Improved Means applicable for Use in Working Grab-dredgers.
Year: 1899

page_text: Date of Application, 5th Apr., 1899
Complete Specification Left, 1st Jan., 1900-Accepted, 5th Apr., 1900
PROVISIONAL SPECIFICATIOA.
Improved Means applicable for Use in Working Grab-dredgers.
We,. WILLIAM DENT PRIESTMAN, of Holderness Foundry, and HAROLD
RICHARDSON, of 57, Walmsley Street, both in the Town and County of Kingston-
upon-Hull, Engineers, do hereby declare the nature of this invention to be as
follows:-
-
This invention relates to dredging machines of the "grab" type, and is
designed to enable the sliding weight and multiple-rove chain, at present
commonly employed in automatically opening and closing the grab, to be. dis-
pensed with.
A grab-dredger constructed according to our improved method is provided
with a winding barrel, a spring, which may conveniently be arranged within
the barrel, or otherwise, and a strap or other friction-brake. The relation of the
barrel, the spring and the winding chain are such that when the grab is in its
highest position, the opening chain is wound upon the barrel, but the spring is
unwound. As the grab is lowered, the opening chain rotates the barrel, and, in
so doing, winds or compresses the spring. When the grab is lifted, the energy
stored in the spring operates to rotate the barrel in the opposite direction, and
thus to re-gather the opening chain.
Improved Means applicable for Use in Working Grab-dredgers.
We, WILLIAM DENT PRIESTMAN, of Holderness Foundry, and HAROLD
RICHARDSON, of 57, Walmsley Street, both in the Town and County of Kingston-
upon-Hull, Engineers, 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 dredging machines of the "grab" type, and is
designed to enable the sliding weight and multiple-rove chain, at present com-
monly employed in automatically opening and closing the grab, to be dispensed
ith

page_text: A grab-dredger constructed according to our improved method is provided with
a winding barrel, a spring, which may conveniently be arranged within the
barrel, and a strap or other friction-brake. The relations of the opening chain to
the barrel and spring are such that when the grab is in its highest position, the
chain is wound upon the barrel, but the spring is unwound. As the grab is
lowered, the opening chain rotates the barrel, and, in so doing, winds or com-
presses the spring. When the grab is lifted, the energy stored in the spring
operates to rotate the barrel in the opposite direction, and thus to re-gather the
opening chain.
An example of the manner in which our invention may be carried out is
illustrated in the accompanying drawings, whereof Fig. 1 represents a longi-
tudinal section of a winding barrel provided with a spring arranged in an annular
chamber formed, at one end thereof. Fig. 2 is a corresponding end view (the cover
plate pertaining to the spring-enclosing chamber being removed), the
being provided with a strap-brake. Fig. 3 is a side elevation, illustrating means
for arresting the rotative movement of the barrel.
barrel
A is the winding barrel which receives the opening chain B. One end of the
barrel is formed with a recess or annular chamber a, wherein the spring C is
located. The outer extremity of this spring is attached to the periphery of the
enclosing chamber, whilst its inner extremity is secured to the squared portion
of the shaft D, whereon the barrel A is mounted. a¹ is a cover-plate for closing
the chamber a. During the lowering of the grab and the concurrent paying out
of the chain B and the rotation of the barrel, the spring C is wound upon the
shaft D. The energy thus stored is available for effecting the re-winding of the
opening chain upon the barrel during the raising of the grab.
Although, for the purpose of illustration, we have shewn a helical spring
enclosed within a chamber formed in the barrel, it will be obvious that other
forms of springs may be employed for accomplishing the objects in view, and
that they may be arranged in other ways.
For arresting the motion of the barrel; various forms of braking devices,
adapted to the conditions of working prevailing, may be employed. Referring
to Fig. 3, the shaft D is mounted in an eccentric E°, capable of being rotated in
its bearing E¹ by means of an arm E; the outer end of the said arm being
attached to a nut e, through which works the threaded shaft e¹. By means of a
hand-wheel e, the shaft e¹ may be rotated, the nut e raised or lowered, and the
eccentric rotated in its bearing, with the result that the shaft D is either lowered
or raised, and the periphery of the barrel A brought out of or into contact with
the brake-block F.
These particular means for retarding or arresting the rotation of the barrel
are not however essential to our invention, which consists primarily in the
herein before described means for dealing with the opening 'chain. In Fig. 2,
we have indeed shewn the winding barrel fitted with an ordinary friction-strap.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we claim :-
1. The herein described means applicable for use in working grab-dredgers,
comprising a barrel for the reception of the opening chain, a spring and a braking
or retarding device; these being arranged in such a manner that, whilst the grab
is being lowered and opened and the opening chain paid out, the spring is wound
or compressed, the energy thus stored subsequently operating to rotate the
barrel in the reverse direction and to re-wind the opening chain.
2. In a grab-dredger, the herein described means for working the opening
chain, arranged or operating substantially as described with reference to the
accompanying drawings.
3. In a grab-dredger, the combination with a barrel and spring for working
the opening chain, of a breaking device comprising a rotatable bearing wherein
the barrel-shaft is eccentrically mounted, a stationary brake-block, and means

page_text: for rotating the said bearing and thereby bringing the circumference of the
wheel into frictional contact with the said brake-block, substantially as set
forth.
Dated this 28th day of December 1899.
For the Applicants,
G. G. M. HARDINGHAM,
Chartered Patent Agent,
Clun House, Surrey Street, London, W.C.