IMPROVEMENTS IN RACK PULLEYS FOR THE CORDS OF WINDOW AND OTHER BLINDS AND THE CORDS OF OTHER ARTICLES." PROVISIONAL SPECIFICATION
Year: 1880

page_text: LETTERS PATENT to Edwin Showell and Charles Showell, of the Firm of
Edwin Showell and Sons, of Birmingham, in the County of Warwick,
Brassfounders, and John Empson, of Birmingham aforesaid, Tool Maker, for
an Invention of "IMPROVEMENTS IN RACK PULLEYS FOR THE CORDS OF
WINDOW AND OTHER BLINDS AND THE CORDS OF OTHER ARTICLES."
PROVISIONAL SPECIFICATION left by the said Edwin Showell, Charles
Showell, and John Empson at the Office of the Commissioners of Patents on
the 22nd June 1880.
EDWIN SHOWELL and CHARLES SHOWELL, of the Firm of Edwin Showell and
Sons, of Birmingham, in the County of Warwick, Brassfounders, and JOHN
EMPSON, of Birmingham aforesaid, Tool Maker. "IMPROVEMENTS IN RACK PULLEYS
FOR THE CORDS OF WINDOW AND OTHER BLINDS AND THE CORDS OF OTHER
ARTICLES."
Our Invention consists in constructing and arranging the parts of the said rack
pulleys in the following manner :-
We make the body or fixed part of the rack pulley from sheet metal, the teeth
of the rack being formed from the sheet metal by dies and pressure. Or the body
and teeth of the rack may be made by casting.
The sliding part or pulley carrier is constructed as follows:-The pulley works
on an axis the front end of which terminates in a thumb plato. The rear part of
the axis, or that part which works in the slot in front of the body or fixed part,
is rectangular in cross section, and fits the slot in which it slides.
To the end of the rear part of the axis a long rectangular plate or strip of metal
is rivetted, the two vertical edges of the upper part of the said plate or strip being
turned nearly at right angles to the body of the plate or strip. The top edge of
the said plate is bont at an angle of forty five degrees, and constitutes a tooth or
catch which engages in the teeth of the rack in the back of the body or frame of
the rack pulley. The lower part of the said plate is of less breadth than the upper
part, and is turned up or folded on the upper part so as to lie in an inclined
position between the said upper part and the pulley, the axis of the pulley passing
through a slot in the turned up part of the plate. The said turned up part of the

page_text: plate constitutes a spring, which when the slide or pulley carrier is inserted in the
fixed body of the rack presses the tooth or catch on the top of the slide against
the rack teeth. When the slide is depressed it tooths or catch slides over the
inclined faces of the teeth of the rack, and prevents the return or ascending motion
of the slide or pulley carrier by engaging under the horizontal face of the tooth it
has last passed.
When it is desired to raise the slide or pulley carrier it is only necessary to
draw the upper part of the thumb plate forward or from the body of the rack.
The tooth or catch of the slide is thereby released from the rack and the slide can
be raised. By loosing the thumb plate the spring causes the tooth or catch to
engage again in the rack, and the ascent of the slide is prevented.
The turning of the vertical edges of the upper part of the slide causes the slide
to fit the fixed body of the rack accurately and to work smoothly therein.
Rack pulleys made according to our Invention may be used with the cords of
the rollers of maps and plans and for the cords of other articles.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Edwin Showell, Charles Showell, and John Empson in the Great
Seal Patent Office on the 3rd December 1880.
EDWIN SHOWELL and CHARLES SHOWELL, of the Firm of Edwin Showell. and
Sons, of Birmingham, in the County of Warwick, Brassfounders, and JOHN
EMPSON, of Birmingham aforesaid, Tool Maker. "IMPROVEMENTS IN RACK PULLEYS.
. FOR THE CORDS OF WINDOW AND OTHER BLINDS AND THE CORDS OF OTHER
ARTICLES."
Our Invention consists in constructing and arranging the parts of the said rack
pulleys in the following manner :-
We make the body or fixed part of the rack pulley from sheet metal, the teeth
of the rack being formed from the sheet metal by dies and pressure. Or the body
and teeth of the rack may be made by casting.
The sliding part or pulley carrier is constructed as follows:- -The pulley works
on an axis, the front end of which terminates in a thumb plate. The rear part of
the axis, or that part which works in the slot in front of the body or fixed part,
is rectangular in cross section, and fits the slot in which it slides.
To the end of the rear part of the axis a long rectangular plate or strip of
metal is rivetted, the two vertical edges of the upper part of the said plate or
strip being turned nearly at right angles to the body of the plate or strip. The top
edge of the said plate is bent at an angle of forty five degrees, and constitutes a
tooth or catch which engages in the teeth of the rack in the back of the body or
framo of the rack pulley. The lower part of the said plate is of less breadth than
the upper part, and is turned up or folded on the upper part so as to lie in an

