Improvements in the Construction of Grab Excavators.
Year: 1893

page_text: Date of Application, 6th July, 1893
Complete Specification Left, 6th Apr., 1894-Accepted, 12th May, 1894
PROVISIONAL SPECIFICATION.
Improvements in the Construction of Grab Excavators.
I, GEORGE WATERS of 50 Francis Street, The Denes, Tyne Dock in the
County of Durham, Engineman do hereby declare the nature of this invention to be
as follows:-
This invention relates to Improvements in the Construction of Grab Excavators.
To effect my purpose I propose to connect to the sliding cross-bar of a
"Priestman" or other similar grab excavator a rigid bar or beam of suitable
length so that the opening or shutting of the grab-buckets may be more or less
dependent thereon.
propose to adapt such an appliance for hand use in the cleaning out of wells
or cesspools on a small scale. Thus I may lower the grab with a rope or chain and
when the weight of the grab is on the rigid bar or beam the buckets will open;
then by braking or otherwise locking the rigid bar and lifting the grab itself the
buckets will be forced into the material to be lifted.
Such an appliance may be specially useful for dredging in shallow waters as the
rigid bar can be operated by hand and its length will not be a material
circumstance.
For use on crane-jibs and the like a brake device may be arranged at the
jib-head or worked from the crane engine to lock or unlock as required the rigid
bar when lifting the grab-frame for the purpose of filling the buckets or the bar
might be mechanically actuated by rack and pinion or equivalent gear to force it
through or into the material to be dredged.
The bar may be guided by passing through the upper hoop of the grab-frame and
can either be worked by hand power or mechanically as above foreshadowed.
Dated this 5th day of July 1893.
A. CRAWHALL CHAPMAN,
3, St. Nicholas Buildings, Newcastle-on-Tyne, Patent Agent.
COMPLETE SPECIFICATION.
Improvements in the Construction of Grab Excavators.
I, GEORGE WATERS of 50 Francis Street, The Denes, Tyne Dock in the
County of Durham, Engineman, 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 Improvements in the Construction of Grab Excavators.
To effect my purpose I propose to connect to the sliding cross-bar of a
"Priestman
or other similar grab excavator a rigid bar or beam of suitable
length so that the opening or shutting of the grab-buckets may be more or less
dependent thereon.
I propose to adapt such an appliance for hand use in the cleaning out of wells or
cesspools on a small scale. Thus I may lower the grab with a rope or chain and
when the weight of the grab is on the rigid bar or beam the buckets will open;
then by braking or otherwise locking the rigid bar and lifting the grab itself the
buckets will be forced into the material to be lifted.

