Improvements in Flexible Pipe Couplings for Railway Brakes and other Purposes.
Year: 1887

page_text: COMPLETE SPECIFICATION.
Improvements in Flexible Pipe Couplings for Railway Brakes and
other Purposes.
I, MATHURIN DÉSIRÉ LEGAT of 42 Rue de Chalon Paris France, Engineer, do
hereby declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:-
My Invention relates to improvements in flexible pipe couplings, and particularly
to those employed in connection with atmospheric railway brakes. Experience has
shewn that pipe couplings of india rubber whatever may be their form or composition
and however carefully they may be made are very liable to burst and cause the
unexpected stoppage of trains and thus imperil the safe working of the railway and
as these failures are inherent to the nature of the caoutchouc itself, my invention is
designed to remedy these objections by providing a flexible pipe coupling in which
the use of india-rubber is entirely avoided.
The preferred arrangement is that which I have represented in figure 1 of the
accompanying drawings, consisting of a tube made entirely of metal, drawn copper
for example, which is crimped or corrugated circularly, as shewn on a larger scale in
figure 2; or spirally, as in figure 3, the corrugations or spirals being made sufficiently
deep and close together; or the bellows-like tubes may be made of flat or dished
annular, discs united together by lap joint soldering, or in other suitable manner, as
shewn in figures 4 and 5. The tubing may also be made partly rigid and partly
flexible and with or without joints, as shewn in figures 6, 7, and 8. The flexible
portions may either be formed in the manner above described or be made of tubing of
round, flat, or other form, in cross section, bent or wound upon itself, or in the form
of spirals as in Figure 9, or in any other form affording the maximum degree of
flexibility. The joints A may either be simple or universal, and may either be
cylindrical, conical, or spherical with their axes parallel, at right angles, or oblique to
one another.
The telescopic forin of coupling may also be employed in order to bring the tubes
to the desired length and inclination, according to the requirements of the coupling to
be made.

page_text: -
The flexible corrugated portions of the pipe coupling in certain cases and for
certain purposes, may be made partially or entirely of other materials than metal
provided the material be sufficiently flexible and resisting, for instance, of guttapercha,
celluloid, leather, waterproofed fabrics, &c., and they may be strengthened externally
preferably by being wound with a spiral wire coil see figure 10 whereby the desired
strength and flexibility are ensured."
The union joints B of the flexible pipe couplings with the main pipe and the
joints C which unite the flexible pipe couplings themselves, are represented in section
in Figures 11 and 12, but the invention is not limited to these particular forms of
union joints.
The joint B Figure 11 is of special form and consists of a male or spigot end D
and a female or socket end E connected by a nut F, a perfectly tight joint being made
by means of a packing inserted between the shoulders on the parts D and E. The
nut F is held tight so that leakage at the joint is impossible notwithstanding vibration
and shocks, by a spring G fixed preferably to the socket end E, either at M or N, its
free end engaging in notches in the circumference or end of the nut F.
The union joint C Figure 12 differs from that above described inasmuch as it is
designed to be rapidly and efficiently coupled and uncoupled by hand. To this end
the screwthreaded parts of the joint are mutilated so that the two male and female
screws may be slid longitudinally the one into the other and caused to engage by a
partial turn, a packed or stuffing box joint being made between the portions H and I
of the coupling by an annular rib on the former entering a corresponding groove
containing the packing in the latter. The nut Jis locked by a spring K fixed
preferably in the grooved flange I of the part I, the end of this spring engaging
with notches made in the end of the nut J so as to prevent the latter from becoming
slackened by vibration.
When the corrugated portions of the flexible pipe couplings are made of thin
metal, it may be necessary, in order to prevent excessive elongation and consequently
any deformation or fatigue of the metal under an excessive internal pressure, to limit
the stretch of the corrugated or bellows like portions by means of internal stays, as
shown in Figures 13 and 14.
The flexible joint represented in Figure 13 consists of the corrugated or bellows-
like thin metal portion N suitably united to the screw socket pieces which are each
provided with a central eye P to receive the tie rod or stay Q. This central rod is
formed preferably of two screwthreaded stems each having a spherical head received
in a corresponding seat in the eye P, the two screwthreaded stems being connected by
means of a coupling socket R. This form of stay may be replaced by a rigid or
jointed connection in one or more pieces, but in any case provided with universal or
ball and socket joints at the ends so as to permit of the free flexure of the coupling in
all directions.
To the screw sockets O are connected the screwthreaded ends of straight or elbowed
rigid pipes, the whole forming a flexible coupling of the desired length and form
adapted to all the requirements of the service. By means of the arrangement above
described, the maximum degree of flexibility of the bellows like or plaited portion of
the tube is obtained and cannot be exceeded when the two parts of the coupling are
bent at such an angle that the corrugations or plaits are in close contact with each
other at the one side, and distended at the other, within the limits prescribed by the
central tie rod Q.
If it is desired to limit the degree of flexure otherwise than by the contact of the
corrugations with each other, the arrangement shown in Figure 14 may be adopted,
in which the sockets O are provided with cups enclosing and protecting the corrugated
or bollows-like part of the joint, the edges of these cups meeting and limiting the
degree of flexure of the joint. The same effect may be obtained by means of internal
abutments formed by a prolongation of the central tie rod, or by means of external
abutments or other means acting either in compression or tension of limiting the
flexibility of the joint.
In certain cases a sufficient degree of flexure can be obtained by means of concentric

