IMPROVEMENTS IN EXCAVATING MACHINES
Year: 1875

page_text: LETTERS PATENT to Benjamin Joseph Barnard Mills, of the Firm of
Harris and Mills, of 23, Southampton Buildings, in the County of
Middlesex, Patent Agent, for the Invention of "IMPROVEMENTS IN
EXCAVATING MACHINES."-A communication from abroad by Oliver
S. Chapman and John Souther, both of Boston, in the State of
Massachusetts, in the United States of America.
Sealed the 6th August 1875, and dated the 6th May 1875.
PROVISIONAL SPECIFICATION left by the said Benjamin Joseph
Barnard Mills at the Office of the Commissioners of Patents, with
his Petition, on the 6th May 1875.
I, BENJAMIN JOSEPH BARNARD MILLS, of the Firm of Harris and
Mills, of 23, Southampton Buildings, in the County of Middlesex,
Patent Agent, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN EXCAVATING MACHINES," a communication to me from
abroad by Oliver S. Chapman and John Souther, both of Boston, in the
State of Massachusetts, in the United States of America, to be as
follows:-
The Invention consists in certain improvements in steam excavators.

page_text: In its general plan and construction the machine is similar to those
now in use, but as heretofore constructed these machines. have been
liable to frequent breakage and disarrangement, involving delays and
'heavy expenses.
The Invention has for its object so perfecting the machine in its
details as to obviate these difficulties, and at the same time render it
much more perfect in its operation.
The drum on which is wound the chain that swings the crane to one
or the other side, as may be necessary to bring the shovel to the required
position, is operated by a gear wheel. As this must be put in motion at
every movement of the crane, and has to be thrown in and out of gear
with bevil gear on another shaft at each movement, it is obvious that
the strain caused by the sudden throwing of it into gear so often will be
very severe on the cogs, and have a tendency to break the said cogs.
To remedy this such wheel is constructed as follows:-The main portion
of the wheel consists of a disc having the cogs cut on its face or
periphery, according as it is intended to be a spur or bevil gear, and
having four or more oblong openings made through it, with a recess in
its rear face to receive a disc which is secured rigidly to the shaft, the
wheel being loose on the shaft. This disc has on its face lugs, which fit
into the openings in the wheel in such manner as to leave a space on
the two sides of the lugs, which spaces are filled with rubber or other
elastic material. A plate or cap is then placed over the face of the
opening and secured by a screw, which confines the rubber in place and
firmly unites the two parts.
It will be readily seen that when the wheel is thrown suddenly into
gear with another wheel which is in motion the shock will expend itself
in a great measure upon the rubber springs, and thereby prevent the
cogs from being broken.
It has been customary to construct the crane with cast-iron plates at
its outer end to receive and hold the end of the brace, but these plates
are liable to break when subjected to the heavy work which the machine
is required to perform..
According to the present Invention the side plates are constructed of
wrought iron with a flange at the top, and with strong cast-iron check
pieces bolted securely at the outer end, thus forming a socket to receive

page_text: and hold the upper end of the brace that will stand all the work and
strain required of the machine.
The shovel is made of metal, and it is provided with heavy steel
prongs, which project at the front. These prongs are intended to
prevent the shovel from injury when brought into contact with stones or
other heavy objects, and also to hook under roots or rocks that cannot
be readily seized hold of by the shovel itself. It has a door hinged so
as to open and permit the contents of the shovel to be emptied at its
rear end when its front end is elevated. In order to permit this door to
be raised far enough to be out of the way, and yet not strike against the
carrying bar, it is suspended by bent arms and hinged on the upper side
of the shovel some distance in front of the rear end. The door is so cut
away on its upper side, in order not to hit the supporting bar when
opened, that it is too narrow to cover the entire rear end of the shovel,
and to make up for this deficiency a second and narrower door is hinged
to the upper rear end of the shovel, in such a manner that when the
main or outer door is closed it will also shut the inner door and hold it
closed.
Whenever the outer door is opened the inner door is released, and
permitted to swing free on its hinges, and by these means the shovel
may be raised at its front end sufficiently to empty it of its contents
almost instantly, and at the same time have the outer door swing
entirely out of the way.
For the purpose of having more complete control of the shovel a
novel style of clutch is employed for throwing the motive parts which
operate the shovel in and out of operation. As usual the shovel is
operated by a chain wound around a drum driven by a gear wheel,
which engages with a smaller wheel on another shaft, on which is
located the clutch. This clutch consists of a disc having grooves in its
periphery to receive metal bands, one end of which is secured to a pro-
jection by means of a nut, by which the band may be tightened or
loosened at pleasure. The bands, of which there are two, extend around
the disc, and are attached at their opposite ends to the short arms of a
rock shaft, there being longer arms attached to the rock shaft, which
arms project inward on opposite sides of the hub. This hub is connected
to a collar which slides loosely on shaft, the hub being connected to the
collar in such a manner that while it is compelled to move with the
collar longitudinally on the shaft, it can move laterally independent of
A 2

