Improvements in Air Signalling Mechanism for Railway Trains
Year: 1895

page_text: Date of Application, 30'n Apr, 1895-Accepted, 15th June, 1895
COMPLETE SPECIFICATION
Improvements in Air Signalling Mechanism for Railway Trains
I, CHARLES GOODWIN EUFRY, of No West 72nd Street, in the City, County
and State of New York, United States of America, Manufacturer, do hereby
declare the nature of this invention and in what manner the same is
performed, to be particularly described and ascertained in and by the following
statement
-
to be
The present invention relates to fluid signal mechanism, especially adapted to be
operated for the purpo e of signalling from any one car of a railway tram to the
locomotive
It is common to employ a signal train-pipe connected to a main or supply
reservoir by a valve mechanism adapted to maintain in the pipe an artificial or
greater than atmospheric pressure, anl to effect signals by suddenly reducing the
signal pipe pressure, as at one of the cars, thereby operating valve to let signal
pipe air escipe and sound a signal whistle or otherwise actuate a signal mechanism
at the locomotive
Such a signal system is limited in practical use to passenger trains, and this
limitation is essentially because of the time that must elapse between successive
Signals After a reduction of pies ure in the signal pipe, the tendency is for the
pipe to be recharged from the main reservoir, and hence the time consumed between
two signals is that of the forward travel of the reduction wave together with that
of the backward travel of the recharging wave, that is, in practice this is true, the
common rule being, even in the case of short trains, to slowly count four between
successive signal reductions Expertence shows that such an air signal system
cannot be successfully employed for trains of greater length than from 10 to
whereas it is highly desirable to have an efficient air signal mechanism
adapted to operate practically on trains of any length, as well as to operate more
certainly and rapidly than do the common signal mechanisms
15 cars,
Another cause of the uncertainty of the desired actin in common systems is that
a diaphi igm whistle valve is usually employed, which if not forcibly actuated is
likely to respond to the reservoir or to iccurient wave impulses and effect a
plun ih
of whistle signals for one train pipe reduction, especially if such reduction
is quickly and sharply made
It will be readily understood that if the signal column of air be of relative high
pressure, fluctuations thereof will be transmitted along the column at a greater
speed than would be the case with a column of lower pressure, and that a pressure
impulse will be transmitted more rapidly than a reduction impulse as also, that,
if the pressure impulse or added an be allowed to escape from the column, as for
sounding a whistle and restoring the column to standard pre sure, recurrent of
reservou-supply wave action will be avoided, the time of re toring column pressure,
as commonly, will be eliminated, and properly timed successive signal pressure
impulses can be added to the column without waiting for the first impulse to be
vented between successive signal impul cs
It is the object of my invention to avail of these principles and my invention
con 1 ts, generally, of an air signil train pipe, means for adding to or incre ising
the pre sure therein, and signal devices idapted to be operated by such incrcase
pres ure to exhaust the same from the train pipe
In the drawings,
igue 1 is a diagrammatic view of a mechanism embodying my invention

page_text: igure 3 is a like section with the valve open
Figure 4 is a like section of the valve casing or shell, the valve being removed
Referring to these views in detail, 1 represents the train pipe of an automatic
5, the air
This
biake system 2, the main reservoir thereof, 3 and 4, one of the auxiliary
reservoirs and one of the brake cylinders of an equilibrio construction
signal train pipe 7, a reducing valve connecting the signal pipe to the main
reservoir 2, 8, a branch from the signal pipe to the auxiliary reservoir 3, and 9, a
conductor's valve and operating handle whereby the branch signal pipe can be
opened or closed to effect or cut off flow of ur from the said reservoit to the signal
pipe 10 is the whistle, which is in open communication, above the reacting
piston 11, with the interior of casing 12 of the whistle valve mechanism
mechanism consists of the dnect acting valve 13 normally closing the train pipe
passage 14, and of said piston 11 attached to the valve 15 being elongated ports
the innui face of the ca ing, which normally are clo ed by said piston as to
communication between the casing spaces above and below the piston The
valve 13 is held closed under the tension of spring 16, bearing on the piston and
resting in the screw nut 17, which is threaded in the casing, opens to the whistle,
and is adjustable to govern the opening of the valve at various train pipe pressures
Exhaust ports 18 are also provided, which open the chamber 19 below the piston
to the atmosphere, and which are normally closed by the piston
This combination of a valve with a piston of greater diameter produces in effect
a differential or reactionary valve mechanism, or one that is acted on to open at
certain pressure, is again acted on more powerfully to hold open on to open more
widely until it has exhausted to below that pressure before closing The
chamber 19 is essential to the use of this valve for exhausting air from a signal
pipe in that it forms a space in which the escaping air can collect and form a
cushion to steady and maintain the valve in open position aud prevent its vibratory,
or rapid opening and closing, movement under slight variations of exhaust
pressme
In the running condition of the air brake and signal mechanisms, the main and
auxiliary reservoirs are to be charged at a considerably higher pressure than the
signil pipe say at seventy and thirty pounds 1 espectively, the latter pressure being
maintained by the reducing valve between the signal pipe and the main reservoir
of the brake system, and the whistle valve is to be set to move from its seat at a
pressure slightly above that of the signal pipe
When it is desired to signal the engineer, the conductors signal valve will be
turned for a moment to open the pipe connecting between the auxiliary reservoir
and the signal pipe, and immediately closed, which will result in sending a pressure
impulse or wave along the signal pipe When this added pressure on pres ure
impulse wave aves at the whistle valve the latter is raised and admits signal
pipe pressure to under the piston attached thereto which piston being of greater
are is yet more strongly acted upon and is raised to position shown in Iigure 3,
at which position of the parts the signal pipe an escapes to the whistle and also to
the atmosphere, depending upon the amount of pressure added in the sign il pipe
The whistle valve is to be set so that it will exhaust signal pipe air until the
pressure of the same is slightly below that at which the valve will open the normal
oi standard pressure carried in the signal pipe
It is to be noted that the excess pressure or signal valve escapes at the whistle
valve leading the retained signal pipe air at noimal pressure, and hence there is
practically no recurrent or backward wave Al o, the signal pipe supply 1- not
drawn upon (rather, it is cut off) by the action of the pressure impulse, and hence
the time between successive signals need be that only of the exhaust of a pies ure
impul e from the pie, and a scries of successive impul es can be sent along the
pipe by the conductor without regard to their reception at the locomotive and with
the certainty that they will effect a corresponding number of separate signals
A large number of practical tests of this signal mechani m on a stan laid train-
pipe line of fifty cars in length, has proved th it successive signals can be sent from

