tails, to which the Jack chains
are so
shackled, that the closing tension of the chains, draws the Dog (which forms in
effect a link in the Jack chains) into the dotted position shewn, that is to say
lenning backwards from the Hoisting chain. So leaning back (while being hoisted
when the Grab is shut) the Hook encounters the inner slope of the swinging Bell
as shown and pushes its edge 11 to a position such as 11 a. Thereafter when the
Hook rises and clears it, the edge of the bell swings back automatically to the
normal as at 11 b, ready for the Hook when lowered to engage it as shewn.
When by further lowering of the Hoisting chain the Windlass tension is
relaxed the weight of the Grab comes through 6 and through the Dog hook on 11,
the Bucket opens, the frame and stem descend-the contents discharge themselves,
and 6 tends to hang directly plumb under 11 as shewn at 11 c, till the book is
prevented from quite upending by a stop formed at the side of the Dog shank,
landing on the Crosshead as shown in shaded dotted line at 12.
In this position the Dog's fore claws are ready to engage 13, the Dog Hanger, a
Cross Bar connected to the top of the Stem-piece or upright frame which guides
and fences the Chain.
In the left hand view of Fig IV the stem piece is hinged at 7 so that it can move
to the left to let 13, its fixed banger, pass over the claws of the Dog.
When in this arrangement the Hanger is clear of, and below the claws, a pro-
jection from the stem piece strikes 5, the guide sheave's spindle, and pushes the
stem and its hanger under the claws with which on the hoisting chain being
tightened it becomes engaged.
Instead of hinging the stem piece at 7, I in some cases fix it and then hinge the
hanger as shewn at 13a in the middle view of Fig IV so that it clears the Dog's
claws by lifting latch fashion.
IV A In the modification shown in the right hand view of Fig IV the Hook
which is drawn back by a spring is hinged to the Cross head at 5 and is independent
of the Jack Chains and their shackles at 6.
In this arrangement the channel of the Stem (grooved
twisting) faces and is entered by the Dog's Fore Claws.
to keep the chain from
The Dog hook engages

page_text: the Bell and upends itself as before, and thus the claws are pressed against the
Chain while the stem which is hinged at 7, pushes in virtue of a spring's action
the Chain against the claws.
The Claws are furnished with inward projections shaded and marked 136 that
though incapable of catching the ordinary links of the Chain can and do engage
with a shackle interpoloted as shewn in the Chain at the point which lies under
the claws when the Grab is fully open.
In this method which is that referred to in paragraph 4d of my provisional
specification, the Chain, when hoisted upholds the cross head directly. The method
is as a rule less certain in its action (which depends largeley on the use of springs
and chain guides) than that in which the claws engage the hanger or stem head.
Whether the crosshead be upheld to the stem head as in the left and middle
figures or to the Chain as in the right band figures, it keeps the grab open while
being lowered till the scoop teeth are upborne by the Ground. When this has
taken place the scoop-backs through the Rigging, uphold the Dog, but the Chain
and shackle in one case, and the stem and hanger in the other continue to descend
through a space sufficient to disengage them from the Dog's claws, and the Dog
then falls back and allows a fresh closing operation to be effected.
V. My object in driving scoops by percussion is to substitute for the continuous
slow pushing action now used-ope akin to that by which manual or rather pedal
labor stamps a spade into the soil and I find it preferable to effect this by com-
municating blows from a steam or other power driven Hammer to the digging
implement.
Such impulses may be communicated downwardly by a Hammer directly fixed
to the Grab's Crosshead or from above through a spar to which the crosshead is
connected, or may (to implements of the class described in this Specification) be
communicated upwardly from above through the Hoisting Chain. The Chain may
receive such impulses from a clamp or gripper but preferably from a rocking pulley,
or Jerking Sheave, on whose periphery it bears.
Where the Chain passes under the Jerking sheave the Hammer acts directly
downward on the sheave's axis and where (as vido Fig V) the Chain runs over
the sheave the Hammer's downward blows are delivered to the back end of a
Rocking lever, whose fore end carries the sheave and jerks it upwardly.
