Improvements in Flexible Metallic Pipes for the Coupling of Conduits Used on. Railway Carriages and for other Purposes.
Year: 1888

page_text: Date of Application, 13th Aug., 1888
Specification Accepted, 14th Sept., 1888
Improvements in Flexible Metallic Pipes for the Coupling of
Conduits Used on. Railway Carriages and for other Purposes.
We, MATHURIN DÉSIRÉ LEGAT and LOUIS JOSEPH STANISLAS HERBET, Engineers,
both of 42 rue de Chalons, Paris (Republic of France), 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:-
Our invention relates to improvements in flexible metallic pipes more particularly
intended for coupling the compressed air or vacuum conduits employed on
railway carriages, but which may also be applied to all industrial purposes.
The flexible part of the pipe is made up of pieces of corrugated tube, such as
described in the specification of Patent No. 10321 granted to the above named
Mathurin Désiré Legat, and dated 23rd July 1887. The pipe is composed of a series
of these flexible parts connected together two by two, by rigid parts combined in such
a manner as to limit the degree of inflection, and to direct the inflections so that
they are caused to be produced round the centre of the form of such parts,
thereby preventing excessive strains, and also all cutting action on the juxtaposed
diaphragms or membranes of which such parts are composed, as well as on the parts
connecting same.
The result of this construction is to make each flexible part work regularly and in
the form that it ought to take under the combined action of the strains to which it is
subjected, so as to prevent any contortion being produced in the pipe, and to prevent
all abnormal strain.
Our invention also relates to improved arrangements applicable to the connecting
parts of the different lengths of pipe, when several are employed, in order to facilitate
the replacing of parts and repairs.
In the accompanying drawings Fig. 1 is a sectional elevation of a suitable form of
flexible pipe embodying our invention, and intended for use in connecting the conduits
itted to two railway carriages.
Figs. 2, 3 and 4, show different modes of connecting the flexible parts together.

page_text: Figs. 5 and 6 show different forms of joints to be used to connect two lengths
of pipe.
Fig. 7 shows a connecting ring of special form, which we prefer to employ.
As will be seen in Fig. 1, the flexible parts I are formed of thin plates which are
either (a) stamped out, butted against each other and soldered; (b) stamped out,
fitted over each other and soldered; (c) stamped out, screwed together and soldered;
or (d) (according to circumstances) they are made corrugated, either by
pressure on a mandril, or by pressure in a mould, (the compressed metal being
in a pasty condition if requisite), or by electro-deposition, or by any other suitable
means.
These parts which contain a variable number of plates, preferably a small number
(five for instance), are united two by two, by the connecting rings B arranged in such
a manner as to produce the effects above mentioned.
This connecting together of the flexible parts may be effected in various ways, for
instance by means of an external frame formed of ears, caps, etc., A, as shown in
Fig. 2. In this arrangement these frames are united to the connecting rings B, by
means of a half collar C which simply engages a groove formed in the outer
surface of each ring B, and they are connected together, one ring to another, either
directly by articulations, or by the intermediate rings D, to which they are articulated,
two by two (either by fixed or inserted pins E, or by any other suitable means), at
two points at right angles to each other, and passing through the centre of the form
of each flexible part, so as to form a very strong protecting frame capable of bending
in all directions.
The same result may be obtained by means of internal frames composed of articulated
rods, chains, caps, etc., F, connected to the connecting rings B, as shown for example
in Fig. 3. But in this case we preferably employ a flexible rod, such as a metallic.
cable (see Fig. 1) passing through guide sockets G formed in one with the rings
which connect the flexible parts I. The parts are arranged so that there is sufficient
space left between two adjacent sockets, at the middle of the flexible parts which they
also enter, to receive the articulation of the frame, rod, chain, cap, or equivalent part,
or to permit the part of the cable remaining free. or exposed, to hend in any
direction; these flexible or articulated frames at the same time that they form a
perfect universal joint, afford the requisite resistance and flexibility to the whole of
the pipe.
The rings B as indicated in Fig. 7, preferably have their boss cast with them,
and have a projecting flange B' on the rim, the diameter of which is a little greater
than that of the diaphragms or membranes of the flexible pipe; by these means
the latter are effectually protected against any blows the pipe may receive.
Like the other articulated frames, a separate cable may be employed for each
flexible part (see Figs. 2 and 3) or for each length of tube, and be fixed thereto at its
ends, either by forming a head X with a ring soldered to the flared out or enlarged
part of the cable; or by retaining the enlarged part of the cable between the end of
the central socket 6 of the piece Z, and a screw or head S secured by a screw cap T,
or by any other suitable means.
These frames (rods, ears, rings, chains, caps, or their equivalent) jointed either inside
or outside of the pipe, have also for object to offer an opposition to the action of the
internal pressure, by limiting the extension of the flexible parts, and consequently that
of the pipe, and also to hold the jointed parts together in an air-tight manner by the
automatic action of the pressure, which is effectually produced when this mode of
connection is employed for pipes to be used for the circulation of a fluid under pressure.
By these means instead of soldering the flexible parts to the connecting rings, as
indicated in Figs. 1, 2 and 3, we are enabled to automatically connect them in an
air-tight manner as shown in Fig. 4, and thus form flexible metallic pipes of any
length.
In order to facilitate the application of these pipes and permit of their general
employment, pipes of any length could, as above stated, be composed of lengths
containing a certain number of flexible parts united by one of the means above