page_text: the collar, the centre of the hub having an oblong hole cut in it for thất
purpose. The object of this lateral movement of the hub on the shaft
is to permit it to adjust itself to suit the position of the longer arms, as
they will vary according as one or the other of the belts may be more
or less tightened or loosened, and thus to bring the strain equally on
both belts. A lever is connected with the collar, by which it is moved
to and fro on the shaft, and as it is moved toward the disc the inclines
in the hub force the arms outward, thereby drawing the bands tight
around the disc. By this construction and arrangement of the parts
the operator is enabled to control the operation or movement of the
shovel in the most perfect manner, so that in case the shovel comes in
contact with a rock or any similar obstruction it can be instantly
released, and thus protected from injury, and at the same time by
the use of the long arms and the inclines for operating them great
power is obtained to tighten the bands, and thereby give motion to the
drum.
J
On the shaft of the wheel at the rear of the crane over which the
chain from the front of the shovel passes is mounted a sprocket wheel,
and on the shaft of wheel, on which is mounted the clutch last named,
is placed a similar sprocket wheel, and around these two sprocket wheels
passes an endless chain. By these means, when the chain is set in
motion, it communicates motion to the wheel, and thereby to the drum,
around which passes the chain that operates the shovel, and as, by means
of the clutch the shovel may be made to operate with the wheel or to be
thrown out of operation at pleasure, it is obvious that it can be con-
trolled in its movements at the will of the operator.
As in moving the machine the track or foundation is at all times liable
to be uneven it is necessary to have on the shaft of the first mentioned
drum a friction wheel arranged to be self-tightening, so that if the
machinery shall bind or not work freely and more power be required to
operate the said drum it may be had by the operation of the clutch
itself. In this case the two metal bands are used working on the
periphery of a wheel or disc, the same as in the case of the clutch
herein-before described, the bands being secured at one end by a nut so
as to be adjusted and the opposite ends being secured-to the short arm
of a rock shaft, the same as in the former case. The long arms of these
rock shafts rest against the face of a square block mounted on the same
shaft on which the wheel or disc is mounted.

page_text: It will be seen that if the wheel or disc commences to slip on the
shaft the projecting corners of the block coming in contact with the
long arms will press them outward, and thus cause the bands to be
drawn tighter and grip the wheel with increasing force.
In order that the power thus applied may be uniform, whichever way
the shaft revolves, the projections which strike the arms near their
outward end project further than the opposite corners, which strike the
arms further in, the relative projection of these points being so propor-
tioned that whichever of them operates the long arm it will be moved
the same distance, and consequently exert the same force on the bands.
By these means the clutch is made self-operating, and just in proportion
as more power is required to operate the drum, from whatever cause in
the same proportion will the bands be tightened on the wheel by the
operation of the block and the long arms of the rock shafts.
It should be understood that the bands will be drawn sufficiently tight
by means of the nut to hold the wheel in all ordinary cases, and that
hence the self-tightening devices will only come into play when extra
power is required on account of the cramping or binding of the parts,
as above described, or when the bands may have become loosened. The
block has attached to it a collar, around which a band passes, one end of
said band being secured to the frame of the machine and the opposite
end being secured to a lever operated by the foot of the attendant, so
that whenever desired the attendant, by simply pressing on the lever,
can tighten the rod and apply any desired force. The machine thus
constructed is mounted on car wheels, there being a pulley or wheel
secured to one of the axles by which motion is imparted to the machine
from the engine. These wheels are placed outside of the main frame
and arranged to run on a track which is constructed in sections. Two
or more of these wheels are provided with a radially projecting flange,
which is serrated or notched to afford means of readily turning the
wheels by levers when it is desired to move it but a little distance or the
engine fails to move it.
Another set of car wheels is also provided of larger diameter than the
aforesaid wheels, and placed at proper distances apart to run on an
ordinary railroad track. These wheels being of larger diameter than
the other wheels will so elevate the machine when placed on a railroad
track as to clear the smaller wheels from the rails and carry them over