Where live steam is availiable I prefer to use a Steam Hammer of any usual
construction and whether with a steam or any other power Hammer I so arrange
that the downward impetus of its moving parts are delivered to its standing parts
through springs, or preferably through a cushion of steam or air, or in some cases
of India Rubber and that the standing part of the Hammer's mechanism com-
municates that impetus, as directly as may be, and through parts that possess as
little inertia of their own as may be, to the cutting parts of the implement. The
weight and stroke of the Hammer (where the stroke can conveniently be adjusted),
are proportioned to the nature of the work, and the weight of the moving parts of
the Hammer, is, when need be, supplemented by so much fixed dead weight that
the aggregate weight though insufficient to effect the Grab, shall fully suffice to
keep the hoisting chain tight between the Grab, and the Jerking sheave. In the
example illustrated a Hammer Bar carrying a head of adjustable weight cushioned
by Rubber Springs is guided by its trunnions (14) between horn plate projections
from the back end of a pair of Rocking levers which carries a pully whose crank
pin drives the Hammer Bar.
The Hammer Pulley is rotated through a belt or pitch Chain, or other gearing
by a Driving Pulley which runs (at 15) on the Axis that pivots the Rocking
Levers, and thus in every position of the levers the two pulleys are constantly in
gear.
The fore end of the levers carries the Jerking sheave over which the Hoisting
Chain passes. The lower limit of the Sheave's movement is defined by a stop (16)
that supports the Sheave when ordinary hoisting operations are in progress. At
such times the Rocking levers can be locked up by a catch (17).. When a Grab has

page_text: been lowered, and is ready for closing, the operator unlocks 17 and winds in so
much slack chain as will draw down the Jerking sheave till it approaches, but does
not bear upon the stop (16), before starting the Hammer to work. As the jerks
raise the sheave it may be again drawn down by the Winding barrel as before, and
when the Grab is judged to be sufficiently closed it should be wound up in the
ordinary manner with the Hammer stopped and the catch (17) locked.
The above described Jerking Gear is a developement of and differs from that
described in my Provisional Specification in so much as I now prefer not to lower
the Jerking Sheave between the blows of the Hammer beyond the extent necessarily
caused by its reaction against the chain, and I now use the Counterpoising effect
of the Hammer and its adjuncts for taking in the slack of the chain, and am
enabled to dispense with the variable winding feed gear.
VI In paragraph II of the above I have already described my provisions for
guiding the descent of my grab by a fixed rail and the fenders by which I guard
its ascent in sundry situations, and it only remains to describe the arrangements
shown in Fig VI. for hoisting in one vertical line and discharging in another.
To this end, instead of hanging the bell as a fixture in the hoisting line I suspend
it there partly by chains attached to a point somewhat beyond the desired discharging
point and partly by a counterpoise and rope that suffices to keep the empty bell in
the hoisting line, but yields to the superior weight of the bell and grab when (the
dog being engaged on the bell) the grab is lowered.
Under these dispositions the full grab and bell swing out as shewn till the bell
hangs nearly under its ultimate point of support and in that position the tension
of the bellhanger suffices to open and discharge the grab, which returns and brings
the bell with it when again hoisted.
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
1 A Self acting Excavator and Elevator or skip, constructed, combined, and
arranged to operate substantially as herein described and illustrated in Fig 2 of the
accompanying sheet of Drawing.
2 In a self acting Excavator, the scoops with combined plain cutting edges and
teeth, substantially as described.
3 In a self acting Excavator and Elevator or skip, the frame and Rigging
constructed substantially as described.
4 In a self acting Excavator and Elevator or skip, the outrigger rail guide, as
described and for the purpose specified.
5 In a self acting Excavator and Elevator or skip, the fender frames constructed
and combined with the Rigging substantially as described for the purpose specified.
6 In a self acting Excavator and Elevator or skip the excentric windlass con-
structed and arranged to operate substantially as set forth.
7 In a self acting Excavator and Elevator or skip, the dog substantially as
described together with its adjuncts and modifications for opening and keeping
open such implements as specified.
8 In an Excavator, operating the excavating scoops or analogous implements by
a percussive or hammer action substantially as set forth.