Improvements in Dredging and Excavating Machinery.
Year: 1891

page_text: Date of Application, 25th May, 1891-Accepted, 18th July, 1891
COMPLETE SPECIFICATION.
Improvements in Dredging and Excavating Machinery.
I, JOHN KENNEDY, of the City of Montreal, in the District of Montreal, and
Province of Quebec, Canada, Civil 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 has reference to the mechanism for lowering, holding and raising
the buckets of dredges and is specially adapted to dredges working at great depth
of water.
It is also applicable to excavators working on land.
It may be briefly described as consisting in making the main drum conical for the
whole, or a considerable portion of its length, the wire rope or chain (by which
the dipper is suspended) being secured thereto at any point of the least diameter.
This drum will be connected by friction clutches with double operating gearing,
driven from suitable engines.
For full comprehension however of the invention, reference must be had to the
accompanying drawings forming part of this Specification, in which
Figure 1 is a part view of the deck of a dredge showing the main engine &c.,
Figure 2 a side view of boom &c., showing bucket at lowest point,
Figure 3 a detail view of drum, and
Figure 4 a view of friction clutch connection.
Like symbols indicate the same parts.
A is the main drum, conical or partly conical in shape, as shown, grooved to
receive the wire rope B secured to it at some part of its least diameter, C C are
double gear wheels, arranged at the ends of the barrel of the drum and connected
therewith by friction clutches, preferably worked by steam cylinders operated by
levers under the control of the engineer.
These friction clutches may be of any type ordinarily employed in dredges, but
I prefer the "cone" clutches shown in Figure 4 in which the double gear wheels
can be moved along the axle (on which they together with the cone of drum A
are loosely mounted) by means of levers, so as to bring the conical surface X,
projecting from the side of the spur wheel, in contact with the corresponding
return surface Z of the drum.
The wheels are driven from cylinders D D acting through transverse shafts d d
and suitable spur and pinion gearing to give the speed desired.
The wire rope B, by preference passes at the dredge end of the boom or crane
under the sheave E and at the outer end over the sheave F.
The construction of the boom, or crane, dipper, or bucket and arm, and of the
swinging mechanism differ in no way from the now existing approved types and
form no part of the invention.
This drum A. may be entirely conical but it is preferably made with only the
central part so and with the two ends parallel or nearly so in order to act as
followsThe parallel part of the small end winds in the rope or chain while the
bucket is moving from the point G to the point F, (what may be termed the
entering cut) during which the angle at which the rope acts upon the bucket is
increasing and the digging power of the bucket is therefore increasing until the
full power which the dredge is designed to have is attained at H.
The next part of the drum is made conical and of rapidly increasing diameter,
the effect of this being that while the bucket is drawn from H to L and the angle
at which the rope draws the bucket is still further increased the digging power of
the bucket is kept approximately uniform instead of being dangerously increased
as in ordinary dredges.

page_text: The last part of the drum is made parallel and of large diameter, so that after
the bucket has finished digging it may be rapidly raised to the full height desired,
without increasing the speed of the hoisting engine.
In order to drive the drum which is thus larger than usual it is preferably
provided with a friction clutch at each end, which clutches are separately driven
by one of the gear wheels C C. For large dredges and where great power is
required the drum is also driven with double powered gearing ; the introduction
of the intermediate shaft d and the gear wheels thereon as shewn.
It will thus be seen that by the operation of the apparatus above described the
working strains on the machinery and dredge are equalised and the bucket moved
rapidly when it is so desired and that thus the rate of speed of dredging is increased
and the wear and tear reduced.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same to be performed, I declare that what I
claim is :-
1. In a dredging or excavating machine, the combination of a graduated hoisting
drum operated by an engine, intermediate connecting mechanism, a boom or crane
supporting a dipper handle carrying a dipper, and a hoisting cable connected' to
and wound upon said drum and passing over sheave carried at upper end. of: boom
and attached to dipper, all as herein set forth.
2. In a dredging or excavating machine, the combination of a graduated hoisting
drum operated directly from a double engine; intermediate connecting mechanism;
friction clutches for throwing same in and out of gear; a boom or crane supporting
a differ handle carrying a dipper and a hoisting cable connected to and wound upon
said drum and passing respectively under and over drums E and F at inner and
outer ends of boom and attached to dipper, all as herein set forth..
Dated this 25th day of May 1891
CARPMAEL & Co.,.
Agents for the Applicant.