page_text: cross tracks without hitting or touching any obstructions in the form of
rails, ties, frogs, or otherwise.
The Invention also consists in the peculiar construction and manner
of securing the main post on which the crane or swinging arm is
supported and moves.
It has been customary heretofore in constructing this class of machines
to make the main post of wood, thereby requiring frequent repairs and
replacement by new posts. This post according to the present Invention
is constructed of cast iron in the form of a tubular pillar or column. In
order to give it the requisite strength without rendering it too heavy it
is constructed with internal ribs or flanges. At the top it is cast with a
neck or shoulder to receive the collar which supports the crane and
permits it to turn on the post. The journal thus formed at the upper
end of the post is turned off smooth, and has a steel ring shrunk on to it
for the twofold purpose of giving it strength and preventing it from
breaking, and also to prevent the rapid wear at that point. The post
thus made is secured in position by means of a socket which rests on a
cross bar of the main frame and supported by truss rods.
A strong circular collar is bolted firmly to the cross bars above that
before mentioned, and has a hole of proper size to receive the post which
is slightly tapering from the top of the collar to its lower end so that it
will fit snugly in place and can be readily removed when desired.
At the point where the braces are connected to the post near its upper
end recesses are made in the post. The braces are provided with lugs
forged solid thereon of proper size to fill these recesses, so that when the
braces are bolted to the post the lugs receive the strain and thus unite
the post and braces firmly, and at the same time relieve the bolts from
the excessive strain which would otherwise be thrown upon them and
by which they were frequently broken as formerly used. The lower end
of the brace is attached to the side bars of the main frame by a stirrup
which passes entirely around the side bar. As these braces have to
receive a heavy downward thrust when the crane is swung around to
either side, and also a heavy upward strain when the crane is swung in
the opposite direction, and as this alternate pulling and thrusting soon
loosens or breaks the bolts by which the stirrup is secured to the frame,
the use of bolts is avoided by placing on the upper edge of the bar a
heavy metallic plate having a lug projecting from its upper face, and

page_text: the stirrup is then secured by means of a strong key which receives the
force of the downward thrust, and by means of which the stirrup can be
tightened up when necessary. By these means the strain is prevented
from being thrown upon the bolts which heretofore passed through the
stirrup and the bar, and the entire upward strain is transferred to the
under side of the bar where the stirrup has a broad flat bearing,
the downward strain or thrust being in like manner transferred to the
plate, which has a still larger bearing on the upper surface of the bar.
By these means the use of bolts to hold the stirrup in place is dispensed
with, the key, either alone or with a single bolt, amply sufficing for
that purpose. When bolts were used for this purpose the boring of
holes through the stirrup and the bar for their reception weakened those
parts, and this difficulty was greatly aggravated so far as the bar was
concerned by the alternate pulling and thrusting on them, which soon
caused them to wear large holes in the bar, the latter thereby being so
worn and weakened as soon to give way or break and thus render the
machine useless for the time being and necessitate the stoppage of its

