IMPROVEMENTS IN MACHINES FOR CUTTING COAL AND OTHER HARD SUBSTANCES
Year: 1878

page_text: LETTERS PATENT to Johan Richard Schram, of Norfolk Street, Strand, in the
County of Middlesex, Engineer, for the Invention of "IMPROVEMENTS IN
MACHINES FOR CUTTING COAL AND OTHER HARD SUBSTANCES."
PROVISIONAL SPECIFICATION left by the said Johan Richard Schram at the
Office of the Commissioners of Patents on the 23rd September 1878.
JOHAN RICHARD SCHRAM, of Norfolk Street, Strand, in the County of Middlesex,
Engineer. "IMPROVEMENTS IN MACHINES FOR CUTTING COAL AND OTHER HARD
SUBSTANCES."
The coal-cutting machine constructed according to this Invention is intended to
be worked by steam or compressed air, the cutting tool obtaining the necessary per-
cussive action therefrom. The shifting of the position of the cutting tool is effected
by hand, and the whole apparatus is mounted on a carriage which can be moved
forward on rails by means of a chain and drum or by other suitable means. On
the track or carriage I mount in bearings a vertical fulcrum spindle or weigh shaft,
on which is fixed a lever which can be shifted or moved by hand round its fulcrum.
The outer end of this lever is made forked, or suitable for receiving a cylinder fitted
with a piston provided with a cutting tool receiving a percussive action. The
cylinder and tool are about at right angles with the lever, but the position of the
cylinder may be adjusted somewhat by slot holes and screws or other means for
giving the desired angle. This cylinder is by preference fitted with a double piston
and with piston slide valves, all arranged as described in the Specification of my
Patent dated 11th January 1876, No. 119. The weight of lever cylinder and tool
is counterbalanced. The cylinder may be made adjustable in its length direction on
the lever.
The cutting tool is by preference arranged as a system of teeth to operate in a
similar way as the pick in the hands of the miner. The teeth or points are placed
in rows, and by preference with one long tooth in the middle and two or more pairs

page_text: of shorter teeth in front and behind. The teeth may be made separate, to take out
and change when blunt or damaged.
The lever is shifted round its fulcrum by means of a handle and suitable gear,
say worm and worm wheel.
The machine can be made to work left or right by simply turning the cylinder
with tool end for end on the lever.
Although I prefer to shift the tool and the whole apparatus by hand, as described,
these movements may if desired be effected automatically.
For stone cutting I suspend the cylinder with cutting tool on a cross bar united
to two uprights or standard frames, and I mount over the cylinder a rack which is
also connected to the two uprights. By means of a handle and of a pinion fitted
on the cylinder and gearing into the rack I move the cylinder as required.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Johan Richard Schram in the Great Seal Patent Office on the
22nd March 1879.
JOHAN RICHARD SCHRAM, of Norfolk Street, Strand, in the County of Middlesex,
Engineer. "IMPROVEMENTS IN MACHINES FOR CUTTING COAL AND OTHER HARD
SUBSTANCES."
The coal-cutting machine constructed according to this Invention is intended to
be worked by steam or compressed air, the cutting tool obtaining the necessary per-
cussive action therefrom. The shifting of the position of the cutting tool is effected
by hand, and the whole apparatus is mounted on a carriage which can be moved
forward on rails laid along the side of the wall of coal which it is desired to "hole"
by means of a chain and drum or by other suitable means. On the truck or carriago
I mount in bearings a vertical fulcrum spindle or weigh shaft, on which is fixed a
lever provided with handles by means of which it can be shifted or moved by hand
round its fulcrum. The outer end of this lever is made forked or suitable for.
receiving a cylinder fitted with a piston provided with a cutting tool receiving a
percussive action. The cylinder and tool are about at right angles with the lever,
but the position of the cylinder may be adjusted somewhat by slot holes and screws
or other means for giving the desired angle. This cylinder is fitted with suitable
piston, and with self-acting valve or valves for distributing the steam or compressed
air or other impelling fluid, so as to produce the required percussive action.
A con-
venient mode of carrying this part of my Invention into effect is by the use of a
double piston, and with piston slide valves arranged like or similar to those described
in the Specification of my Patent dated 11th January 1876, No. 119.
The weight
of lever cylinder and tool is counterbalanced. The cylinder may if desired bo mado
adjustable in its length direction on the lever.
The cutting tool is by preference arranged as a system of teeth to operate in a
similar way as the pick in the hands of the miner. The teeth or points are placed
in rows, and by preference with one long tooth in the middle and two or more pairs
of shorter teeth in front and behind. The teeth may be made separate, to take out
and change when blunt or damaged.
The machine can be made to work left or right by simply turning the cylinder
with tool end for end on the lever.
Although I prefer to shift the tool and the whole apparatus by hand, as described,,
these movements may if desired be effected automatically.
For stone cutting I suspend the cylinder with cutting tool on a cross bar united
to two uprights or standard frames, and I mount over the cylinder a rack which is
also connected to the two uprights. By means of a handle and of a pinion fitted
on the cylinder and gearing into the rack I move the cylinder as required.
On the accompanying Sheet of Drawings I have shown a coal-cutting machine
constructed according to this my Invention, and in which the cutting tool impelled
by compressed air is impelled at the rate of 400 to 1000 strokes a minute.
Figure 1 is a plan of the whole machine.
Figure 2 is a side elevation of the same.
Figure 3 is a longitudinal vertical section of the percussive engine.
Figure 4 is a vertical cross section of the percussive engine.
Figure 5 is an end view, and Figure 50 a side view of the cutting tool.
Figure 6 is a side view of a cutting tool with changeable teeth.
Figure 7 is a cross section of the cut in the coal.
In Figures 1 and 2 A is the body of the carriage, which is built with 4 wheels to
run on rails; B is a massive arm or lever working on a pivot C placed in the centre
of the upper surface of the body of the carriage; D is the percussive engine bolted

