IMPROVEMENTS IN ROCK BORING MACHINES
Year: 1876

page_text: LETTERS PATENT to Johann Richard Schram, of Norfolk Street, Strand, in the
County of Middlesex, for the Invention of "IMPROVEMENTS IN ROCK BORING
MACHINES"
Sealed the 17th March 1876, and dated the 11th January 1876.
PROVISIONAL SPECIFICATION left by the said Johann Richard Schram at
the Office of the Commissioners of Patents on the 11th January 1876.
sex.
JOHANN RICHARD SCHRAM, of Norfolk Street, Strand, in the County of Middle-
"IMPROVEMENTS IN ROCK BORING MACHINES."
Machines constructed according to this Invention have only four moving parts,
viz., the piston, the slide valve, the slide valve rod, and a cog for twisting the
piston and its drill or tool.
The piston has packing rings and bearing surface in two places, some distance
apart, the intervening portion being smaller in diameter; it is formed in one piece
or continuation with the ram, which passes out at the front or lower end, there
carrying the boring tool, and with the back part which is formed with helical
grooves and enclosed in a hollow head; the acting back area of the piston is
larger than the acting front area.
The slide valve is of ordinary construction, as regards the face or port part, but
is held between flanges of a double piston, each end of which is working in a cor-
responding cylindrical part of the slide jacket, its stroke being limited at each end
by the said flanges or conical faces on same coming in contact with one or other of
the edges of said cylindrical parts of the slide jacket. A cog on a small piston
works in a direction vertically to and into the helical grooves of the back part of
the piston or ram.
The construction will be best understood by describing the action of the
machine-Supposing the slide valve is in its extreme forward position, then steam
is admitted to the front of the main piston by a port. When the main piston has
gone back part of its stroke the steam is allowed to escape by a small extra port
to the back piston of the slide valve, the steam behind the other or front piston of
the slide valve at the same time being allowed to escape into the exhaust passage;
the back steam port will thus be opened and force the main piston forward,
iparting the necessary blow on the rock. This steam in the forward stroke is

page_text: similarly allowed to escape by an extra port or passage to the front piston of the
slide when the main piston has gone part of its travel, and the slide valve will
thereby be reversed as before; the steam on the back piston of the slide valve also
escaping into the exhaust as before.
As soon and as long as steam is working on the back part of the main piston,
the aforesaid piston with the cog on is lifted free of the grooved back part of the
main piston, which thus performs its forward stroke without turning and without
touching any other part, in consequence of which the blow is powerful; but in
the back stroke steam is by a small passage admitted above the cog piston and
forces the cog into one of the grooves, thereby giving the main piston and the
boring tool a twist in each back stroke.
Instead of this arrangement I sometimes fit or form the piston with ratchet
teeth, and make the cog piston press upon a pawl gearing into the ratchet teeth,
thus turning the piston.
The small steam passages are so drilled and arranged that they can be cleaned
by removing stop screws.
The feed is done by hand, as I have by experience found that automatic feed
is not suitable for general work owing to the variable nature of the work operated
upon.
The annum.
the Great Seal ratent Unce on the 11th
July 1876.
JOHANN RICHARD SCHRAM, of Norfolk Street, Strand, in the County of Mid-
dlesex. "IMPROVEMENTS IN ROCK BORING MACHINES."
Machines constructed according to this Invention have only four moving
parts, vizt.,
1. The piston, to which the drill or tool is fastened.
2. The slide valve.
3. The slide valve rod.
And 4. The cog for twisting the piston and its drill or tool.
All these parts are so constructed that they receive their motion from direct
contact with the steam, compressed air, or other impelling fluid, and so that they
are not exposed to the great wear and tear generally experienced in other rock
drills.
And in order that this my Invention may be fully and clearly understood, I
will now describe the same with reference to the accompanying Drawings, of
which,―
Figure 1 is a longitudinal section.
Figure 2, a plan of a machine constructed according to my Invention.
Figure 3 is a vertical cross section of a modified arrangement of the appliance
for giving the piston and tool the required twist.
Figure 4, shews the apparatus applied to vertical downward drilling.
And Figure 5 is a carriage or support for driving galleries and headings, the
stretcher screws A carrying the drills.
The rock drill here shown is proportioned for the use of steam.
The piston has packing springs d¹ and bearing surface in two places, some distance
apart, the intervening portion & being smaller in diameter, as shown. It is formed
in one piece or continuation with the ram d² which passes out at the front or lower
end, there carrying the boring tool, and with the back part m, o, which latter is
formed with helical grooves and inclosed in a hollow head c². The acting back area
of the piston at c², c², is larger than the acting front area at c.

