IMPROVEMENTS IN EXCAVATING MACHINES
Year: 1875

page_text: S
LETTERS PATENT to James Dunbar, of Brixton, in the County of
Surrey, Engineer, and Joseph Ruston, of the Town and County of
Lincoln, Engineer, for the Invention of "IMPROVEMENTS IN EXCAVATING
MACHINES
PROVISIONAL SPECIFICATION left by the said James Dunbar and
Joseph Ruston at the Office of the Commissioners of Patents,
with their Petition, on the 24th December 1875..
We, JAMES DUNBAR, of Brixton, in the County of Surrey, Engineer,
and JOSEPH RUSTON, of the Town and County of Lincoln, Engineer, do
hereby declare the nature of the said Invention for " IMPROVEMENTS IN
EXCAVATING MACHINES," to be as follows:-
:
This Invention relates to improvements in excavating inachines.
:
The base of the machine consists of a rectangular wrought-iron frame
supported on wheels and axles, and provided at each corner with an
adjusting and steadying screw. The front part of this frame is formed

page_text: into a tank to hold the water for the engine, and to serve also as ballast
to weight the machine. The back of the tank is formed of a cross
girder, which serves also to stiffen the frame, and within the outer
frame and between the front and cross girder two longitudinal girders
form the sides of the water tank, and support the sides of a main post
constructed of wrought-iron work. Upon the top of this post is a cast
or wrought iron bracket carrying the top centre of a swinging jib, the
bottom pivot of which is supported in a step resting on a framing
formed of wrought-iron girder work extending beyond the front of the
bottom frame, and supported beneath by a bracket. The jib is con-
structed of openwork wrought-iron framing. The bottom of the vertical
pillar of the jib terminates in a large horizontal wheel grooved around
the periphery to receive a chain to give the swinging motion required to
the jib. At a convenient point on the top side of the jib is an axle
carrying two spur pinions and a chain wheel, which spur pinions gear
into corresponding racks secured to the handle of the excavating bucket,
so that by giving motion to the spur pinions by means of the said
chain wheel actuated by an endless chain passing also round a small
chain wheel near the foot of the jib, and running on an axle provided
also with a hand and brake wheel, the excavating bucket may be drawn
in or extended, and so the depth of cut regulated as required. On the
spindle carrying the said spur pinions, and between same, is an arm
working freely on the spindle, and carrying at its outer end rollers
which run on the opposite side of the handle of the excavating bucket,
and so keep the racks in gear with the pinions. To the end of the said
handle, which is made by preference of wood, the excavating bucket is
attached on a centre, so that the angle of the bucket in relation to the
handle may be adjusted. This adjustment is effected by means of union
screws, or by two chains passing round wheels on the opposite sides of
the handle, the said wheels receiving motion by means of a worm and
wheel.
The excavating bucket is formed tapering, and of larger area at
the bottom than at the mouth, thereby ensuring a better delivery of the
material excavated, and the mouth is fitted with a steel cutting edge
and spike teeth. The bottom is a wrought-iron plate attached to the

page_text: In working on a clay soil the door is made to fit within the bucket,
and not up against the edge. The bucket, radiating from the toothed
pinions on which the handle bears, is raised by means of a chain and
three sheaves, one being attached to the bale of the bucket, and the
others on the outer end of the jib on separate axles, the chain passing
backwards through the central slot in the bucket handle, thence between
two horizontal guide sheaves, and over a vertical sheave to the winding
drum of the steam engine, which is placed on the rear part of the frame.
A separate winding drum with brake, band, and friction or other clutch
is provided for drawing the bucket back by means of a chain working
under and between guide rollers, and passing and attached to the handle
of the bucket, whilst there is a third winding drum for swinging the jib
to the right or left as required by means of a chain passing over and
under the said drum and between two guide sheaves, and thence round
the large wheel at the foot of the vertical pillar of the jib. Provision is
also made for swinging the jib by hand by means of a pitch chain and
pinion and a hand wheel. Gearing for propelling the machine along the
ground by steam power is also provided.
In some cases we mount the engine and the whole of the machinery
for actuating the excavating bucket, so as to turn with and upon the
same centre as the swinging jib, thus enabling the excavating and
delivery to be carried on at any point within the circle described by
the jib.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, JAMES
DUNBAR, of Brixton, in the County of Surrey, Engineer, and JOSEPH
RUSTON, of the Town and County of Lincoln, Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fourth day of December, in the
year of our Lord One thousand eight hundred and seventy-five, in the
thirty-ninth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto us, the said James Dunbar and Josephi
.

