Year: 1897

page_text: I, THOMAS THOMSON, of 11, Provost Road, Haverstock Hill, London, N.W.
Civil Engineer, do hereby declare the nature of this invention to be as follows:-
My invention relates to an improved construction of excavator especially
designed for excavating tunnels. Owing to the difficulties presented by the
limited space at disposal, the presence of the shield at the face of the excavation,
and the variable nature of the material to be excavated, the mechanical apparatuses
at present employed for excavating purposes are unsuitable for tunnel work..
My invention provides a machine which whilst occupying a minimum of space
and that in such a manner as to allow of the access of the workmen and the com-
venient removal of the excavated material, will efficiently and automatically
excavate through the shield and deliver into waggons in the most convenien
manner.
My invention comprises the following principal parts:-
A dredger ladder of suitable size mounted on a swing frame which revolves on
a bottom frame. The aforesaid bottom frame spans the track laid in the tunnel
as wide as possible and leaving space for workmen and waggons to pass underneath.
The top swing frame is arranged to revolve on the bottom frame so as to enable
the dredger ladder to be slewed from side to side of the tunnel as requisite. The
dredger ladder is further supported by a projecting jib whereby it can be raised or
Jowered as desired. The top swing frame is continued backward to form a frame
for the gearing. The dredger is raised and lowered by a drum mechanism and
slewing may also be conveniently effected by means of a double drum. A third
similar mechanism moves chains which are led down the legs of the bottom frame
and secured to bolts in the tunnel for the purpose of holding down and moving the
apparatus and sustaining the weight and strain of the dredger. The bottom
tumbler of the dredger buckets is constructed with recesses in its ends and the
ladder beam crooked into these recesses so as to keep the bearings free from dirt.
The motive power for operating the machine at present contemplated is electricity,
but the apparatus may obviously be driven by other forces such as compressed air,
or water, or ropes and pulleys or other well known means.
The operation of the apparatus is as follows:-
The bucket ladder is projected into the face of the tunnel and the buckets scoop
out the material of the face and deliver the same at a sufficíent height and distance
from the face to fall into waggons placed beneath the apparatus. A line of rails
i conveniently laid within the rails on which the excavator stands for these
waggons. The top swinging frame on which the bucket ladder is pivoted is pre-
ferably so arranged upon the bottom frame as to be capable of revolving through
an angle of about 20 degrees. The revolving motion for the top tumbler of the
bucket ladder is capable of being disconnected at will so that the other motions of
the machine may take place without working the bucket ladder. The motion of
the machine along the rails I prefer to effect by means of a double barrel and

page_text: leading chains from the same through the top of the bottom frame down the legs
and leading forward and backward. The ends of these chains are suitably attached
to bolt holes in the tunnel ironwork. The machine can then be easily moved back-
wards or forwards by winding on these chains. The other motions of the gearing
are preferably effected by means of worm gear but can also be arranged for mitre
gear or the like. The bucket ladder is required to occupy a minimum space in
order to efficiently get into the corners of the shield face. The tumblers are
preferably seven-sided for smoothness of working, and the buckets should be a
least five inches deep. The bottom tumbler is so constructed that the cutting path
of the outside edge of the bucket is clear of the ladder or beam, this beam is then
crooked out to hold the rollers. The bearings of the bottom tumbler should be
enclosed to keep out dirt.
In order to efficiently excavate the face close to the shield where the buckets
cannot reach, I provide on each side of the bottom tumbler a shaft provided with
vanes or blades, and with suitable gearing for transmitting motion from the
tumbler shaft. These revolving shafts and blades excavate the material close up
to the shield and deliver it within the reach of the buckets.
I prefer to construct the shaft for the bottom tumbler as a fixture and put brass.
sleeves inside the tumbler, the ton tumbler being driven by the gearing must have"
its shaft fixed in the tumbler. The central pivot of the mechanism may be formed
of a solid wrought iron ring post fixed to a casting in the swing frame and revolving
in bearings at top and bottom. Or it may be constructed as a centre pin in tension
only and the front weight be supported on rollers or a lubricated slide according
to the circumstances of the work to be done. If necessary the apparatus may be
counterbalanced to relieve the strain on the centre pin.
The precise details of the construction given above are those found suitable in
the experiments which I have conducted, but I do not limit myself to the precise
mechanical details given.
Dated this 19th dow T
100%
W. P. THOMPSON & Co.
Patent Agents for the Applicant, 322, High Holborn, London, W.C.
Improvements in or relating to Excavators."
I, THOMAS THOMSON, of 11, Provost Road, Haverstock Hill, London, N.W.,
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:-
My invention relates to an improved construction of excavator especially
designed for excavating tunnels. Owing to the difficulties presented by the
limited space at disposal, the presence of the shield at the face of the excavation,
and the variable nature of the material to be excavated, the mechanical apparatuses
at present employed for excavating purposes are unsuited for tunnel work.
My invention provides a machine which whilst occupying a minimum of space
and that in such a manner as to allow of the access of the workmen and the cou-
venient removal of the excavated material, will efficiently and automatically
excavate through the shield and deliver into waggons in the most convenient
manner.
My invention comprises the following principal parts:-
A dredger ladder of suitable size mounted on a swing frame which receives en
a bottom frame. The aforesaid bottom frame spans the track laid in the tunnel