page_text: inserted in a machine in place of a worn out or broken post, it being
understood of course that the posts with their sockets, collars, and
braces are so made as to fit any other machine of the same size or class.
Thus the necessity of sending a machine to the factory to be repaired
is obviated, as these parts can be sent wherever the machine may happen
to be and then be substituted for broken ones with but trifling delay.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Benjamin Joseph Barnard Mills in the Great
Seal Patent Office on the 6th November 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, BENJAMIN
JOSEPH BARNARD MILLS, of the Firm of Harris and Mills, of 23,
Southampton Buildings, in the County of Middlesex, Patent Agent,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixth day of May, in the year of our
Lord One thousand eight hundred and seventy-five, in the thirty-
eighth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Benjamin Joseph Barnard Mills, Her
special license that I, the said Benjamin Joseph Barnard Mills, my
executors, administrators, and assigns, or such others as I, the said
Benjamin Joseph Barnard Mills, my 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,"
(a communication to me from abroad by Oliver S. Chapman and John
Souther, both of Boston, in the State of Massachusetts, in the United
States of America,) upon the condition (amongst others) that I, the
said Benjamin Joseph Barnard Mills, my executors or administrators,
by an instrument in writing under my, or their, or one of their hands
and seals, 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

page_text: calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Benjamin Joseph Barnard Mills, 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, reference being had to the
Drawings hereunto annexed, and to the letters and figures marked
thereon, that is to say :-
The Invention consists in certain improvements in steam exavators,
which said improvements are herein-after described in detail.
Figure 1 is a side elevation of the machine; Figure 2 is a top plan
view with a portion removed; and Figures 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
13, 14, 15, and 16, are views of portions shown in detail.
In its general plan and construction the machine is similar to those
now in use, but as heretofore constructed these machines have been
liable to frequent breakage and disarrangement involving delays and
heavy expenses.
This Invention has for its object so perfecting the machine in its
details as to obviate these difficulties and at the same time render it
much more perfect in its operation.
In Figures 1 and 2, A represents the main frame on which are
mounted the machine and steam engine for operating it; B represents
the main post upon which the crane that carries the shovel is mounted;
this post is more fully described herein-after.
In Figure 2, K is the drum on which is wound the chain that swings
the crane to one or the other side as may be necessary to bring the
shovel to the required position, and this drum is operated by a gear
wheel F. As this must be put in motion at every movement of the
crane, and has to be thrown in and out of gear with the bevil gear on
shaft L at each movement, it is obvious that the strain caused by the
sudden throwing of it into gear so often will be very severe on the cogs,
and will have a tendency to break the said cogs. To remedy this the
wheel F is constructed as shown in Figures 11 and 12, the first being a.
front face view and the latter a transverse section on the line y, y, of
Figure 11. The main portion of the wheel consists of a disc having the
cogs cut on its face or periphery according as it is intended to be a spur
.

page_text: or bevil gear, and having four or more oblong openings made through it,
as shewn in Figure 11, with a recess in its rear face to receive the
disc F which is secured rigidly to the shaft m, the wheel F being loose
on the shaft. This disc F has on its face lugs e¹ which fit into the
openings in wheel F in such manner as to leave a space on the two sides
of the lugs e¹, which spaces are filled with rubber or other elastic
material as represented by i in Figure 11. A plate or cap t is then
placed over the face of the opening and secured by a screw, as shown in
Figure 12 which confines the rubber in place and firmly unites the two
parts F and F¹.
It will be readily seen that when the wheel F is thrown suddenly into
gear with another wheel which is in motion, the shock will expend itself
in a great measure upon the rubber springs i and thereby prevent the
cogs from being broken.
It has been customary to construct the crane C with cast-iron plates
at its outer end to receive and hold the end of the brace D, but these
plates are liable to break when subjected to the heavy work which the
machine is required to perform.
The side plates C₁ are according to the present Invention constructed
of wrought iron, as shewn in Figure 9, with a flange a* at the top, and
with strong cast-iron cheek pieces E bolted securely at the outer end,
thus forming a socket to receive and hold the upper end of the brace D
that will stand all the work and strain required of the machine.
These
The shovel E is made of metal and it is provided with heavy steel
prongs which project at the front, as shown in Figure 1.
prongs are intended to prevent injury to the shovel when brought into
contact with stones or other heavy objects, and also to hook under roots
or rocks that cannot be readily seized hold of by the shovel itself. It
has a door hinged so as to open and permit the contents of the shovel
to be emptied at ats rear end when its front end is elevated. In order to
permit this door F" to be raised far enough to be out of the way and yet
not strike against the bar O, it is suspended by the bent arms a and
hinged at a¹ on the upper side of the shovel some distance in front of
the rear end, as shown in Figure 1. The door is so cut away on its
upper side in order not to hit the bar O when opened that it is too
narrow to cover the entire rear end of the shovel, and to make up for
this deficiency a second and narrower door fis, hinged to the upper rear