page_text: Ruston, Her special license that we, the said James Dunbar and Joseph
Ruston, our executors, administrators, and assigns, or such others as we,
the said James Dunbar and Joseph Ruston, our executors, administrators,
and assigns, should at any time agree with, and no others, from time
to time and at all times thereafter during the term therein expressed,
should and lawfully might make, use, exercise, and vend, within the
United Kingdom of Great Britain and Ireland, the Channel Islands,
and Isle of Man, an Invention for " IMPROVEMENTS IN EXCAVATING
MACHINES," upon the condition (amongst others) that we, the said
James Dunbar and Joseph Ruston, our executors or administrators, by
an instrument in writing under our or their hands and seals, or under
the hand and seal of one of us or them, should particularly describe and
ascertain the nature of the said Invention, and in what manner the
same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately
after the date of the said Letters Patent.
NOW KNOW YE, that we, the said James Dunbar and Joseph
Ruston, do hereby declare the nature of the said Invention, and in
what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement thereof, that is to
say :-
•
This Invention relates to improvements in excavating machines.
And in order that the same may be clearly understood, and readily
carried into effect, we will proceed to describe it with the aid of the
accompanying Drawings, reference being had to the letters and figures
marked thereon, and in which Fig. 1 is a side elevation of an excavating
machine constructed according to our Invention; Fig. 2, a plan of same;
and Fig. 3, a front elevation.
Figs. 4 and 5 are side elevations of other forms of excavating machines
constructed according to our Invention.
Like letters or figures indicate the same or corresponding parts in the
several Figures.
The base A of the machine (see Figs. 1, 2, and 3) consists of a
rectangular iron frame, which, for convenience of carriage and erection,
may be constructed in two or more parts to be united by bolts a (see a
Fig. 1). This frame A is supported on four or more wheels B, and is

page_text: provided at each corner with an adjusting and steadying screw.C working
through a bracket bolted to the frame. In the front part of frame A is
formed a tank to hold the water required for the engine, which tank
and water serve also as ballast to weight the machine. The back of this
tank (which is of the same depth as the frame) is formed by a transverse
girder, the end of which is shewn by dotted lines on the side of the
frame at D (Fig. 1); it is not dotted in plan to avoid confusion of lines.
This girder serves also as a brace to stiffen frame A. The front of the
frame serves for the front of the water tank, whilst the sides are formed
by two girders fixed longitudinally between cross girder D and the front,
of the frame. The front ends of these girders are shewn by dotted lines,
at E (Fig. 3); they serve also to support the sides of a main post F,
which is constructed of wrought-iron plates stiffened with angle irons,
and is braced by internal wrought-iron stays, and further stiffened at the
base by gusset plates f, and at the top by wrought-iron brackets G,
having a stiffening plate at back extending across the front of the post.
This main post F projects out at top at F to support a casting H, which
casting carries the top centre of the swinging jib I, the bottom pivot of
which is supported in a step resting on a framing J formed of a girder
curved round, and the inner ends of which are carried right through to
the cross girder D for strength, the front projecting part being further
stiffened by a bracket K underneath. The jib I is constructed of open
wrought-iron framing, as will be well understood from reference to the
Drawings. The bottom of the vertical pillar of the jib terminates in a
large horizontal wheel L grooved round the periphery to receive a chain
to give the required right-and-left swinging motion to the jib. Mounted
in bearings at a convenient point on the top side of the jib is an axle
carrying two spur pinions M, and a pitch chain wheel N; these spur
pinions gear into corresponding racks O secured to the back of the
handle of an excavating bucket P (the teeth of the racks being
strengthened by a web at the sides). Motion is imparted to the spur
pinions through the medium of the chain wheel and an endless chain,
which latter passes also round a smaller chain wheel (near the foot of.
the jib), on the axle of which is also a hand and brake wheel Q, the
brake being applied when required by foot lever and strap, as shewn.
By thus giving motion to the spur pinions from the hand wheel Q the
excavating bucket may be drawn in or extended, and so the depth of
cut regulated at pleasure. On the spindle carrying the spur pinions M
and between same is an arm Ṛ working freely, and carrying at its

