Improvements in Grabs for Excavating and Elevating Clay, Coal, Coke, or other Material.
Year: 1894

page_text: Date of Application, 1st Nov., 1894-Accepted, 15th Dec.,
1894
Improvements in Grabs for Excavating and Elevating Clay, Coal,
Coke, or other Material.
We, GEORGE JAMES HONE, of East Ham, in the County of Essex, Mast
Maker, and CECIL WILSON, of Orchard Yard, Blackwall, E., 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 :—
This invention relates to various improvements in the construction of excavators
or grabs of the double and of the single chain type which are provided with an
arrangement of sheaves mounted in sliding and fixed parts of the excavator frame
whereby a more powerful purchase is obtained on the material to be excavated and
the apparatus operates more efficiently than hitherto and our invention further
relates to details in the construction of such grabs or excavators.
We will first describe a grab or excavator of the double chain type constructed
according to this invention in which one set of sheaves is mounted in a crosshead
sliding in guides the block for the second set of sheaves being secured to the base
of the said guides, and in order that the invention may be clearly understood we
will describe it with reference to the accompanying drawings which illustrate a
convenient way of carrying out this invention.
Figure 1 shews the apparatus in side elevation with the blades or buckets open,
Figure 2 shews the apparatus closed and Figures 3 and 4 are plan views of the
sheave blocks, Figure 3 showing the sheave block on the sliding crosshead and
Figure 4 the sheave block fixed at the lower part of the apparatus.
Figuro 5 shews in section drawn to a larger scale a spring buffer to which the
end of the hauling chain is attached for deadening the shock given by 'n suddon
pull or jerk on the hauling chain to that part of the apparatus to which the
spring buffer is now attached.
A are blades or buckets pivotted at a to the lower end of a guide frame C.
D are tie rods hinged at their lower ends d to the outer ends of the blades or
buckets A and at their upper ends to the crosshend E sliding in the guide frame C,
which crosshead is provided with sheaves e e. To the lower end of the guide
frame C is secured a pulley or purchase block F containing sheaves
relative position of the sheaves in the crosshead E and in the block F being
shewn in plan views Figures 3 & 4.
The
G is a balanced chain attached to the crosshead at g for retaining the said
crosshead in position. His the main hauling chain passing from the crane through
the central hole in the crosshead E down through the hole in the block F and
round the central sheave on the said block F: the chain then passes up over the
shenve e on the crosshead E returning down round the sheave on the block F
and up again round the sheave e' on the crosshead E then down round the sheave
on the block F and finally up to the crosshead E to the lower side of which it is
attached through a spring buffer K-Figure 5. The spring buffer K is formed
by elastic blocks with interposing washers up through which passes the
connecting link k³ having a screw nut on the end of the link bearing on the top-
most washer all being enclosed in a cylindrical case with a metal cap. We
have described this buffer as suitable for the apparatus but other known forms of
spring buffers may equally well be used.
When it is desired to close the blades or buckets A for the purpose of exca-
vating aud removing the material, the #nid buckets being in an open position shewn

page_text: in Figure 1 and resting on the said material, the main chain H is hauled in depressing
the crosshead E and causing the tie rods D to be thrust down so that the blades
or buckets A excavate the material and meet together in a closed position beneath
the said material as in Figure 2. The apparatus may then be raised by continued
hauling of the main chain H; and may be swung round to the desired position
for discharging the load, which is effected in the ordinary manner by keeping
the balance chain taut and allowing the main chain to run out. The apparatus will
then re-assume the position shewn in Figure 1 and is ready for lowering again on
to the material to obtain a fresh load.
By the arrangement of sheaves and pulley blocks on the sliding and fixed parts
as hereinbefore described, an increase of purchase is gained which may be varied
by using a greater or less number of sheaves in the pulley block and crosshead,
according to the consistency of the material to be operated on and the greater or
'less purchase required to be exerted on the material to be removed.
We do not limit ourselves to the precise details of the apparatus hereinbefore
described which may be altered to suit the requirements of each particular case.
We will now describe this invention as applied to a single chain grab in which
the sliding crosshead is made with a removable pin, a locking pin with balanced
weight and lever being employed for attaching a sliding pulley bluck automatically
to the said crosshead, the fixed pulley block in this case being secured to the upper
end of the guide frame.
Figures 6 and 7 shew in elevation in closed and open positions respectively a
single chain grab or excavator constructed according to this invention, and
Figure 8 is an enlarged view of the locking-pin and balauce weight lever berein-
after referred to.
A are blades or buckets pivotted at a to a frame B attached to the lower end of
an upright guide frame C. D are tie rods hinged at their lower ends to the
buckets A and at their upper ends to the underside of a crosshead E sliding verti-
cally in the guides formed by the upright frame C.
In the upper side of the crosshead a recess or slot e is formed in which is held by
a pin or bolt a removable pin provided with a semicircular notch. Above the
crosshend E sliding also in the guides C is a pulley block G containing two
sheaves g and g and having a recess or socket formed on its underside into which
fits the pin of the crosshead E; the sliding crosshead and block when brought
together are locked by means of a recessed or notched horizontal ping mounted on
the block G (Figure 8) taking into the notch on the crosshead pin F. The cross-
head is released from the block by causing the notch in the pin y³ to come opposite
the notch in crosshead piu F, the pin being turned by means of a releasing
lever H carried on one end of the said pin g. The lever H is provided with. a
lotted weight which serves to retain the pin giu engagement with the notch
on the pin F of the crosshead E and a balance weight for raising the lever H
alter it has passed through the ring K so that when descending the lever H may
catch against the ring K as hereinafter described. is a stop pin on the lever H
limiting the downward and upward movement of the said lever by coming in con-
1act with projecting parts gª and gª on the sliding block G.
Jis a liorizontal plate secured on the upper end of the guide frame C forming a
cap thereto and carrying a loose vertical sheave j, holes are formed in the said plate
through which the chain for hauling the apparatus is passed.
A ring K is hung from the jib head of the crane at any desired height of
suflicient diameter to allow the vertical frame C to enter it but through which the
releasing lever H is unable to pass without being depressed or raised.
The hauling chain L from the crane passes down through the central hole of the
plate J under the sheave g' in the sliding block G and up through the second hole
in the plate J over the sheave in the said plate and down through the third hole
therein and under the sheave in the block G and up again to the plate J to which
it is attached by means of a spring buffer K' such for example as that proviously
described in Figure 5 of the accompanying drawings.

