IMPROVE- MENTS IN COMPRESSING ENGINES, SUCH AS ARE USED FOR COMPRESSING AIR FOR WORKING COAL-CUTTING MACHINES, AND IN THE CUTTERS OF SUCH MACHINES
Year: 1875

page_text: LETTERS PATENT to John Alexander, of Gartsherrie Iron Works, in
the County of Lanark, North Britain, for the Invention of "IMPROVE-
MENTS IN COMPRESSING ENGINES, SUCH AS ARE USED FOR COMPRESSING AIR
FOR WORKING COAL-CUTTING MACHINES, AND IN THE CUTTERS OF SUCH
MACHINES."
Sealed the 4th May 1875, and dated the 24th February 1875.
PROVISIONAL SPECIFICATION left by the said John Alexander at the
Office of the Commissioners of Patents, with his Petition, on the
24th February 1875.
I, JOHN ALEXANDER, of Gartsherrie Iron Works, in the County of
Lanark, North Britain, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN COMPRESSING ENGINES, SUCH AS ARE USED FOR COMPRESSING
AIR FOR WORKING COAL-CUTTING MACHINES, AND IN THE CUTTERS OF SUCH
MACHINES," to be as follows, that is to say :-
This Invention has for its object the further improvement of apparatus
connected with coal-cutting machinery, and is intended to be carried out
along with the Inventions or improvements having a similar object, and

page_text: for which the present applicant has already obtained Letters Patent,
dated 19th December 1871 (No. 3438), and Letters Patent dated 3rd
September 1874 (No. 3009); but the present improvements or some of
them are also applicable to apparatus for compressing air for other
purposes, and to coal-cutting apparatus differing more or less from that
described in the Specifications of the earlier Patents referred to.
In compressing apparatus made with the present improvements there
is a main compressing cylinder having in it a piston made to reciprocate
by a steam engine or other prime mover. This cylinder is formed with
passages or ports at its ends opening directly into two small cylinders
formed upon or attached to the main cylinder, and having their inner
ends or those facing each other open.
The smaller cylinders are fitted with pistons, both of which are fixed
on one rod, and are made to reciprocate by an eccentric, crank, or cam
on a revolving shaft driven by the prime mover. The closed ends of the
small cylinders communicate through lift valves with branch pipes
leading to the main, by which the compressed air is led to the coal
cutting or other apparatus. These lift valves are guided on their upper
sides so as to reduce to a minimum the spaces between the cylinders and
their seats. Each valve is formed with a large central socket to work
on a fixed pin projecting down from the cover of the valve box, and
also with flanged feathers to work upon guide surfaces in the sides of
the valve box. The two pistons in the small cylinders act as a valve to
the large cylinder, the air entering by the open ends of the small
cylinders, and passing off in a compressed state through the valves in
connection with their closed ends.
The movement of the small pistons is by preference timed so thateach
just closes its port into the main cylinder as the main piston is arriving
at that end of its compressing stroke; and as the piston continues its
motion so as to uncover the ports towards its open end for the admission
of a fresh supply of air it forces the air in the closed end of the small
cylinder through the lift valve into the main. The small cylinders may
have their outer ends open instead of their inner ends, the lift valves
being of course always in communication with the closed ends.
In order to remove the heat rendered sensible by the compression of
the air, water is injected into the main cylinder in spray by means of two

page_text: single-acting pumps or one double-acting one, such pumps or pump
being worked synchronously with the main piston, and so as to deliver
the water into each end of the cylinder whilst the air is being
compressed.
The cutters for the coal-cutting machines, as made according to the
present Invention, consist of flat steel pieces with bevilled cutting edges
and with a slight convexity along the edges. Each cutter is held against,
a jaw formed on the link of the endless chain which carries the cutters
in machines of the kind referred to by a kind of claw bolt passing
through a hole in the cutter and a hole in the jaw, and retained by a
screw nut at the other end of the jaw, whilst a claw formed on the bolt
head fits in between the cheeks of the link, and thereby prevents the
cutter from canting.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Alexander in the Great Seal Patent Office on
the 23rd August 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
ALEXANDER, of Gartsherrie Iron Works, in the County of Lanark, North
Britain, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fourth day of February, 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 suc-..
cessors, give and grant unto me, the said John Alexander, Her special
licence that I, the said John Alexander, my executors, administrators,
and assigns, or such others as I, the said John Alexander, 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
COMPRESSING ENGINES, SUCH AS ARE USED FOR COMPRESSING AIR FOR WORKING
COAL-CUTTING MACHINES, AND IN THE CUTTERS OF SUCH MACHINES," upon the
condition (amongst others) that I, the said John Alexander, my executors

