AN IMPROVED TENSION DEVICE FOR ROLLER BLIND CORDS
Year: 1876

page_text: LETTERS PATENT to George Andrews, of Ashford, in the County of Kent,
for the Invention of "AN IMPROVED TENSION DEVICE FOR ROLLER BLIND
CORDS."
Sealed the 1st September 1876, and dated the 31st May 1876
PROVISIONAL SPECIFICATION left by the said George Andrews at the Office
of the Commissioners of Patents on the 31st May 1876.
GEORGE ANDREWS, of Ashford, in the County of Kent.
DEVICE FOR ROLLER BLIND CORDS."
"AN IMPROVED TENSION
My Invention relates to an improved device for keeping the cords of roller blinds
in tension in order to hold the blind in any position in which it may be placed.
The advantage of my Invention over the ordinary rack is that by its spring
nction allowance is made for the stretching or shrinkage of the blind cord by
variations of temperature, a uniform tension being at all times maintained on the
cord, which is neither too tight nor too loose, as is generally the case when the
common rack is used.
Another advantage is that the blind can be more readily drawn down, as by
compressing the spring the cord is slackened and the blind will run down by its
own gravity.
The improved device of this Invention consists of a spring rod sliding tele-
scopically in a suitable case from the lower end of which it projects, said rod
terininating at the lower end in a ball or other shaped knob or head with a rounded
groove across its under side for the blind cord to run in.
The spring rod is reduced at one part which is made square and slides through
a square guide in the case to keep it in one position. This part carries the spiral
which is also contained in the case and presses the rod and knob downward.
Instead of a fixed knob the cord may pass round a pulley running loose on a pin.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said George Andrews in the Great Seal Patent Office on the 29th November
1870.
GEORGE ANDREWS, of Ashford, in the County of Kent. "AN IMPROVED TENSION
DEVICE FOR ROLLER BLIND CORDS."
My Invention relates to a spring tension device for the cords of roller blinds.
The advantage of a spring tension device over the ordinary rack is that by its
clastic action it compensates for the stretching or shrinking of the blind cord by
[Price 4d.]

page_text: variations of temperature, a uniform tension being at all times maintained on the
cord, which is neither too tight nor too loose, as is generally the case when the
common rack is used.
Another advantage is that the blind can be let down more readily, as by com-
pressing the spring the cord is immediately slackened and the blind will run down
by its own gravity.
The improved device of my Invention consists of a spring stom fitted to slide
telescopically in a case and terminating at its lower projecting end in a knob or
head with a rounded groove across its under side for the blind cord to run in. The
stem is prevented from turning by a guide, and carries a spiral spring which
presses the knob downwards. A pulley may be substituted for a fixed knob for the
cord to run on.
Figure 1 is a front elevation, and Figure 2 a vertical section of one arrangement
of the tension device, which consists of a tube or case A, preferably of cylindrical
form, and provided with projecting ears B by which it is screwed in position to
the window frame; D is a ball or other shaped knob on the lower end of a plunger E
fitted to slide in the lower end of case A from which it partly projects, as shown.
This knob D is provided with a rounded groove F at the under side for the blind
cord G to run in. The plunger E is on a stem H of smaller size to make room for
a spiral spring I, the stem H passing through a corresponding hole in the end A¹
of the case A, and being made of square or such other form in cross section as to
prevent the knob D turning round in the case and so keep the groove F always
in one direction. The stem H is secured by a pin, collar, or other means at the
upper end, which is enclosed by a tubular cap K fixed on the case A., after the
stem H is secured, this cap being of sufficient size and height to allow the stem H
with its collar or pin to slide freely up and down. The spring I is compressed
between the end A' of the case and the plunger E upon which it bears, thus
causing the knob D to maintain an elastic pressure on the cord G and keep it
always in tension.
Figure 3 represents a front elevation and Figure 4 a vertical section of the
tension device provided with a grooved pulley L for the cord to run in instead of
the knob D, the pulley being mounted on a pin in a fork M attached to the stem H
and plunger E. In this arrangement the stein E consists of a half round rod bent
double, as shown, with its ends secured in a tube E forming the plunger, and the
fork M attached as shown. The cap K fits in the open upper end of the case A
and is secured by a cross pin N which passing through the opening left for the
purpose between the two parts of the doubled stem serves also to prevent the stem
turning round.
b
Having described the nature of the said Invention, and the manner of per-
forming the same, I declare that what I claim as the Invention to be protected
by the herein-before in part recited Letters Patent is, a spring tension device
constructed and operating substantially as shown and described for the purpose
specified.
In witness whereof, I, the said George Andrews, have hereunto set my hand
and seal, this 28th day of November, in the year of our Lord One thousand
eight hundred and seventy-six.
GEORGE ANDREWS. (L.S.)