Year: 1898

page_text: I, HENRY GRAFTON, of 113, Cannon Street, in the City of London, Engineer, do
hereby declare the nature of this invention to be as follows:-
This invention relates to improvements in the mechanism of cranes and other
machinery for operating grab dredgers, more particularly those mounted upon
vessels.
The grab is supported by an arm pivotted to a vertical hollow crane post and is
raised and lowered by means of a chain passing vertically through the post.
Attached to the post below the deck is a counterweight to balance wholly or in part
the weight of the arm and grab.
For actuating the valve of grab cylinder I fit a hand wheel round the crane post
controlling a grooved collar acting through a bell crank and rod on the arm supporting
the grab in such a manner that the valve admitting steam to the grab is unaffected
by the position of the jib or arm.
Dated this Fourth day of February
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.
I, HENRY GRAFTON; of 113, Cannon Street, in the City of London, 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 improvements in floating direct-acting grab dredgers
and has mainly for object to ensure stability when the apparatus is mounted and
worked upon a boat of narrow beam such as a canal barge.
This invention consists in mounting the direct acting grab dredger upon an arm
or jib pivoted on a horizontal axis to a hollow crane post and raising and lowering
the jib and grab by a chain which passes through the hollow crane post to hauling
mechanism distant from the crane and preferably placed at the bottom of the vessel,
the counterweighting, in whole or in part, of the pivoted arm, the grab dredger and its
Price 8d 1

page_text: contents, being effected by attaching to the crane post a counterweight which
rotates with the post so as always to be opposite the grab dredger, the counterweight
being below the deck level so as to ensure the stability of the vessel. For actuating
the valve of the grab cylinder in any position of the jib, a hand wheel mounted to
turn on the crane post engages with a grooved collar capable of sliding along the
joint pin of the jib, the collar also engaging with a bell crank coupled by a rod with
the valve distributing steam to the grab dredger cylinder. By this means the control
of the valve is unaffected by the angular movements of the jib.
This invention is illustrated in the accompanying drawings forming part of this
Specification, wherein Figure 1 is a diagrammatical side elevation of the grab
dredger, jib, post, and counterbalance, and a longitudinal section of a portion of the
vessel. Figure 2 is a plan with the grab dredger, jib, and part of the deck removed.
Figure 3 is an elevation of the grab dredger and jib in the raised position, and a
cross sectional view of the vessel through the hollow crane post. Figures 4 and 5
are plan and sectional views, on a larger scale, of the valve controlling gear. The
same letters of reference denote the same parts in all the figures.
A is the grab dredger supported on trunnions a by the jib B pivoted by the
horizontal joint pin C to a bracket D which is keyed to the hollow crane post E.
The jib B is raised and lowered by the chain G which passes over a pulley H at the
top of the crane post down through the hollow crane post, and hollow footstep K, to
the bottom of the vessel and leads away to the hauling mechanism. The post E is
supported by the collar bearing J. at the level of the deck and by the footstep K
fixed on the bottom of the vessel, the post E being rotated in either direction by
suitable slewing gear (operating through a chain P and drum R or other suitable
transmission) or retained in any position in which it may be required to work the
grab dredger. Attached to the post E at a point below the level of the deck
diametrically opposite to the jib, is the counter weight L so that it assists in counter-
balancing the weight of the jib, the grab dredger and part of its load, and thus
ensures the stability of the narrow beam vessel. The valve of the grab dredger
cylinder is of the ordinary kind and controlled by a rod m running along the
jib arm B and connected to one arm of the bell crank M the other arm of which carries
a pivoted shoe which engages in the groove of a collar N free to slide on the joint
pin C of the jib, a similar engagement with the same groove of the collar being
made by a hand-wheel O mounted loose on the crane post so that upon angular
motion being imparted to the hand-wheel O the collar N slides on the joint pin C
and imparts a corresponding movement to the bell crank M which in turn actuates
the valve rod m in the ordinary manner..
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what I
claim is :-
1. In a floating dredger the combination of a direct acting grab carried by a jib
pivoted to rise and fall upon a hollow rotating crane post, a guy chain supporting the
jib and passing down through the post to the hauling gear, substantially as
specified.
2. In a floating dredger the combination of a direct acting grab carried by a jib
pivoted to rise and fall upon a hollow rotating crane post, a guy chain supporting the
jib and passing down through the post to the hauling gear, and a counterweight fixed
to the crane post below the deck level, substantially as specified.
3. In a direct acting dredger carried by a rising and falling jib, the gear for
actuating the valve of the dredger cylinder so constructed, combined, and
arranged as to be unaffected by the angular motions of the jib, substantially as
specified.
4. The herein described floating direct acting dredger comprising a direct acting
grab carried by a rising and falling jib pivoted to a hollow rotating crane post, a guy
chain supporting the j. and passing down through the crane post to the hauling

page_text: gear, a counterweight fixed to the crane post below the deck level and gear
independent of the angular motions of the jib, for actuating the valve of the dredger
cylinder, all substantially as specified.
T
FIL
1000
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.