page_text: When it is desired to work the apparatus say for landing coal the apparatus is
lowered and when the buckets which are now open (as in Figure 7) come in contact
with the material to be raised the sliding block G runs down the guides C by its
own weight until the crosshead pin F enters the hole in the bottom of the block G
and is then by the weighted lever H securely locked together. On commencing to
baul on the chain L the pivotted buckets are gradually drawn together into a closed
position by the crane chain drawing up the tie rods by the sliding block and cross-
head until the apparatus assumes the position shown in Figure 6 and the grab is
closed. In this position the grab may be raised to the required height the guide
frame C passing through the ring K until the releasing lever H is depressed by
coming into contact with the said ring; having passed through the grab is swung
round to the desired position and then lowered again through the ring K; in
descending the arm of the releasing lever H catches against the top edge of the
ring K turning the locking pin so that the notch therein comes opposite the notch
in the pin of the crosshead E which falls from the block G permitting the
bucket A to open and discharge its contents.
A vertical oil checking cylinder or dash pot M is fixed at its upper end to the
plate J, the piston rod N passing through a gland at the bottom end of the
cylinder through a clearing hole in the block G and being attached at its lower
end to the crosshead E, by this means the gradual opening of the buckets or
blades A is secured and any shock to the machine and scattering of material is
avoided.
On lowering clear of the ring K the releasing lever H and locking piu are
caused to assume their normal position as in Figure 6 by means of the balance
weights and the apparatus is again ready to be lowered to take a fresh charge.
The crosshead pin and locking pin are preferably hardened in their notches at
their working surfaces; this may be effected by inserting dovetailed pieces of
hardened steel or other suitable material in the said notches and then removing
part of the anid hardened material leaving sufficient in the notches to form the
hardoned bearing surface as seen at Figure 7.
Crossheads formed with a removable projecting part or pin F enable a ready
change of the removeable part to be effected when dosired, for instance when
damaged or broken and constitute a great improvement on the crossheads which
have been in use hitherto.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
11 •
1. In excavators or grabs of the double or single chain type the combination of
sheaves mounted in sliding parts and sheaves mounted in fixed parts of the
apparatus for obtaining an increase of purchase on the material to be excavated
substantially as herein before described.
2. In excavators or grabs of the double chain type the arrangement of sheaves
on a lower fixed block in combination with sheaves on an upper sliding crosshead
for receiving the crane hauling chain substantially as herein before described with
reference to the accompanying drawings.
3. In excavators or grabs of the double chain type the combination with the
sheaves on the block F of the sheaves on the crosshead E and a spring buffer
attached to the said crosshead substantially as and for the purposees herein before
described with reference to Figures 1, 2, 3 and 4 of the accompanying drawings.
4. In excavators or grabs of the single chain type a sliding crosshead provided
with a removeable engaging device substantially as hereinbefore described.
5. In excavators or grabs of the single chain type a sliding crosshead with a
removeable device engaging with a locking pin on a sliding block in combination
with a weighted balance lever substantially as and for the purpose herein before
described.
6. The general construction combination and arrangement of parts constituting

page_text: improved grabs for excavating substantially as hereinbofore described with
reference to Figures 6 and 7 of the accompanying drawings.
Dated this 1st day of November 1894.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, Loudon, W.C., Agents.