page_text: on to one end of the arm or lever; E, E, are the handles at the other end of the
arm or lever by which it is turned on its pivot; F is the drum round which the
flexible tubing for conveying motive fluid to the percussive engine is coiled; G is
the drum round which the feed chain H is passed; I, I, are handles for turning the
drum G by means of worms and worm wheels, as shewn. These handles are placed
one on each side of the drum G, as the machine is constructed to cut a groove on
either side, and as only one worm gear is used at one time the other must be
thrown out of gear. K is the flexible hose leading from the hollow axis of the
drum F (which is there formed with an air-tight joint) to the percussive engine D.
By connecting the hose K to a joint which can freely turn in or on the hollow axis
of the drum F the said drum is free to turn as required. L is the starting cock;
N is the cutting tool fixed in the piston rod of the engine.
When the machine is started by admitting the compressed air by the cock L, tho
cutting tool N begins to strike against the coal, which it chips away. A miner at the
side of the machine gradually moves the arm B backwards and forwards by means of
the handles E, thus causing the lever B, with percussive engine D and tool N, to move
in an are round the fulcrum C. The dotted lines indicate the position of lever B with
cutting tool N at the extreme end of arc, stroke, or sweep. As the coal is thus
chipped away by the repeated action of the cutting tool N in the piston rod of tho
engine moved in the manner described, the carriage A with the whole machine or
apparatus is simultaneously moved forward by another miner, who has also charge
of the cock L, by turning one of the handles I, which by means of a worm gear,
shown, rotates the drum G, round which is passed the chain H, the further end of
which is fixed at some point in advance of the machine. As the chain H winds
rounds the drum G the whole apparatus is hauled forward, and at the same time
the groove is extended in the direction of the arrow. This action is continued until
the apparatus arrives to the point where the forward end of the chain is fixed; the
chain may then be refixed further in advance, and the groove extended in a similar
manner.
As the groove is cut, should the percussive action of the cutting tool be insufficient
to keep the groove clear of coal dust, one of the miners may from time to time
scrape it out with the scraper O.
As the angle at which the cutting tool strikes the coal with the best effect varies
in different sorts of coal, the holes at P for the bolts by which the percussive
engine D is attached to the arm B are made large enough to admit of the angle
between the arm and the cutting tool being adjusted.
The engine may be bolted on to the arm with the piston rod on either side of the
carriage so as to undercut either a right-hand or a left-hand seam of coal.
In Figures 3 and 4, representing the percussive engine constructed somewhat
similar to the rock drill cylinder of my aforesaid former Patent, a is the inlet for
the motive fluid; b is the piston valve, which consists of a hollow cylinder provided
with parts at d, d, and with packing springs at bl.
The ends of this piston valve are solid and of smaller diameter than the hollow
portion. The solid ends fit exactly in cylindrical recesses 1, 11, at each end of the
piston valve box, the edges of which recesses are bevelled to receive corresponding
bevelled faces where the diameter of the piston valve is increased. K, K¹, K², are
the outlets for the compressed air or motive fluid.
The main piston c is double, that is, it has packing springs c' and bearing surfaces
in two places at some distance apart, as shewn, the intervening space at c being
smaller in diameter. It is made in one piece with its rod c, which passes out
through a stuffing box at the lower cylinder cover; its outer end carries the cutting
tool. The piston is kept from rotating by means of two round guides m screwed
into the back or upper cylinder cover, and fitting loosely into suitable recesses in
the piston so as not to diminish the piston surface, as shown.
When the engine is in the position shewn in Figure 3, the motive fluid being