page_text: tubes suitably corrugated and united, as shewn in figure 15, without the use of a
central tie rod or abutments whether internal or external for limiting the elongation
of the tubes.
In applying these flexible pipe couplings to the Westinghouse brake gear and in
other similar cases, they are preferably constructed of metal on account of its
strength and durability and the arrangement about to be described possesses the
requisite flexibility.
Figures 16 to 20 illustrate the preferred arrangement of flexible pipe coupling for
a Westinghouse brake entirely composed of rigid members E B, D, FG, HK, in
any suitable number, form or dimensions, connected by spherical joints formed by
male and female parts fitting the one in the other and pivoted together as shewn in
figure 18, so as to allow of the necessary angular movements. These spherical joints
are very strong and allow of the pipes being moved as required, the end joint being
in particular free to turn in any direction. For this purpose, the female spherical
part B which is attached to the end of the fixed pipe on the vehicle is pivoted on a
vertical axis by gudgeons and sockets M N to an encircling ring A, as shewn in
elevation in figure 16 and separately in plan in figure 17. This ring is itself similarly
pivoted on a horizontal axis upon the spherical male part of the coupling so as to
enable the latter to readily adapt itself to all lateral and vertical movements of the
vehicles. In case it is desired that the coupling box L attached to the end member H, K
of the pipe coupling, should also be capable of turning, the arrangement represented
in figure 20 may be employed. The joint employed in connection therewith is
preferably of the kind hereinbefore described. These hollow spherically jointed
casings enclose and protect a metallic flexible bellows like chamber by which the
members of the pipe coupling are in communication with each other and to which
they are connected, as shewn in section in figure 16, either by means of a binding
screw or otherwise, the internal pressure being often sufficient to ensure perfectly
tight joints which are preferably packed with india rubber or other elastic packing
with which may be combined a spring j, as shewn in figure 21, to ensure a tight joint,
whatever the direction of the pressure. In this case, the stuffing box K receives the
inner tube e attached to the coupling box L and formed with a collar with a
packing on each side compressed between a screw gland or nut and the coiled
spring. This mode of connection permits of rotary motion and maintains a perfectly
tight joint. The spherical casing joints have flanges by which the relative angular
motions of the members of the coupling are limited in order to avoid unduly straining
the corrugated or bellows-like chambers uniting the pipes. As the internal pressure
and all other strains necessarily take effect upon the steel pivots and sockets, the
flexible or bellows chambers will be effectually protected from shocks and undue
strain. The bellows-like chambers may also be protected from dust and the weather
by an enveloping jacket of some impervious fabric or material secured at the ends
by metallic rings or otherwise whether in turn enclosed in spherical joints or casings
as above described or whether the pipe sections be connected by jointed ears.
The above arrangements which are of a nature to ensure the efficient working of
the pipe couplings may, however be modified to suit each particular application. It
will be seen that the coupling pipe may be made entirely of metal, including the
flexible corrugated or bellows-like chamber connecting together the rigid members of
determinate form, in such manner as to ensure in all cases, the necessary mobility or
flexibility.
Having now particularly described and ascertained the nature of the said invention
and in what manner the same is to be performed, I declare that what I claim is ;-
1st. A pipe coupling for atmospheric or vacuum railway brakes, composed entirely
of metal and rendered flexible either throughout or for a portion only of its length
by means of circumferentially corrugated or bellows like chambers made of thin
metal connecting the lengths of rigid tube, as hereinbefore described and illustrated
in the drawings.
2nd. A metallic pipe coupling flexible in all directions, constructed of rigid tubes CG

page_text: jointed together by hollow spherical joints forming casings to enclose and protect
flexible corrugated metallic connecting chambers M, substantially as shewn and
described for the purpose specified.
3rd. In a flexible metallic pipe coupling formed of rigid tubes jointed together by
spherical or other joints enclosing flexible metallic connecting chambers as described,
the method of pivoting the two parts of the joints either by means of a pair of
pivots D or by means of a ring A, provided with pivots C2 C3 at right angles to the
first two, the one pair forming the pivotal axis for the male part and the other pair for
the female part of the joint as described, for the purpose specified.
4th. In the metallic pipe coupling for compressed air or vacuum brakes formed of
rigid tubes connected by flexible metallic chambers as described, the employment of
a stuffing box K in which the tubular part of the coupling box L rotates freely and
containing a packing composed of one or more rings eg compressed between a
spring and gland has described for the purpose specified.
D
30 2
1
1000