page_text: end of the shovel in such a manner that when the main or outer door is
closed it will also shut over the inner door f and hold it closed.
Whenever the door F" is opened the door f is released and permitted
to swing free on its hinges, and by these means the shovel may be raised
at its front end sufficiently to empty it of its contents almost instantly,
and at the same time the door F" will swing entirely out of the
way.
For the purpose of having more complete control of the shovel a
novel style of clutch is employed for throwing the motive parts which
operate the shovel in and out of operation, these parts being shown in
Figures 3, 4, 5, 6, and 7. As usual the shovel is operated by a chain
wound around a drum A³ driven by a gear wheel A", which engages
with a smaller wheel on shaft A', on which latter is located the clutch as
shown in Figure 5. This clutch consists of a disc I, Figure 4, having
grooves in its periphery to receive metal bands b, one end of which is
secured to a projection c¹ by means of a nut by which the band may be
tightened or loosened at pleasure. The bands of which there are two
extend around the disc and are attached at their opposite ends to the
short arm c¹ of a rock shaft c, as shown in Figures 4 and 7, there being
longer arms & attached to the rock shaft c, which arms project inward
on opposite sides of the hub h, shown in section in Figure 6, and in plan
in Figure 3. This hub is connected to a collar e which slides loosely
on shaft A', the hub / being connected to the collar e, as shown in
Figure 3, in such manner that while it is compelled to move with the
collar longitudinally on the shaft A, it can move laterally independent
of the collar e, the centre of the hub & having an oblong hole cut in it
for that purpose, as shown in Figure 4. The object of this lateral move-
ment of the hub on the shaft is to permit it to adjust itself to suit the
position of the arms d as they will vary according as one or other of the
belts may be more or less tightened or loosened, and thus to bring
the strain equally on both belts b. A lever ex is connected with the
collar e by which it is moved to and fro on the shaft A, and as it is
moved toward the disc I the inclines e¹ in the hub h force the arms d
outward, thereby drawing the bands & tight around the disc I. By this
construction and arrangement of the parts the operator is enabled to
control the operation or movement of the shovel in the most perfect
manner, so that in case the shovel comes in contact with a rock or any
similar obstruction it can be instantly released and thus protected from

page_text: injury, and at the same time by the use of the long arms d and the
inclines for operating them, great power is obtained to tighten the bands
b and thereby give motion to the drum A³.
On the shaft of the wheel at the rear of the crane over which the
chain Y¹ passes is mounted a sprocket wheel w, as shown in Figure 1,
and on the shaft of wheel I on which is mounted the clutch last named
is placed a similar sprocket wheel w¹, and around these two sprocket
wheels passes an endless chain H*. By these means when the chain Y¹
is set in motion it communicates motion to the wheel I, and thereby to
the drum around which passed the chain that operates the shovel, and as
by means of the clutch the shovel may be made to operate with the
wheel w or be thrown out of operation at pleasure, it is obvious that it
can be controlled in its movements at the will of the operator.
As in moving the machine the track or foundation is at all times
liable to be uneven, it is necessary to have on the shaft of the drum Ķ a
friction wheel arranged to be self-tightening, so that if the machinery
shall bind or not work freely and more power be required to operate the
drum K, it may be had by the operation of the clutch itself. This
clutch is represented by N, in Figure 2, and its construction is shown in
detail in Figure 15. In this case the two metal bands are used working
on the periphery of the wheel or disc N, the same as in the case of the
clutch herein-before described, the bands v being secured at one end by
a nut so as to be adjusted, and the opposite ends being secured to the
short arm of a rock shaft c, the same as in the former case.
The long
arms d¹³ of these rock shafts rest against the face of a square block W
mounted on the same shaft Y on which the wheel or disc N is mounted,
as shown in Figure 15.
It will be seen that if the wheel N commences to slip on the shaft,
the projecting corners of the block W coming in contact with the arms
dwill press them outward, and thus cause the bands v to be drawn
tighter and grip the wheel N with increasing force.
In order that the power thus applied may be uniform whichever way
the shaft Y revolves, the projections o* which strike the arms d¹ near
their outward end project further than the opposite corners which strike
the arms further in, the relative projection of these points being so
proportioned that whichever of them operates the arm d', it will be
moved the same distance and consequently exert the same force on the