page_text: 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 calendar months next and immediately after the date
of the said Letters Patent.
NOW KNOW YE, that I, the said John Alexander, do hereby declare
the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement in writing, reference being had to the accompanying
Drawings, that is to say :-
My said Invention has for its object the further improvement of
apparatus connected with coal-cutting machinery, and is intended to be
carried out along with the inventions or improvements having a similar
object, and for which I obtained Letters Patent dated 19th December
1871 (No. 3438), and Letters Patent dated 3rd September 1874
(No. 3009), but my present improvements or some of them are also
applicable to apparatus for compressing air for other purposes, and to
coal-cutting apparatus differing more or less from that described in the
Specifications of the earlier Patents referred to.
My improvements in the air compressing apparatus relate to the
valves in connection with the air compressing cylinder, and consist in
an improved arrangement of piston valves combined with improved
check valves, the said piston valves expelling the compressed air from
the valve chambers, and the check valves preventing its return to those
chambers.
My improvements applicable to coal-cutting apparatus relate to the
cutters, and consist in making them of peculiarly shaped steel pieces,
and in fixing them to a kind of jaw formed on each link of the endless
cutter chain by a claw bolt passing through a hole in the cutter and a
hole in the jaw, and fixed by a screw nut.
And in order that my said Invention, and the manner of performing
the same may be properly understood, I hereunto append two Sheets of
explanatory Drawings to be herein-after referred to, and representing
my improvements. In these Drawings the same reference numerals are
used to mark the same or like parts wherever they are repeated.

page_text: Figure 1, on Sheet 1 of the Drawings, is a sectional side elevation, and
Figure 2 is a horizontal section of my improved air compressing apparatus,
which comprises the usual main compressing cylinder 1, having in it a
piston 2, made to reciprocate by a steam engine or other prime mover.
This cylinder is formed with passages or ports 3, 4, at its ends, opening
directly into two small cylinders 5, 6, formed upon or attached to the
main cylinder, and having their inner ends or those facing each other
open.
The small cylinders 5, 6, are fitted with pistons 7, 8, both of which
are fixed on one rod, and are made to reciprocate by an eccentric, crank,
or cam on a revolving shaft driven by the prime mover, but not shown
in the Drawing. The closed ends of the small cylinders 5, 6, commu-
nicate through lift or check valve ports 9, with branch pipes 10 leading
to the main 11, by which the compressed air is led to the coal cutting or
other apparatus. The lift or check valves 12 are each guided on their
upper sides so as to reduce to a minimum the spaces between the
cylinders 5, 6, and the valve seats or ports 9. Each valve 12 is formed
with a large central socket to work on a fixed pin 13 projecting down
from the cover 14 of the valve box, and also with flanged feathers 15 to
work upon guide surfaces in the sides of the valve box. The two
pistons 7, 8, in the small cylinders 5, 6, act like a common slide valve
relatively to the large cylinder 1, the air entering by the open ends of
the small cylinders 5, 6, and passing off in a compressed state through
the ports and valves 9, 12, in connection with their closed ends.
The movements of the small pistons 7, 8, is by preference timed so
that each just closes its port 3 or 4 into the main cylinder 1 as the main
piston 2 is arriving at that end of its compressing stroke, and as the
piston 7 or 8 continues its motion so as to uncover the ports 3 or 4
towards its open end for the admission of a fresh supply of air it forces
the air in the closed end of the small cylinder 5 or 6 through the port 9,
and past the lift valve 12 into the main 11. The small cylinders 5, 6,
may have their outer ends open instead of their inner ends, the lift
valves 12 being of course always in communication with the closed
ends.
In order to remove the heat rendered sensible by the compression of
the air water is injected into the main cylinder in spray by means of
two single-acting pumps or one double acting one, such pumps or pump

page_text: 3. The adapting and fixing of steel cutters to chain links in the
improved manner herein-before described with reference to Sheet 2 of
the accompanying Drawings.
In witness whereof, I, the said John Alexander, have hereunto set
my hand and seal, this Twenty-first day of August, in the year of
our Lord One thousand eight hundred and seventy-five.
the accompanying Drawings.
In witness whereof, I, the said John Alexander, have hereunto set
my hand and seal, this Twenty-first day of August, in the year of
our Lord One thousand eight hundred and seventy-five.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
JOHN ALEXANDER. (L.S.)