IMPROVEMENTS IN PNEUMATIC RAILWAYS
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by Thomas Webster Rammell at the
Office of the Commissioners of Patents on the 29th June 1878.
THOMAS WEBSTER RAMMELL, of 5, Westminster Chambers, Westminster, in the
County of Middlesex, Civil Engineer. "IMPROVEMENTS IN PNEUMATIC RAILWAYS."
In the working of pneumatic railways it is desirable that the pneumatic pressure
should be brought to bear upon and be shut off from the train when within the
tubular way at the right moment by the opening and closing with precision of the
terminal doors and the valves provided for the purpose, and this will be better
effected by mechanical than by manual means.
In a former Patent I proposed to effect the opening of the terminal doors for the
delivery of the train by these means. I now cause the train to act automatically
in closing the terminal doors behind it on passing from the station into the tubular
way, and in afterwards opening and closing the valves by which the pneumatic
pressure is applied to and shut off from it. I effect these objects by transmitting,
according to the case, the action of the moving train to the spindles of the doors
and valves in question through the medium of hydraulic or pneumatic pressure and
the interposition of suitable tubes, pistons, bars, cranks, levers, and catches for the
purpose, being means the application of which is already well understood.
With pneumatic railways inconvenience is experienced from the present plan of
affixing the sail plate of the train to one of the ordinary carriages in use. The
springs of these carriages are necessarily made too easy to allow of an accurate
adjustment of the contour of the sail plate to that of the tubular way, and their
great width of body leaves an insufficiency of space at the sides for the proper play
of the wings of the sail plate.
I now place the sail plate upon a separate carriage constructed for the purpose, of
width suitable for the play of the wings, and sufficiently stiffened in the springs to
prevent unnecessary loss from windage. I make this carriage long enough to insure
the stability of the plate, and to afford room for the guard or driver's place as well,
and also for receiving the brake apparatus and the air vessels to be used for giving
motion to the train at stations in the manner to be described under the next head
of my Inventions.

page_text: With pneumatic railways the train when at a station is in a position in which
the pneumatic pressure ordinarily employed in the tubular way cannot be brought
to bear upon it. As the most convenient means of giving motion to the train when
so placed I now endow each train with a limited faculty for locomotive action after
the manner of a locomotive engine, and with similar appliances for the object.
The degree to which such faculty should be given will be an extremely limited
one, and I prefer to obtain the power for the purpose through the medium of com-
pressed air rather than by the use of steam. To this end I provide a small reservoir
for compressed air in the piston carriage, and this is either filled to the degree
required by proper pumps during the ordinary transit of the train through the
tubular ways, or is renewed from time to time from larger reservoirs provided at the
stations.
.
By these means motion may readily be communicated to the train at a station by
the act of the driver without extraneous assistance; at the same time to facilitate
the movement I prefer to lay the ways at stations with a slight inclination, say, of
1 in 100, downwards towards the section of tubular way to be entered in each case,
the fall thus given to the " up" and the "down" line at each station being
reversed.
With pneumatic railways it. is requisite that the pneumatic pressure should be
available at each station or at each alternate station, as the case may be, and the
transmission of the prepared current from a distance being impracticable it becomes
necessary that there should be the means of producing at the station itself the com-
pression or the rarefaction desired of the air to be employed.
To produce the compression or the rarefaction I make use of a centrifugal
inachine, by preference of that form which I call an ejector, but it is not necessary
that these machines should be driven directly by steam power produced on the
spot; they may be acted upon by steam at a high temperature by compressed air,
or by water under compression produced elsewhere, led through proper pipes to
each station where it is to be employed, and there received into suitable vessels for
its storage and application. Water, especially, may be thus raised and led without
much loss of power, and I consider this fluid compressed under a considerable head,
and made to act upon the turbine or other rotary machine by its ro-active force, as
the preferable means to be used, more particularly in the interior of a large city,
but reserve to myself the employment of other incans.
I prefer in the case named especially to make the ejectors and turbines compact
machines, occupying only so much space that the entire pneumatic apparatus for a
.station may be placed underground, whether at the side and on the same level as
the station itself or under and beneath it.