page_text: inclined position between the said upper part and the pulley, the axis of the pulley
passing through a slot in the turned up part of the plate. The said turned up part
of the plate constitutes a spring, which when the slide or pulley carrier is inserted
in the fixed body of the rack presses the tooth or catch on the top of the slide
against the rack teeth.
When the slide is depressed its tooth or catch slides over the inclined faces of the
teeth of the rack, and prevents the return or ascending motion of the slide or pulley
carrier by engaging under the horizontal face of the tooth it has last passed. When
it is desired to raise the slide or pulley carrier it is only necessary to draw the
upper part of the thumb plate forward or from the body of the rack. The tooth or
catch of the slide is thereby released from the rack and the slide can be raised.
By loosing the thumb plate the spring causes the tooth or catch to engage again
in the rack, and the ascent of the slide is prevented. The turning of the vertical
edges of the upper part of the slide causes the slide to fit the fixed body of the rack
accurately and to work smoothly therein.
Rack pulleys made according to our Invention may be used with the cords
of the pulleys or rollers of maps and plans and with the cords of other articles.
We will now proceed to describe with reference to the accompanying Drawing
the manner in which our Invention is to be performed.
Figures 1 and 2 represent longitudinal sections of a rack pulley constructed
according to our Invention, the slide or pulley carrier being engaged with the rack
teeth in Figure 1, and disengaged therefrom in Figure 2.
Figure 3 is a front elevation of the rack pulley, partly in vertical section, and
Figure 4 is a cross section of the same; Figure 5 represents the slide or pulley
carrier detached from the body or frame; Figure 6 represents the plate, the tooth
or catch, the spring, and the vertical bearing edges of the pulley carrier without
the pulley and thumb plate; Figure 7 represents the blank or strip from which
the catch plate, its catch and spring, and the vertical bearing edges are made; and
Figure 8 represents the said blank or strip partly shaped or bent.
The same letters of reference indicate the same parts in the several Figures of
the Drawing.
a is the body or fixed part of the rack pulley having in its back plate the ordinary
rack teeth b, with which the tooth or catch of the slide or pulley carrier engages.
The front of the said body a is provided with the usual longitudinal slot or
opening c in which the axis of the pulley carrier slides. The body a and rack
teeth b may be made from sheet metal by dies and pressure or by casting. d is
the pulley of the slide or pulley carrier working on the axis e, the front end of
which terminates in a thumb plate f. The rear part es of the axis e is rectangular
in cross section and slides in the slot c in the front of the fixed part a (see Figures 4
and 5.)
To the end of the rear part e³ of the axis e the catch plate his rivetted, the said
plate being at its back a spring i mado in one piece with the said plate. The
spring i has a long slot in it which works upon the rear part 2 of the pulley
axis. The two vertical edges of the catch plate hare turned or bent nearly at
right angles to the said plate. These bent parts are marked 1, l, and constitute
bearing edges for the pulley carrier, as herein after explained. The top edge of
the plate his bent at the angle represented, and constitutes a tooth or catch m
which engages with the rack teeth 6 at the back of the fixed body a. The parts
h, i, l, and m are made from the blank represented in Figure 7, the side bearing
parts 1,, being made from the broad parts 12, 13, of the blank, and the tooth or
catch m from the part m. The lower part of the blank is of less breadth than
the upper part 2, and from the said part the spring i is made. The part i³ is
first turned up or folded in the manner represented in Figure 8, and afterwards
bent back into the inclined position shown in Figure 6 so as to form the spring i,
the said spring being situated at the back of the catch plate. The upper half of
the blank is pierced at n for the axis of the pulley carrier to pass through, and
the lower half of the blank is pierced at k for the rear rectangular part of the
•

page_text: axis to pass through. When the axis e carrying the pulley and thumb plate is
rivetted to the catch plate h tho spring i at its back is situated between the said
plate and the inner face of tho pulley d, as seen in Figure 5. On placing the slide
or pulley carrier in the fixed body a of the rack pulley the spring i bears against
the front of the said body a (see Figure 4), and presses the tooth or catch m at the
top of the slide against tho rack teeth b, as represented in Figure 1. When the
slide is depressed in the body a its tooth or catch on slides over the inclined faces
of the rack teeth b, and the return or ascending motion of the slide is prevented
by the said tooth or catch m engaging with one of the rack teeth b in the manner
represented in Figure 1. When it is wished to raise the slide or pulley carrier in
the fixed body a the upper part of the thumb plato fis drawn forward or from the
body a, as illustrated in Figure 2. The tooth or catch m is thereby released from
the rack tooth with which it was engaged, the catch plate m fixed to the axis c
being brought parallel to the spring i. The slide or pulley carrier can now bo
raised in the body a. After the position of the slide has been adjusted the thumb
plate fis loosed, when the spring i,causes the tooth or catch m to engage again
with the rack teeth b and fix the slide in its adjusted position.
The manner in which the turned vertical edges 1, 1, of the slide or pulley carrier
fit and bear against the fixed body a of the rack pulley will be best understood by
an examination of Figure 4. By the use of the said vertical bearing edges L, l, of
the slide the latter is made to fit the body a accurately and to work smoothly
therein,
Having now described the nature of our Invention, and the manner in which
the same is to be performed, we wish it to be understood that we claim as our
Invention of "Improvements in Rack Pulleys for the Cords of Window and other
Blinds and the Cords of other Articles,”.
1
The combination with the bodies of rack pullies having rack teeth on their backs
of a slide or pulley carrier constructed in the manner herein before described and
illustrated in the accompanying Drawing, that is to say, a slide or pulley carrier
consisting of a catch plate h having at its back a spring, the top of the said plato h
being furnished with a tooth or catch m for engaging with the rack teeth, and at
its sides or vertical edges with bearing parts 7, l, for causing the slide or pulley
carrier to accurately fit and work smoothly in the body of the rack pulley, the
axis carrying the pulley d and thumb plato ƒ being connected to the catch plate h
and the catch of the said plate being engaged with and disengaged from tho rack
teeth, substantially as described and illustrated.
In witness whereof, I, the said Charles Showell, have hereunto set my hand
and seal, this Second day of December, in the year of our. Lord Oue
thousand eight hundred and oighty.