page_text: outer end two rollers S, which run on the contiguous or outer side of
the handle of the excavating bucket, and so keep the racks O in gear
with the spur pinions. The handle of the bucket is made, by pre-
ference, of wood, the sides being formed each of stout timber, the two
being united at the ends by bolts and distancing pieces. To the end of
this handle is attached on a centre p an excavating bucket, so that the
angle thereof in relation to the handle may be altered and adjusted as
required. This adjustment is effected by means of union screws pl
attached as shewn; or it may be effected by having a chain wheel on
each side of the handle, and a pitch chain passing over each to the
opposite corners of the same side of the bucket, so that by actuating
the wheels by a hand wheel, or otherwise, the position of the bucket
may be altered as required. The bucket P is made tapering and of
larger area at the bottom or outlet than at the mouth for the
purpose of
ensuring an easy delivery of its contents when the bottom is removed or
opened for that purpose. The bottom consists of a wrought-iron plate
hinged to the bucket, and provided with a spring latch or bolt, so as to
fasten readily when closed, or be easily withdrawn by the man on the
machine by a line T when the bottom is required to fall.
For excavating in clay the door or bottom is made to fit within the
bucket, and not up against the edge, so that the door in being closed
may clear its way. The mouth of the bucket is fitted with steel cutting
edge and spike teeth. The bucket, radiating from the spur pinions M,
on which the handle bears, is raised and drawn through the soil to be
excavated, and so filled by means of a chain U passing over three
sheaves, one being attached to the bail of the bucket, and the other two
on the outer end of the jib on separate axes, the chain thence passing
backwards through the central slot in the bucket handle, and between
two guide sheaves V and over a vertical sheave W to the winding
drum X. provided with a brake wheel, strap, and foot lever Y, with
counterbalance weight and clutch and hand lever Z. The spindle of this
drum is driven direct from a steam engine x placed on the rear of the
frame.
When the steam is shut off, the brake relieved, and the clutch thrown
out of gear with the drum the weight of the bucket brings it down,
whilst in its descent it may be stopped at any point by pressing on the
foot break lever Y. When the bucket has descended sufficiently it is
drawn back to the position required by a chain 6 attached to the lower

page_text: end of the bucket handle, and passing in at the front of the machine
under a horizontal and between two vertical guide rollers c to a drum d.
The spindle of this drum receives its motion from that of drum. X by
spur gearing e, a clutch and hand lever j being provided to throw it in
and out of gear as required. A brake wheel, band, and foot lever with
counterbalance weight (g) is also provided to stop the motion of the
bucket exactly wherever required. The swinging of the jib to right or
left is effected by means of a chain passing round the large horizontal
wheel L at the foot of the vertical post of the jib, the two ends of the
said chain leading between guide rollers h direct to a a drum i, one end
passing over and the other under the same, so that by reversing the
motion of the drum the jib may be swung to right or left as required.
This drum receives its motion by bevil gearing k from the axle of
drum d, the reversing tooth gearing, friction clutch, and lever m being
provided to reverse or stop the motion as required. A brake wheel,
strap, and foot lover o are also provided to check the motion of the jib as
soon as required. The propulsion of the machine along the ground is
effected by an endless pitch chain q passing at one end round a pitch
wheel on the axle of the front wheels B, and at the other end round
another pitch wheel r, on the axle of which is a worm wheels driven by
a vertical worm t receiving its motion from the horizontal bevil wheel u
actuated by the reversing tooth gearing, friction clutch, and lever v.
.
The top of frame A is boarded over with stout deals to form a flooring.
This is shewn in side view in Fig. 1, but not in plan at Fig. 2, as the
lines would cause confusion.
It will be obvious that two jibs and buckets with a double set of
actuating gearing may be used on one base as one machine.
Figure 4 illustrates a form of our improved machinery, wherein the
engine and the whole of the machinery for actuating the excavating
bucket are mounted and arranged to turn with and upon the same
centre as the swinging jib, thus enabling the excavating and delivery to
be carried on at any point within the circle described by the jib.
The construction and use of the several parts are evident from the
Drawings when taken in conjunction with the description of the machine
already given.
Fig. 5 illustrates a further form of our improved machine, where the
elevating of the bucket is obtained from one stroke of a steam or water

page_text: cylinder y, the motion thus obtained being multiplied by the lifting
chain of the bucket passing round two or more sets of pulleys, one set of
such pullies being moved by the piston rod to or from the other set.
The swinging of the jib is obtained by another of such cylinders y
actuating a chain passing two or more times round a large drum fixed
rigidly at the lower end of the post on which the jib turns, the two ends
of such chain being attached to the opposite sides of the piston, so that
the up stroke of the piston will swing the jib in one direction and the
down stroke in the other.
Two or more of such cylinders may be used in combination. This
being an action well understood by engineers further detailed description
is unnecessary.
1
In witness whereof, I, the said James Dunbar, on behalf of myself
and the said Joseph Ruston', have hereunto set my hand and
seal, this Twenty-third day of June, in the year of our Lord One
thousand eight hundred and seventy-six.
Witness,
JOHN W. GRAY, C.E.,
Patent Agent,
16, Southampton Buildings,
JAMES DUNBAR. (L.S.)
W.C.