page_text: admitted through the inlet a fills the hollow space in the piston valve b, which
space serves the purpose of a steam chest in an ordinary steam engine. From here
the motive fluid enters directly into the main cylinder e through the ports d, d', in
the piston valve and the cylinder respectively. At this time the lower end of the
main cylinder e' is in free communication with the outlet K by means of the port d³
Thus the
and the hollow space round the small end of the piston valve, as shewn.
compressed air in cylinder e acts effectively on the whole of the upper surface
of the main piston and forces it downwards, producing the forward stroke of the
engine.
When that portion of the main piston at c¹ has passed the port the motive
fluid rushes through that port into the cylinder in the piston valve box. As at
this moment the cylinder at the other end of the piston valve box is in communi-
cation with the outlet K' by means of the port f' and the hollow space round the
main piston at c, the motive fluid filling. the cylinder forces the piston valve b
downwards, so that the port d comes over the port d³, and the port d' is shut off
from communication with the hollow space in the piston valvo, and because of the
smaller diameter of the end of the piston valve it affords communication between
cylinder e at outlet K'.
The motive fluid now rushes from the hollow space in the piston valve b through
the ports d², d, into the lower end of the main cylinder c', where it acts effectively
As soon as
on the lower surface of the main piston, causing the backward stroke.
that part of the lower piston at c¹ has passed the port f¹ the motive fluid rushes
through that opening into cylinder 1, causing it to return into the position shewn
in Figure 3 (the cylinder being in communication with the outlet K¹ through the
port and the hollow at c).
The piston valve is kept from rotating by means of set screws o, the ends of
which serving as guides project into longitudinal grooves in the casting of the piston
valve, as shewn.
At h are shewn the bolts for attaching the engine to the arm B of the carriage.
These bolts h pass through the slot holes P, shewn at Figure 1. p is a screw bolt
for fixing the cutting tool in a slot in the end of the piston rod. The cutting tool
has projecting lugs v, Figures 1 and 3, which embrace the piston rod beyond the
depth of the slot, and is firmly secured to the piston rod.
This construction I also use for rock drills and other reciprocating engines.
The cutting tool shewn at Figures 5 and 5a bas a system of teeth, as shewn, con-
structed to produce a similar effect as a pick in the hands of a miner, with this
difference, that this tool has nine teeth (more or less), whilst a pick has but one.
The effect of the tool is shewn in Figure 7, which is a section of the cut in the
coal. Figure 6 shows a cutting tool with movable teeth, the advantage of which
construction is that any one tooth may be exchanged when blunt or broken without
sending the entire cutting tool out of the mine. The heads of the teeth are turned
conical to fit into corresponding conical holes in the main part of the cutting tool.
Transverse drift holes are made through these conical holes at their bottoms, and
the heads of the teeth are not made long enough to reach the bottoms of the conical
holes, so that the teeth can be driven out by a drift when desired. When the per-
cussive engine is constructed as described in my Patent Specification No. 119, 11th
January 1876, "Rock-Boring Machines," the round guides m before described for
preventing the rotation of the main piston are substituted for the rotating move-
ment appliances described in that Specification.
And having thus described and ascertained the nature of this my Invention I
declaro that I claim,-
Firstly. An apparatus for cutting or undercutting coal or other minerals, con-
sisting mainly of a carriage on which is mounted a lever fitted with pick or tool
having a percussive action and capable of being moved in an arc, the carriage being
moved forward as required, all substantially as set forth.
Secondly. The construction of coal-cutting machine as described with reference
to the accompanying Drawings, and especially the construction of the lever B, and

page_text: the mode in which the "percussive engine" is constructed, fixed, and adjusted on
the lever.
In witness whereof, I, the said Johan Richard Schram, have hereunto set my
hand and seal, this Twenty-first day of March, in the year of our Lord One
thousand eight hundred and seventy-nine.
JOHAN RICHARD SCHRAM. (L.S.)