page_text: one end to the other of such a line with a pause between siguals not greater than
is now required in common systems when used on short trains, also, that one or
more impulses can be travelling the line while, for example, an impulse is being
sent in and one taken off the line
sure
When it is deemed necessary, as for a long signal pipe the signal impulses may
be prolonged and thereby their peed and certainty of transmission mide more
I prefer to use such a signal system with an equilibrio brake system, since
the air drawn from an auxiliary resei voir in such a system cannot undesirably affect
the brakes, and the supply to the reservoir from the brake train pipe is as rapid as
ordinarily would be the exhaust therefrom for the purpose of signalling-the tiain
brake line acting as an extension of the main reservoir from which to draw the
signal impulses to be sent along the signal line, though it is obvious that, while a
convenience, the brake train pipe is not a necessary means for maintaining at a
car or cars the fluid pressure employed to effect the sign il pressure-impulse
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
--
1 In combination in a flud signal mechanism for railway trains, a signal train-
pipe and air pressure mechanism connected thereto and acting to maintain therein
an artificial standard air pressure, a signal mechanism connected to said pipe and
actuated by an increase to the pressure of the signal pipe above its normal pressure,
a chamber or reservoir normally containing air under pressure greater than that in
the signal pipe, and a valve mechanism connecting said chamber and signal pipe
and operable to increase the signal pipe pressure for the purpose of actuating said
Signal mechan sm, substantially as set forth
2 In combination in a fluid signal mechanism for railway trains, a signal pipe
air storage reservoir and an automatic valve acting to supply said pipe from said
reservoir and to maintain in the pipe a normal air pressure less than that normally
held in the reservoir, a signal mechanism connected to said pipe and actuated by
an increase of the signal pipe pressure above its normal pressure, a second train
pipe (or air-brake train pipe) connected to said reservoir and normally containing
an under pressure greater than that in the signal pipe, and mechanisin acting to
openly connect the two pipes whereby to increase the signal pipe pressure and
actuate said signal mechanism, substantially as set forth
3 In combination with the main reservoir, train-pipe and auxiliary resei vou of
an air-brake system, a signal pipe and valve mechani.m connecting the same to
said main reservoir and acting to maintain in the signal pipe a pressure less than
that in the main reservo, signal mechanism connected with the signal pipe and
operable upon and by an increase of signal pipe pressure above its normal pressure
and valve connections between the signal pipe and the auxiliary reservoir whereby
a can be drawn from the auxiliary reservou for the purpose of adding to the
signal pipe pressure and actuating suid signal mechanism, substantially as set
forth
4 In combination in a fluid signal mechanism for railway trains and with the
signal pipe thereof, mechanism for maintaining a certain stored or normal an
pressure therein, mechanism for increasing said air pressure, and a differential
signal valve controlling an exhaust passage from the signal pipe, whereby when
the normal pres ure in the signal pipe is increased said valve is operated to effect a
signal and reduce the signal pipe pressure to its standard or normal condition
Dated this 30th day of April 1895
HASELTINE, LAKE & Co,
45, Southampton Buildings, London, WC, Agents for the Applicant