page_text: The slide valve ƒ is of ordinary construction, as regards the face or port part, but
it is held between flanges f₁, f¹, of a double piston f, f³, each end 2 of which is
working in a corresponding cylindrical part k and g, respectively, of the slide
jacket, its stroke being limited at each end by the said flanges f¹, f¹, or conical
faces on same, as here shown, coming in contact with one or other of the edges of
said cylindrical parts k or g of the slide jacket. f³ is the part of the slide rod
which passes out through a stuffing box. By forming the slide rod with two valve
faces fi, f, it remains in position without recoil until the piston has made the
greater part of its stroke. is a small piston working in a direction vertically to
the back part o of the piston or ram, and formed with a cog which works into the
helical grooves formed in the said part o.
The action of the machine is as follows:-Supposing the slide valve is in its
extreme up position, as here shown, the stop-cock at a being open, then steam is
admitted by the port b in the cylinder e to the under part of the main piston d,
causing it to make a stroke upwards, but when the part d' has passed the small
extra port e the steam is allowed to escape thereby to the upper piston f2 in the
small slide valve cylinder g, the steam in the small cylinder behind the other.
piston of the slide valve at the same time being allowed to escape into the
exhaust passage 8 by the ports i and r. The steam thus let into g pushes the slide
valve rod and slide valve down, and opens the valve to the steam port h of the
main cylinder c; fresh steam from a then enters the part c¹ and c of the main
cylinder and forces it down, imparting the necessary blow on the rock. This steam
in the down stroke is similarly allowed to escape by the small extra port or
passage to the piston f' in the slide valve cylinder k when the main piston d has
gone part of its travel, and the slide valve will thereby be reversed as before, the
steam on the piston f2 in the slide valve cylinder g also escaping into the exhaust &
by the ports e, r; fresh steam then enters the main cylinder at c, acting on the
small piston surface, and the action is repeated as described.
As soon and as long as steam is working on the upper part d³, o, of the main
piston, the piston with cogs is lifted free of the grooved back part o of the
main piston, which thus performs its down or forward stroke without turning round
its axis and without touchiug or working any other part, in consequence of which,
the blow is powerful on the rock, the piston being perfectly free to receive and
give off all the power the steam can impart. But in the up or back stroke steam
is by a small passage m admitted to the space n above the cog piston 1 and forces
the cog into one of the grooves in o, thereby giving the main piston and the
boring tool or drill a twist in each up or back stroke.
Instead of the arrangement just described, I sometimes employ the arrrangement
shown at Figure 3. In this case the part o of the main piston is formed with
ratchet teeth also twisted lengthwise, as before described, and the cog piston is
made to press upon a pawl gearing into the ratchet teeth, thus turning the main
piston. The piston has a constant steam or air pressure on its upper face through
the passage m which communicates with the slide jacket. When steam is admitted
to the main cylinder at c¹, c², the pressure on both sides of the cog piston 7 is equal,
and as the main piston makes its down or forward stroke the pawl x slips easily
over the ratchet teeth in the part o of the main piston; but as soon as the space
at c¹, c, communicates with the exhaust, the pressure on the upper face of the cog
piston presses it against the pawla so that the latter engages with one of the
ratchet teeth in o, and when the main piston makes its up or back stroke it is
forced to make a slight turn.
l
The small steam passages are so drilled and arranged that they can be cleaned by
removing stop screws.
The feed is done by hand, as I have by experience found that automatic feed
is not suitable for general work owing to the variable nature of the work operated
upon.
The apparatus may also be worked by means of compressed air, or be adapted for
any other compressed fluid.

page_text: And having thus fully described the nature of this Invention, I would remark
that I am aware that E. S. Crease in the Specification of his Patent, dated 24th
October 1863, No. 2624, describes and claims the application of a piston slide valve
acted on directly by compressed fluid, and so that the said piston and the main
piston act as piston valves to one another, but what I claim is,
First. Forming or fitting the slide valve rod with two spindle valves and pistons,
and actuating the slide valve substantially as here set forth.
Second. Slide valve moving gear constructed as set forth operating in conjunction
with a main piston, substantially as set forth.
Third. Imparting rotary motion to the main piston and tool of a rock drill by
means of a piston in combination with cog or pawl appliance, and with a helically
grooved part of the main piston, substantially as set forth.
And, Fourth. The general arrangement of ports and passages for actuating main
piston, slide valve pistons, and cog piston, or pawl impelling piston, as here set
forth.
In witness whereof, I, the said Johann Richard Schram, have hereunto set my
hand and seal, this Sixth day of July, in the year of our Lord One thousand
eight hundred and seventy-six.
RICHARD SCHRAM. (L.S.)