IMPROVEMENTS IN TUNNELLING MACHINERY
Year: 1880

page_text: LETTERS PATENT to Thomas English, of Hawley, near Dartford, in the
County of Kent, for an Invention of "IMPROVEMENTS IN TUNNELLING
MACHINERY."
PROVISIONAL SPECIFICATION left by the said Thomas English at the Office
of the Commissioners of Patents on the 25th October 1880.
THOMAS ENGLISH, of Hawley, near Dartford, in the County of Kent.
'IMPROVEMENTS IN TUNNELLING MACHINERY."
In the Specification of a Patent granted to F. E. B. Beaumont on the 2nd day
of December 1875, No. 4166, was described machinery for cutting cylindrical
tunnels in soft rock by cutters arranged step-wise on a head made to revolve and
advance. My Invention relates to improvements in machinery of this class, having
chiefly for their object means for mounting firmly the revolving head, and of
effecting its step by step advance as the excavation proceeds. The main framing
of a tunnelling machine, according to my Invention, consists of two parts. The
under frame or bed is of trough like form, fitting the lower part of the circular
tunnel, and having at its upper edges suitable guides parallel to the axis of the
tunnel, along which the upper part of the framing is fitted to slide longitudinally.
On the upper frame the axis of the boring head is mounted in bearings with gearing
and an engine worked by compressed air so as to cause the boring head to revolve
slowly. The axis of the boring head extending backwards is made tubular and
fitted with a piston, the rod of which projects backwards and is fixed at its end
to the under frame or bed. The air engine works hydraulic pumps whose throw
can be varied at will, forcing water into the hollow axis of the boring head through
a channel provided within the piston rod, and thus causing it to advance while it
revolves. When it has advanced as far as the length of the guides permits, the
gearing by which it is revolved is disconnected from the engine, its axis is relieved
from the hydraulic pressure, and by means of four hydraulic jacks projecting down
from the upper framing and made to bear against the lower part of the tunnel, the
whole machine is slightly raised. The water under pressure is then admitted into
the annular space round the piston rod, and while the upper frame remains stationary

page_text: the under frame or bed is caused to advance under it, after which the lifting
jacks being relieved from pressure allow the bed to take its bearing in its advanced
position, which may be either parallel or inclined to its previous one, and the boring
head is again put in motion forwards, Instead of hydraulic jacks bydraulic
pressos supplied by the engine pumps may be used. Thus the cutting of the tunnel
is advanced step by step, each step being the length of travel of the one frame along
the other. Instead of employing hydraulic pressure for effecting the advance of
the machine as above described, a screw on the axis of the head may be engaged
with a fixed nut on the under frame, and caused to revolve in the one direction or
the other according as the one frame or the other is being advanced. Also screw
jacks may be employed for raising the machine, and the bed may be held securely
in position by screw jacks bearing against the top or sides of the tunnel. According
to one arrangement which I employ for this purpose two bars bent to fit the interior
of the tunnel are hinged one at each side of the bed, and their upper ends are
connected by a screw coupling, by turning which in the one direction or the other
the bent bars can be strained firmly against the sides of the tunnel so as to hold
securely the bed to which they are jointed, or they can be slackened back to allow
of the advance of the bed. The boring head consists of two strong radial arms
projecting in opposite directions from the axis, each arin baving through it a
number of cylindrical holes to receive tool holders which are clamped therein by
keys, and any of which can be withdrawn backwards for the purpose of repairing
or replacing their tools. I arrange the cutting tools so as to cut concentric annular
chases in the face of the rock, leaving between them narrow portions of the material
which can be readily broken away, or which crumble away while the machine is at
work. Within the trough hollow of the bed I arrange inclined worms which
cause the excavated material to travel backwards and upwards so that it is delivered
behind the machine into trucks, by which it is removed from the tunnel.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Thomas English in the Great Seal Patent Office on the 23rd April
1881.
THOMAS ENGLISH, of Hawley, near Dartford, in the County of Kent.
"IMPROVEMENTS IN TUNNELLING MACHINERY."
In the Specification of a Patent granted to F. E. B. Beaumont on the 2nd day of
December 1875, No. 4166, was described machinery for cutting cylindrical tunnels
in soft rock by cutters arranged on a head made to revolve and advance. My
Invention relates to improvements in machinery of this class, having chiefly for their
object means of mounting firmly the revolving head, and of effecting its step by
step advance as the excavation proceeds. For this purpose I construct the tunnelling
machine as shewn in the accompanying Drawings. Fig. 1 is a longitudinal section;
Fig. 2 is a plan; Fig. 3 is a transverse section on the line Z, Z, and Fig. 4 is an
end view. A is an underframe or bed of trough like form curved on its under side
to fit the circular section of the tunnel. Within the hollow of the bed are accom-
modated travelling chains of buckets a which receive the excavated material and
convey it backwards and upwards to the hinder part of the machine, where they
deliver it into trucks at a¹. On the upper edges of the bed A is fitted to slide the
upper frame B, which carries the machinery, and which is prevented from rising
from the bed A by hook guides b that catch under the flanges at the edges of A.
On the frame B are fixed the cylinders C of an engine worked by compressed air
conveyed to them by a pipe laid along the tunnel from suitable air compressing
apparatus outside. The pistons of the cylinders C work a crank shaft c, which
through intermediate gearing c¹ gives slow rotation to the central shaft D, which
carries the boring head at its front end. The crank shaft also by means of a crank
pin e works a hydraulic pump E, the throw of the crank pin e being made
adjustable, so that the stroke of the pump can be varied as a greater or less delivery
of water is required. The shaft D is tubular, and its interior forms a hydraulic
cylinder which is fitted with a piston d having a rod d¹ consisting of an inner
and an outer tube. The inner tube opens into the space beyond the piston; the
outer tube by lateral openings communicates with the annular space of the cylinder.
These tubes pass together through a stuffing box at the back end of the tubular
shaft D, and are firmly secured to a bracket a projecting up from the bed A. At
the end of the tubular piston rod is a valve box which communicates by jointed
pipes e¹ with the pump E. By means of suitable valves in the valve box d² the
water pressure can be directed through the double tubular piston rod either
into the space beyond the piston d or into the annular space surrounding the piston
rod. In the former case the piston being attached to the bed A, which is stationary,
the shaft D with its boring head, and with the whole of the upper frame B carrying
the engines and gearing, is pressed slowly forwards while the boring head revolves,
cutting its way into the face of the rock. When the upper frame has thus been
advanced a certain distance the machinery is stopped, the shaft D and boring
head D', and the upper frame B, with all that it carries, is then raised a little by
means of a jack F, which is jointed to the boring head, and two jacks F', F', which
are jointed to the hinder part of the upper frame. The bed A is also thus raised a
little, being suspended from the upper frame so as to be just clear of the ground,
and the valves at d² are inoved so that the water under pressure is made to act on
the annular area of the piston d, and thus the bed A is caused to advance while the
upper frame remains stationary. When the bed A has thus been advanced, the
jacks F, F¹, are worked so as to lower the upper frame and bed in the advanced
position, and the boring is resumed. Should it be required to alter the direction or