page_text: bands. By these means the clutch is made self-operating and just in
proportion, as more power is required to operate the drum from what-
ever cause, in the same proportion will the bands be tightened on the
wheel N by the operation of the block W and the arms of the rock
shaft c.
It should be understood that the bands will be drawn sufficiently
tight by means of the nut to hold the wheel in all ordinary cases, and
that hence the self-tightening devices will only come into play when
extra power is required on account of the cramping or binding of the
parts, as above described, or when the bands v may have become
loosened. The block W has attached to it a collar ¹ around which a
band w¹ passes, as represented in Figure 15, one end of said band being
secured to the frame of the machine at tx, and the opposite end y¹ being
secured to a lever operated by the foot of the attendant, so that when-
ever desired the attendant by simply pressing on the lever can tighten
the rod and apply any desired force. The machine thus constructed is
mounted on car wheels G, as shown in plan in Figure 13, there being a
pulley or wheel T secured to one of the axles, by which motion is
imparted to the machine from the engine. These wheels G are placed
outside of the main frame and arranged to run on a track which is con-
structed in sections, so that as fast as the machine is moved forward a
section of the track in the rear of the machine is taken up and laid in
front of the same. Two or more of these wheels are provided with a
radially projecting flange which is serrated or notched, as shown in
Figure 1, to afford means of readily turning the wheels by levers when
it is desired to move it but a little distance or the engine fails to
move it.
Another set of car wheels T is also provided of larger diameter than
the wheels G, and placed at proper distances apart to run on an ordinary
railroad track. These wheels T being of larger diameter than the
wheels G will so elevate the machine when placed on a railroad track as
to clear the wheels G from the rails and carry them over cross tracks
without hitting or touching any obstructions in the form of rails, ties,
frogs, or otherwise.
It has been customary heretofore in constructing this class of
machines to make the main post B of wood; and while the machine
were of a comparatively small size these wooden posts answered

page_text: tolerably well, though requiring frequent repairs and replacement by
new posts. Since the recent improvements in these machines, by which
their size and capacity have been greatly increased, the wooden posts
formerly used have proved insufficient, they enduring but for a few
weeks, necessitating frequent stoppages for repairs, and thus necessarily
putting a stop to all operations while waiting for the repairs to be
effected, thereby entailing much loss and expense. It is to remedy these
difficulties or objections that the following part of the present Invention
is devised. This post B is, according to the present Invention, con-
structed of cast iron in the form of a tubular pillar or column, as shown
in vertical section in Figure 8. In order to give to it the requisite
strength without rendering it too heavy, it is constructed with internal
ribs or flanges o¹, as shown in Figures 8 and 16. At the top it is cast
with a neck or shoulder to receive the collar which supports the cranc,
and permits it to turn on the post B. The journal thus formed at the
upper end of the post is turned off smooth, and has a steel ring ou
shrunk on to it for the twofold purpose of giving it strength and pre-
venting it from breaking, and also to prevent the rapid wear at that
point. The post thus made is secured in position by means of the
socket B which rests on the cross bar J of the main frame, and sup-
ported by truss rods p, as shown in Figure 8.
A strong circular collar B" is bolted firmly to the cross bars above J,
and has a hole of proper size to receive the post B, the post being
slightly tapering from the top of the collar B" to its lower end, so
that it will fit snugly in place and can be readily removed when
desired.
At the point where the braces C" are connected to the post B, near
its upper end; recesses are made in the post, as shown in section in
Figure 10, which is a cross section of the post taken on the line x, x, of
Figure 8.
The braces care provided with lugs forged solid thercon of
proper size to fill these recesses, so that when the braces are bolted to
the post the lugs receive the strain, and thus unite the post and braces
firmly and at the same time relieve the bolts from the excessive strain
which would otherwise be thrown upon them, and by which they were
frequently broken, as formerly used. The lower end of the brace C" is
attached to the side bars of the main frame by a stirrup S which passes
entirely around the side bar A, as shown in Figure 14. As these braces
have to receive a heavy downward thrust when the crane is swung