page_text: described, and connected together by means of any suitable joint, for instance by
means of the enclosed joint constructed as shown in Fig. 1, and in which the packing V
of any suitable material is enclosed and compressed in a chamber made for this
purpose between the male part M and the female part K, the pressure between them
being exerted by means of a screwed nut L, which may be tightened up by hand.
In the enclosed connecting joint shown in Fig. 5, and which is of the same kind,
the nut has notches H, in one of which is inserted a screwed pin, carried by the
female part K, and which prevents the nut working loose. In order to turn the nut
the screw pin J has to be screwed right down into the tapped hole, which is made
deep enough to permit this.
This kind of enclosed joint is perfectly air-tight, and besides permits the jointed
parts themselves to turn, if requisite.
In the case where the pressure exerted within the pipe is sensibly less than the
external pressure, the excess of the latter over that of the internal pressure, would
suffice to compress the enclosed packing sufficiently to ensure an air-tight joint.
Thus, this joint has the same advantages as the preceding one. Instead of com-
pressing the enclosed packing between the male and female parts by tightening up
the nut L we may (as shown in Fig. 6) when the pressure inside the pipe is greater
than the external pressure, arrange the joint in the form of an inverted gland, so that
the packing may be confined between the male and female parts and the screw cap O,
working on the latter, and be there tightly compressed by the male part N, under
the automatic action of the effective pressure to which the pipe is subjected, and thus
secure an air-tight joint.
A spring P may be provided to aid the internal pressure, or to guard against any
deficiency which might occur of the latter, or even its complete failure; so as to
maintain the packing Q compressed, through the medium of ring R, in perfect
contact with the nut O.
In any case, this last arrangement of enclosed joint, has like those above described,
the advantage of being perfectly air-tight, and of permitting the jointed pieces to
turn on themselves in case of necessity.
As applied to conduits of compressed air or vacuum brakes, or all other connections
of conduits, the pipe constructed as above described, and by preference in two distinct
parts connected together, as shown in Figs. 1, 5 and 6, terminates at its upper end
in a socket Y provided with means for fixing it firmly to the neck of the main
conduit; its lower end terminating in a similar nut or socket Z, which can receive
the ordinary coupling joint in use, either directly, or by the intermediary of another
socket U fixed to the front of the coupling joint, or by means of one of the joints
shown in Figs. 5 and 6.
The pipe may if necessary be effectually protected against the introduction of
foreign matter between the flexible parts, or even against blows, by a flexible and
strong envelope or sheath of suitable material, fixed to the pipe by means of collars
or simple bindings.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is :-
1. A pipe made of a certain number of flexible parts I, such as described, such
parts being formed of a number of diaphragms or membranes, and being connected
together by rings, such as B, which increase the resistance and limit the amount of
flexibility, substantially as specified.
2. In a pipe, as described in the preceding claim, the employment for connecting
together the flexible parts I, of the connecting rings B having a rigid central boss or
socket traversed by the internal frame (flexible rod, jointed chain, cable, etc.,) in such
a manner that this frame can only bend at the part which is free between two
rigid bosses, that is to say towards the centre of the flexible part, substantially as and
for the purpose set forth.

page_text: 3. In a pipe such as described in claim 1, the employment of external frames, such
as ACE and A D E, articulated alternately first in one direction and then at right
angles thereto, so as to ensure flexibility in all directions, substantially as and for the
purpose set forth.
4. A. flexible pipe in two pieces, composed of the flexible parts I connected by the
connecting rings B (preferably such as shown in Fig. 7), the two pieces being
connected by a coupling, as herein described and shown in Fig. 1 of the drawings.
5. The special couplings, as herein described and shown in Figs. 1, 4, 5 and 6 of
the drawings, for connecting either two flexible parts (Fig. 4), or two lengths of
flexible pipe (Figs. 1, 5 and 6).