page_text: pass
as widely as possible and leaves space for workmen and waggons to
The top swing frame is arranged to revolve on the bottom frame so as to enable
underneath.
the dredger ladder to be slewed from side to side of the tunnel as requisite. The
dredger ladder is further supported by a projecting jib whereby it can be raised or
lowered as desired. The top swing frame is continued backward to form a frame
for the gearing. The dredger is raised and lowered by a drum mechanism and
slewing may also be conveniently effected by means of a double drum. A third
similar mechanism moves chains which are led down the legs of the bottom frame
and secured to bolts in the tunnel for the purpose of holding down the
apparatus and sustaining the weight and strain of the dredger. The bottom
tumbler of the dredger buckets is constructed with recesses in its ends and the
ladder beam crooked into these recesses so as to keep the bearings free from dirt.
The motive power for operating the machine at present contemplated is electricity,
but the apparatus may obviously be driven by other forces such as compressed air,
or water, or ropes and pulleys or other well known means.
The operation of the apparatus is as follows:
The bucket ladder is projected into the face of the tunnel and the buckets scoop
out the material of the face and deliver the same at a sufficient height and distance
from the face to fall into waggons placed beneath the apparatus.
A line of rails
is conveniently laid within the rails on which the excavator stands for these
waggons. The top swinging frame on which the bucket ladder is pivoted is pre-
ferably so arranged upon the bottom frame as to be capable of revolving through
an angle of about 20 degrees. The revolving motion for the top tumbler of the
bucket ladder is capable of being disconnected at will so that the other motions of
the machine may take place without working the bucket ladder. The motion of
the machine along the rails I prefer to effect by means of a double barrel and
leading chains from the same through the top of the bottom frame down the legs
and leading forward's and backward. The ends of these chains are suitably attached.
to bolt holes in the tunnel ironwork. The machine can then easily be move back-
wards or fowards by winding on these chains. The other motions of the geari
are preferably effected by means of worm gear but can also be arranged for mitre
gear or the like. The bucket ladder is required to occupy a minimum space in
order to efficiently get into the corners of the shield face. The tumblers are
preferably seven-sided for smoothness of working, and the buckets should be at
least five inches deep. The bottom tumbler is so constructed that the outting path
of the outside edge of the bucket is clear of the ladder or beam, this beam is then
crooked out to hold the rollers. The bearings. of the bottom tumbler should be
enclosed to keen out dirt.
I prefer to construct the shaft for the bottom tumbler as a fixture and put brass
sleeves inside the tumbler, the top tumbler being driven by the gearing must have
its shaft fixed in the tumbler. The central pivot of the mechanism may be formed
of a solid wrought iron ring post fixed to a casting in the swing frame and revolving
in bearings at top and bottom. Or it may be constructed as a centre pin in tension
only and the front weight be supported on rollers or a lubricated slide according
to the circumstances of the work to be done. If necessary the apparatus may be
counterbalanced to relieve the strain on the centre pin.
Referring to the accompanying drawings
Figure 1 is a side elevation of the excavator.
Figure 2 is a plan, and
Figure 3 is a section taken on the line, Figure 2.
Figure 4 is a section, and
Figure 5 is a plan of the buckets to be described.
The bucket ladder P of suitable size is mounted upon a swinging frame T which
revolves upon a bottom frame T2. The aforesaid bottom frame T spans a track
laid in the tunnel as wide as possible leaving a space T3 for the passage of the men,
and trucks to pass underneath, as shewn in Figure 3. The top swinging frame T
is arranged to revolve on the bottom frame T2 so as to enable the bucket ladder P
i iz