page_text: around to either side and also a heavy (upward strain when the crane is
swung in the opposite direction, and as this alternate pulling and
thrusting soon loosens or breaks the bolts by which the stirrup is secured
to the frame, the use of bolts is avoided by placing on the upper edge
of the bar A a heavy metallic plate P having a lug y projecting from its
upper face, as shown in Figure 14, and then securing the stirrup by
means of a strong key which receives the force of the downward
thrust, and by means of which the stirrup can be tightened up whenever
necessary. By these means the strain is prevented from being thrown
upon the bolts, which heretofore passed through the stirrup and the
bar A, and the entire upward strain is transferred to the under side of
the bar A, where the stirrup has a broad flat bearing, the downward
strain or thrust being in like manner transferred to the plate P, which
has a still larger bearing on the upper surface of the bar A. By these
means the use of bolts to hold the stirrup S in place is dispensed with,
the key, either alone or with a single bolt, amply sufficing for that
purpose. When bolts were used for this purpose the boring of holes
through the stirrup and the bar for their reception weakened those
parts, and this difficulty was greatly aggravated, so far as the bar was
concerned, by the alternate pulling and thrusting on them, which soon
caused them to wear large holes in the bar A, the latter being thereby
so worn and weakened as soon to give way or break, and thus render the
machine useless for the time being and necessitate the stoppage of its
use for repairs.
By the method herein described of securing the braces to the bar A
these difficulties are entirely obviated, and the machine is so improved
as to render it far more durable and serviceable.
As shown in Figure 1 the chain Y¹ which serves to raise and lower
the shovel E passes along on top of the crane C over a wheel on the same
shaft with the sprocket wheel w, thence down into the interior of the
post B, thence out through a slot I in the rear side of the post, under a
wheel or pulley B*, and down to the drum C* on the main frame of the
machine.
As the forming of the slot o³ through which the chain Y' passes
tends to weaken the post B at that point a flange or projection o³ is
formed around the edges of the slot on the outside of the post, as shown
in Figure 1, this projection also forming a bearing, to which the pulley B*
is secured.

page_text: Fifthly. An exavating machine having its platform or supporting
frame provided with two sets of wheels, the one set for operation on the
temporary track where the machine is to be used, and the other set of
larger diameter for conveying the machine from place to place on
ordinary railways, substantially as described.
Sixthly. The compound gear wheel, consisting of the moveable
portion F having the slots therein, and the disc F¹ with projections to
fit into said slots, with the rubber or other yielding material interposed,
the whole being arranged for joint operation substantially as shown and
described.
Seventhly. The combination of the clutch wheel I, constructed and
arranged as described, with the endless chain H*, and sprocket wheels w
and w¹, as set forth.
Eighthly. The combination of the wrought-iron plates E³, having the
flanges a formed thereon and the cast-iron cheek pieces E bolted
thereto with the crane C, substantially as herein shown and described.
Ninthly. The ribbed metallic post B, constructed substantially as
herein described, to adapt it for use in an excavating machine, as set
forth.
Tenthly. In combination with said post the socket B¹ and collar B",
when arranged to hold said post in position, substantially as herein
shown and described.
Eleventhly The combination of the stirrup S, plate P, and key 1,
with the bar A for securing the brace to the frame, substantially as
herein shown and described.
In witness whereof, I, the said Benjamin Joseph Barnard Mills,
have hereunto set my hand and seal, this Sixth day of November,
in the year of our Lord One thousand eight hundred and seventy-
five.
B. J. B. MILLS. (L.S.)