page_text: Such an appliance may be specially useful for dredging in shallow waters as
the rigid bar can be operated by hand and its length will not be a material
circumstance.
For use
on crane-jibs and the like a brake device may be arranged at the
jib-head or worked from the crane engine to lock or unlock as required the rigid
bar when lifting the grab-frame for the purpose of filling the buckets or the bar
might be mechanically actuated by rack and pinion or equivalent gear to force it
through or into the material to be dredged.
The bar may be guided by passing through the upper hoop of the grab-frame
and can either be worked by hand power or mechanically as above foreshadowed.
I will fully describe my invention with reference to the accompanying drawings
in which
Figure 1 represents a front view with the grab shut and suspended by the ordinary
lifting and lowering chain or rope, the pole being free:
Figure 2 shows a similar front view but with the grab open and the lifting chain
or rope loose, the grab being suspended by the pole :
Figure 3 shows a device for guiding and clamping or freeing the pole at the
jib-head of a crane and
Figure 4 shows a side view of the lower end of the pole as it is when in position
suspending the grab as hereinafter described and in the following description like
marks of reference designate like parts.
Referring to the drawings it will be observed that the grab itself G is substan-
tially of the ordinary type in common use but it may be made of a much lighter
description than the ordinary type as the pole, hereinafter described, has the same
effect as increased weight in the grab for penetrating hard material. The lifting
and lowering chain or rope R passes through a plate P on the grab frame (where if
desirable there may be a friction roller to ease the passing therethrough of the chain
or rope) and thence downwards where it is shown bifurcating to pass under
pulleys a and thence again upwards so that the ends of the chain or rope may be
secured to the eyes on the ferrules F of the transverse bar B as shown.
Between the ferrules or their equivalent just alluded to aud encircling the
bar B the forked lower end of the pole N is designed to work as hereinafter
described.
The operation of the device is as follows:
Suppose it is required to use the device manually the grab may be lowered by the
chain or rope passing through the band of the operator until the grab is nearly at
the bottom or on the ground: the operator will then let go the chain and suspend
the grab by the pole only which he will hold in his hands: this allows the grab to
open; the pin or bolt in the lower end of the pole will then suspend the grab as
shown in Figures 2 & 4. The grab may then be dropped onto the ground: the
operator will then force the pole against the cross-plate M of the frame and simul-
taneously he will heave up the lifting chain: the latter operation causes the grab
buckets to shut and the rigidity of the pole held as described causes the buckets to
penetrate the mud or earth or other material deeply while the grab buckets are
closing when the buckets are shut by the lifting, the grab and its load can be raised
by the lifting chain or rope. To open the grab, the pole must again be used to
suspend it, the lifting rope being slackened.
In a mechanical application of the device the grab may be suspended by rope
or chain R from a jib-head or beam as shown in Figure 3. A guiding device
consisting of a ball 4 with an aperture for the pole to pass through may work in a
cup-bearing 5 and an extension e of the same or another casting may be used to
mount an eccentric E or equivalent device in contiguity to the pole which is
arranged to pass freely through or between the cheeks of the extension as shown.
A lever L on the eccentric axle may be operated by chain rope or rod gear by the
crane or other engine-man so as to enable him to clamp and fasten the pole in the
extension aforesaid at will or to release it.
Thus the grab may be lowered by the heaving chain with the pole free to pass

page_text: :
the eccentric or clamp: when near the ground the clamp is applied to the pole to
suspend it and the grab thereby the lowering of the chain allows the grab to-
open releasing the clamp allows the grab to fall onto the ground: the pole.
follows it and its lower end drops onto plate M in which position the pole may
again be clamped by the eccentric as above described: the heaving up of the lifting
chain closes the grab buckets and the rigidity of the pole held or clamped as
described causes the buckets to deeply penetrate the material to be excavated..
When the grab is closed the clamp is released and the grab with its load and pole
may be lifted to discharge the material, the clamp must again be applied to suspend
the grab by the pole and the lowering of the chain or rope will then allow the
grab to open and discharge its contents.
The ball and cup-bearing device provides for any slight variation from the
perpendicular in lowering or raising the pole.
In the drawings two barrels or pulleys a are shown to enable the pole to act.
radially on the grab: instead of this arrangement one centre barrel might equally
well be employed in which case the base of the pole would require to be forked.
to work over the medial barrel or pulley the ends of the forks acting on the plate M
as described with reference to the arrangement shown.
The clamping device or eccentric and guiding device may similarly be modified
in design or in position as regards the jib without departing from the spirit of the
invention hereinabove described and it will be obvious that instead of allowing the-
pole to descend by gravity as described and to ascend with the grab it might be
operated to ascend and descend by means of a simple rack on the pole gearing
with a pinion at the jib-head worked or caused to revolve by the crane or other
engine.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The improvement in the construction of manually-worked grab excavators.
consisting in the use and application of a rigid pole in combination with the grab.
mechanism arranged and adapted to be operated substantially as and for the purposes.
herein set forth.
2. The improvement in the construction of mechanically-worked grab-excavators.
consisting in the combination with the grab mechanism of a rigid pole adapted to.
be clamped or secured and released at will the parts being arranged designed and
adapted for use substantially as and for the purposes herein set forth.
3. The combination of parts forming the improved construction of grab
excavators arranged and adapted for use substantially as and for the purposes.
specified.
Dated this 5th day of April 1894.
A. CRAWHALL CHAPMAN,
3, St. Nicholas Buildings, Newcastle-on-Tyne, Patent Agent..