IMPROVEMENTS IN APPARATUS FOR OPERATING SIGNALS USED ON RAILWAYS
Year: 1879

page_text: LETTERS PATENT to Henry Johnson, of Eccles, in the County of Lancaster,
Engineer, for the Invention of "IMPROVEMENTS IN APPARATUS FOR OPERATING
SIGNALS USED ON RAILWAYS.”
Sealed the 25th June 1880, and dated the 27th December 1879.
PROVISIONAL SPECIFICATION left by the said Henry Johnson at the Office
of the Commissioners of Patents on the 27th December 1879.
HENRY JOHNSON, of Eccles, in the County of Lancaster, Engineer. IMPROVE-
MENTS IN APPARATUS FOR OPERATING SIGNALS USED ON RAILWAYS."
"
•
My Invention relates to that part of signalling apparatus which connects the
actuating lever to the arm or other such part of the signal, and consists in a method
of compensating for alterations (due to temperature) in the length of the con-
necting wire chain or other such apparatus. For this purpose I introduce within
the length of wire or chain a reservoir of fluid provided with a cylinder and piston,
which fluid on its expansion or contraction, according to atmospheric changes,
regulates the tension of the said wire or chain.
In carrying out my Invention I connect one end of the interposing wire or chain
to the aforesaid piston, and the other to the reservoir or cylinder. As therefore
the wire or chain expands or contracts and the liquid in the reservoir follows the
same law the piston will be forced or drawn in one direction or the other, thereby
effecting the required compensation.
The capacity of the reservoir is regulated according to the wire or chain in use,
and according to other conditions.
The apparatus above described I propose to mount upon wheels, so that the
whole may be moved bodily for the purposes of signalling, and to place it at an
angle to compensate for the friction of the wire or chain.
As an alternative of using a fluid in the aforesaid reservoir I attach to the
apparatus a bar or compound bars of metal, which, by expansion and contraction,
act in a similar manner to that above described.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Henry Johnson in the Great Seal Patent Office on the 26th June
1880.
HENRY JOHNSON, of Eccles, in the County of Lancaster, Engineer. “IMPROVE-
MENTS IN APPARATUS FOR OPERATING SIGNALS USED ON RAILWAYS."
My Invention relates, firstly, to that part of signalling apparatus which connects
the actuating lever to the arm or other such part of the signal, and consists in a
method of compensating for alterations due to temperature in the length of the
connecting wire, rod, chain, or other such apparatus. Figs. 1, 2, 3, of the accom-
panying Drawings illustrate one method of carrying my Invention into effect.
Fig 1 is a plan, Fig. 2 is a side elevation, and Fig. 3 an elevation in section, the
same letters of reference referring to the same parts in each Figure. At 1 is a
cylinder closed at one end by a cap 2, and at its other end is a cup-leather 3 held
in its place by a screwed gland 4. Passing through the cup-leather 3 and into the
interior of the cylinder 1 is a piston or ram 5, provided at its outer end with a
cross-head 6, to which are connected side rods 7, 7*, joined together and forming a
loop at 8. These side rods are supported at 9 by passing through lugs formed on
a guide 10 sliding loosely upon the outside of the cylinder 1, and fastened thereto by
set screws 11, 11*. At one side of the cylinder 1 there is a projecting part 12, into
which is screwed a pipe 13, the interior of which communicates with the cylinder by
the opening 14; this pipe 13 is closed at the end opposite to that screwed into the
cylinder 1. At 15, 15*, are rollers for supporting the cylinder 1 and pipe 13, and
upon which they are free to traverse. The pipe 13 and cylinder 1 contain a fluid,
and when such fluid expands by an increase of temperature the piston or ram will
be forced outward in direction of the arrow, but on again contracting by cooling
the piston or ram will be forced inward, as I shall hereafter explain. At 17, Fig. 4,
is the hand lever, as ordinarily used for actuating semaphore signals; at 18 is an
ordinary semaphore signal post, the arm of which is pulled to danger by means of
the usual weight 19; at 20 is the wire or chain, which is used to connect the hand
lever 17 and semaphore 18, but broken off for convenience of illustration. This
wire is subject to variations of length caused by variations of atmospheric tempe-
rature, such variations of length causing the semaphore arm to be raised higher or
lower as the said wire contracts or expands. To compensate for such contractions
or expansions I insert the apparatus, as shewn in Figs. 1, 2, 3, between the hand
lever 17 and signal 18 in the following manner, the same letters of reference being
used as in Figs. 1, 2, 3, when referring to similar parts:-The pipe 13 is jointed to
the hand lever 17, and the piston or ram is connected through the cross-head 5 and
side rods 7 to the wire 20 connected to the lever 21 of the ordinary semaphore
signal arrangement. When the band lever is pulled over to work the signal such
movement tends to force the ram or piston within the cylinder, but the fluid con-
tained in the cylinder preventing the movement if the ram the ram and cylinder are
drawn bodily forward, which, by means cross head, side rods, wire, or chain, actuates
the signal in the usual manner. Upon an increase of atmospheric temperature
taking place the wire or chain 20 becomes expanded, but such increase of tempe-
rature expanding the fluid contained within the pipe 13 and cylinder 1 the ram 5
is forced outward in the direction of the arrow, thereby taking up the slack wire or
chain which would otherwise have existed. If, on the contrary, the atmospheric
temperature decreases and the wire 20 contracts, the fluid also contracting allows
the piston or ram to be moved in an opposite direction by the weight 19, and
thereby keeping the wire or chain 20 at an uniform tension.
Fig. 5 illustrates an arrangement whereby I make the pipe containing the fluid
a continuation of the piston or ram.
At 22 is a cylinder provided with a cup leather packing at each end 23, 23*.
Passing through this cylinder and projecting at each end is a piston or ram 24, one

page_text: half of which I make of a larger diameter than the other. At 25 is the pipe, as at
13, in Figs. 1, 2, 3, and 4, screwed to the smaller end of piston 24. This piston
has an opening up its centre communicating with the interior of the cylinder 22 by
means of the aperture 28. The opening up the centre of the piston 24 is a con-
tinuation of the pipe 25, and as the fluid contained therein expands and presses
against the larger end of the ram the said ram or piston will be moved in the
direction of the arrow. When the said fluid contracts the larger end of the ram
can then be forced further into the cylinder 22. It will be seen that this arrange-
ment of piston and cylinder may take the place of that described in reference to
Figs. 1, 2, 3, and 4, if desired. The pipe 13 containing the fluid will vary in length
or internal capacity in proportion to the length of wire used in actuating the
signal. The cylinder and piston or ram must be so proportioned that the fluid
expansion shall give a movement to the ram equal to the amount of expansion of
the wire due to the same increase of temperature.
Having thus described and ascertained the nature of my said Invention, and the
manner in which the same is to be performed, I desire it to be understood that I
claim as secured to me under the above in part recited Letters Patent, the use of a
fluid, the expansion and contraction of which acting through the medium of a
piston and cylinder compensates for variations in the length of signal connecting
wires, rods, or chains arising from varying atmospheric temperature.
In witness whereof, I, the said Henry Johnson, have hereunto set my hand
and seal, the Twenty fifth day of June, in the year of our Lord One thousand
eight hundred and eighty.
HENRY JOHNSON. (L.S.)