IMPROVEMENTS IN APPARATUS FOR COMPRESSING AIR AND FOR WORKING PNEUMATIC RAILWAYS
Year: 1867

page_text: PROVISIONAL SECIFICATION left by Frederic Seiler at the Office of the
Commissioners of Patents, with his Petition, on the 23rd October
1867.
I, FREDERIC SEILER, of Berne, in the Republic of Switzerland, Gentleman,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
APPARATUS FOR COMPRESSING AIR AND FOR WORKING PNEUMATIC RAILWAYS," to be
as follows:-
This Invention relates, firstly, to certain hydro-pneumatic apparatus for
compressing and for exhausting air, and to parts connected therewith, and
their application for working pneumatic railways, for supplying air to blast
furnaces and other furnaces, and for other purposes.
The said hydro-pneumatic apparatus is an improvement upon certain single
acting hydro-pneumatic apparatus of my Invention, a modification of which
has been and is now employed in connection with the Mont Cenis railway
tunnel for supplying the compressed air for the rock boring machines and for
renewing the air in the tunnel.
This single-acting apparatus is constructed as follows:-An annular pit
is formed of masonry or of sheet iron, and filled with water. Into this pit an
inverted bell, cylinder, or air vessel of sheet iron, similar to a gas holder, is
made to dip. In the centre of the air vessel top is fixed a piston rod or
plunger which reaches downwards into a hydraulic cylinder placed in a.

page_text: chamber formed by the inner side or wall of the annular pit. The bottom of
the bydraulic cylinder is connected direct with the water-supply pipe. On
'the top of the air vessel is formed a tank which is weighted with water to the
extent corresponding to the desired air pressure. When water pressure is
-admitted under the piston of the bydraulic cylinder the air vessel is raised
'from its pit and fills with air admitted thro' a suitable suction valve; at
the end of the stroke the water supply to the hydraulic cylinder is stopped and
the escape opened, whereupon the weighted air vessel will gradually fall,
'thereby compressing the air contained in it and forcing it thro' a suitable
valve and pipes to the desired place. In order to keep up a uniformn supply
of compressed air two or more apparatus are employed acting alternately.
Now my present improved hydro-pneumatic apparatus is double-acting
compressing air and discharging compressed air both in the up stroke and
down stroke, resembling in its action the air cylinder and piston of an ordinary
blowing engine. The cylinder of this apparatus which I will call the air
'cylinder, is made of sheet iron and is similar to a gas holder. The lower end
of the air cylinder forms the outside of an annular pit, and the inner side of
this annular pit is formed by a second inverted cylinder of smaller diameter,
which forms at the same time the bottom of the air cylinder. The annular
pit is filled with water into which a third inverted cylinder or air vessel is
made to dip. This air vessel forms the piston of the air cylinder, and it is
provided with a piston rod secured to its top and passing downwards through
a stuffing box in the air cylinder bottom and thro' a second stuffing box
into a hydraulic cylinder placed in the centre of the chamber formed by the
interior of the air cylinder bottom. At the lower end of the said piston rod is
'fixed the hydraulic cylinder piston. The hydraulic cylinder is fitted with a
slide or other valve arrangement, by means of which the water is admitted
and again discharged at both ends of the cylinder alternately, in the same
manner as steam is in a steam cylinder. In the top and bottom of the air
cylinder suction and pressure valves are fitted, the latter leading by pipes to
an air accumulator: The air accumulator consists in an inverted cylinder or
vessel of sheet iron, again similar to a gas holder which stands in a pit filled
with water. On the top of the vessel a tank is formed for holding the water
by which the vessel is weighted to the desired air pressure. The compressed
air enters by a pipe passing thro' the bottom of the pit and reaching above
the water level, and a second pipe similarly placed conducts the compressed
air from the accumulator to its destination.
The principal object of my Invention is its application to the working of
pneumatic railway tunnels of steep gradients in mountainous districts.

page_text: Supposing by way of illustration that a tunnel of, say, 4,500 meters in length
and 5 meters in diameter, and of a gradient of one in ten, had to be worked,
the weight of the train being 200 tons, I propose to employ a hydro-pneu-
matic battery of three double-acting apparatus as above described, each of
10 meters in diameter, and leading to a joint air accumulator of 12 meters in
diameter, and weighted to give an air pressure of one-tenth of an atmosphere.
With a piston speed of 1 meter pr second the three apparatus will deliver
per second 212 cubic meters of air compressed to one-tenth of an atmosphere,
with which the train would be propelled upwards at a speed of about 9 meters
per second. The area of the air cylinder piston and the degree of compression
being given the sectional area of the hydraulic cylinder will depend upon the
head of water, but in most Alpine lines hitherto proposed and surveyed
more than abundant head & supply of water has been found for a working
pressure of some 40 atmospheres. The water supply pipe may lead direct to
the hydraulic cylinder, but I prefer to employ an intermediate accumulator.
I intend to employ air compressing apparatus similar to the above described,
but on a smaller scale, instead of blowing engines for blast and other furnaces,
smiths' fires, and other purposes where the amount of pressure required docs
not render the use of such apparatus impracticable.
My Invention relates, secondly, to an expanding piston and break waggon
for pneumatic tunnels. This waggon consists of two separate two-wheeled
trucks placed at a certain distance from each other, and connected by means of
a strong shaft, the two ends of which are secured to two pedestals, one of
which is carried by each truck. The axis of this shaft is in a line or nearly
so with the axis of the tunnel. Upon this shaft and between the two trucks
are placed two or more plate iron discs of a diameter about one to three
feet less than the diameter of the tunnel. Around the outsides the discs are
provided with an annular lining of wood projecting some distance beyond the
iron. To these linings is secured between each pair of discs by belts of
leather or other material, or by iron knee joints, an annular tube of stout
prepared india-rubber, which keeps the discs apart from each other, the
several discs with india-rubber tubes together having the appearance of large
cylindrical bellows. The several discs are further connected by sheets or
hose of canvas, or canvas combined with other material, reaching from disc to
disc, and covering loosely so as to "bag" the india-rubber tubes. This
sheeting or hose is furnished with long fibre similar to the fibre used for
street-cleaning machines and brooms, each sheet connecting two discs forming
as it were a flexible brush, the extremity of the fibre or brush slightly
touching when the india-rubber tubes are in their normal state the sides of

page_text: the tunnel and acting as packing to the piston waggon. If it is desired to
bring a larger surface of the brush in contact with the sides of the tunnel the
several discs are drawn or pressed together by screws connected with each
other through gearing. The india-rubber tubes are by this means compressed
in one direction, but at the same time made to expand outwards, thereby
forcing the brush against the sides of the tunnel. The friction caused by
the brush surfaces against the sides of the tunnel can through this expanding
piston be regulated at will, and may be increased so as to act as a break of
sufficient power to arrest the progress of the train at any moment.