page_text: level of the tunnel, wedges or packings can be placed under the bed A at either
side or at either end of it when it is in its raised position, so that when it is again
lowered on such wedges or packings it will take a slightly altered attitude, directing
the line of bore a little towards the one side or the other, or a little upwards or
downwards, as the case may be. I also attach to the front part of the bed A an
angle iron ring K carrying set screws k, by screwing which against the interior
surface of the tunnel the machine is steadied in the desired position whilst at work.
Although I have shewn in the Drawings the jacks F, F', as being screw jacks, they
might be hydraulic jacks worked by water pressure from the pump E or from an
accumulator charged by it. The boring head consists of two strong arms G pro-
jecting from a boss fixed on the shaft D. These arms carry cutters y suited to the
rock which has to be bored. For comparatively soft rock, such as chalk, a single
chisel edged bar extending radially along the face of each arm will generally
suffice; but for harder rock, separate chisels g are employed, those on the one arm
being arranged so as to cut in the annular spaces left by those of the other arm.
Each of the arms G has its hinder side hollowed out in trough like form, as shewn
at g', the hollow having a sloping mouth directed backwards so as to shoot debris
of the borings into the buckets a. There is room provided for workmen to stand
on gratings H to watch the working and to shovel debris into the buckets. The
chains of buckets are driven by the pullies a² on a shaft mounted at the hinder end
of the upper frame B, that shaft being driven by a chain a³ worked by bevil
gearing a from the crank shaft c. Although I have described the application of
hydraulic pressure to advance the machine a screw might be employed for that
purpose.
Having thus described the nature of my Invention, and in what manner the
same is to be performed, I hereby declare that I make no general claim to the
boring of a circular tunnel by means of a boring head, carrying cutters caused to
revolve and advance, but I claim in respect of tunnelling machinery of that
kind,
First. Constructing the framing of the apparatus in two parts, a bed and an
upper framing, the one fitted to slide longitudinally along the other, so that the
apparatus can be advanced step by step as the boring proceeds, substantially as
herein described.
Second. Advancing the boring head and upper frame while the bed is stationary,
and advancing the bed while the upper frame is stationary, by hydraulic pressure
acting on a piston fitted to work within the tubular shaft of the boring head,
substantially as herein described.
In witness whereof, I, the said Thomas English, have hereunto set my hand
and scal, this Twentieth day of April, in the year of our Lord One
thousand eight hundred and cighty one.
THOS ENGLISH
Gal