page_text: to be slewed from side to side of the tunnel as required
further supported by chains connected to the jib 14 whereby it can be raised or
lowered as desired; the top swinging frame T is continued back to form a frame
for the gearing to be hereinafter described.
The apparatus is capable of four fold motion as follows:-
(1) Raising and lowering the bucket ladder P.
(2) Slewing.
(3) Forward and backward movement of excavator.
(4) Revolving motion of the top tumbler of bucket ladder.
1. The bucket ladder is raised and lowered by the chains N N secured at one
end to the drum I and having their other ends passed over a chain pulley 01
supported in suitable bearings in the jib T, and thence around another chain
pulley 03 also suitably fixed to the bucket ladder P. From the lower chain
heel 03 the chain N passes upwards and is securely fixed at 03 to the jib T
The power requisite for driving the drum I is obtained from the motor which is
contained in the box A. Upon the armature shaft A¹ is secured a worm B which
gears with a worm wheel C and drives the main shaft D) which runs in suitable
bearings longitudinally in the top swinging frame. Upon the shaft D) is also
mounted a pair of bevel wheels H and H' running loosely which engage with a
third bevel wheel G+ mounted upon a vertical shaft G3 also provided with suitable
bearings. To the shaft is secured a worm G engaging with a worm wheel E,
mounted on a shaft E¹ which drives the drum. I. The bevel wheels H H¹ are
In this
thrown in or out of gear by cone clutches H2 H3 keyed upon the shaft 1).
way the requisite control is obtained for raising and lowering the bucket ladder P.
It will be clearly seen that when both the friction clutches H H are thrown out
of engagement with their respective bevel wheels no motion will be transmitted
to the drum shaft E and the friction of the worm wheel E against the worm G
will be found sufficient to prevent the movement of the drum I, thus retaining the
bucket ladder in position. Suitable mechanism is provided but not shewn in the
drawing for controlling the cone clutches.
2. The bucket ladder is slewed to and fro by means of a chain which passes over
a pulley S⁹ fixed upon a shaft S8 secured in bearings on the frame. The chain
after passing over the pulley S passes down under pulleys S1 S1 on either side
to the sides of the under framing T2 where it is suitably secured to the under
frame at S13 S13. The motion of the shaft S8 is derived from a worm wheel S7
which engages with a worm S6 secured to a shaft S5 upon the end of which shaft
is arranged a bevel wheel S also engaging with wheels S S¹ revolving loosely
the main shaft D which main shaft is revolved by the
wheel C engaging with worm B mounted upon the armature shaft A
In order to obtain the slewing motion in either direction cone clutches S2 and S3
are mounted upon sliding keys upon the shaft D to alternately engage with their
respective bevel wheels S S¹.
upon
worm'
Suitable mechanism (not shown) is also employed to operate the cone
clutches S S³. In this case it will also be seen that the top framing is held in
position when the same clutches are both out of engagement with their respective
bevel wheels by the friction of the worm S6 in engagement with the worm $7.
3. The necessary forward and backward motion of the excavator along the rails
is obtained by means of the rotating end A2 of the armature shaft which has
fixed upon it a belt pulley Q. From said pulley a band passes round another
larger pulley Q2 mounted upon a shaft Q3. The shaft Q3 is provided with suitable
bearings Q Q arranged upon the circular casting T which forms the pivot for
the upper part T of the excavator when the dredger ladder P is being slewed.
The shaft Q has mounted loosely upon it a pair of bevel wheels Q and Q which
also engage with another bevel wheel Q8 which transmits motion to a vertical
shaft R¹ passing down through bearings in the pivotal portion of the framing T
of the excavator as shewn in Figure 2 and 3. At the lower end of the vertical
shaft R' is secured a worm R which engages with a worm wheel R² mounted on

page_text: Upon
a shaft. R which passes underneath through the lower part of the excavator.
the ends of the shaft R³ are secured chain pulleys R R round which passes
chains R R and the ends of which are firmly secured to bolt holes in front and
behind the apparatus and on either side thereof to the tunnel ironwork. The
necessary forward and backward movement is obtained by friction cones keyed
upon the shaft Q to throw in and out of gear the bevel wheels Q and Q³ which
transmit motion to the shaft R₁ through bevel wheel Q8. The clutches are thrown
in and out of action by gearing situated at any convenient position for the
operator. The excavator is held firmly in position by the fretion of the worm R
upon the worm wheel R'.
4. The main shaft 1) transmits a rotary motion to the shaft L through the
bevel wheel K. Upon the shaft L is keyed the hexagonal bucket chain pulley M
and tumbler block P2 over which the endless chain P with buckets 1 passes
to the excavating end of the bucket ladder. The requisite amount of tension is
given to the bucket chain by means of the tension screws P3 and tightening
bolts P. The tension device also allows the bucket chain to be slackened for
repairs.
.
In order to prevent the bucket chain from being broken when undue strain is
thrown upon it a special frictional slipping clutch D is provided mounted upon
the main shaft D and held to its work against the normal resistance by a powerful
spring 3 (Figures 1 and 2), the necessary adjustment being made by the tightening
nuts 12. By this means when any undue strain comes upon the bucket chain
exceeding that of the pressure exerted by the compression of the spring 1³ the
clutch is allowed to slip, and injury to the working parts thus prevented.
The dredger buckets shewn in Figures 4 and 5 are constructed with sides P6,
bottom P5, and back P7 The cutting teeth P8 are secured to the back P7. Along
the bottom of the bucket extend webs P with holes p10 110 through which pass
bolts to secure the the separating link P", Figure 1.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:-
The improved excavator constructed and operating substantially as described
with reference to the accompanying drawings.
Dated the 12th day of OctobU FOST
W. P. THOMPSON & Co.
Patent Agents for the Applicant
Of London, Liverpool. Manchester and Birmingham.