IMPROVEMENTS IN VARIABLE SPEED PULLIES AND BANDS THEREFOR
Year: 1879

page_text: LETTERS PATENT to Bewicke Blackburn and Alexander Bewicke Blackburn,
both of No. 14, Victoria Road, Kensington, in the County of Middlesex, for
the Invention of "IMPROVEMENTS IN VARIABLE SPEED PULLIES AND BANDS
THEREFOR
"
Sealed the 16th December 1879, and dated the 19th June 1879.
PROVISIONAL SPECIFICATION left by the said Bewicke Blackburn and
Alexander Bewicke Blackburn at the Office of the Commissioners of Patents
on the 19th June 1879.
BEWICKE BLACKBURN and ALEXANDER BEWICKE BLACKBURN, both of No. 14,
Victoria Road, Kensington, in the County of Middlesex. "IMPROVEMENTS IN
VARIABLE SPEED PULLIES AND BANDS THEREFOR."
Our Invention relates to means of varying the speed of shafting driven by bands,
for which purpose we employ a construction and arrangement of pullies and bands
as we will now describe. We construct a pulley in halves, each half shaped as a
truncated cone, so that when the halves are placed on a shaft or axis, face to face, a
deep V groove is presented between them. One of the halves is fixed on the shaft,
the other half is fitted thereon with a feather, so that it must revolve with the
shaft, but can be slid nearer to or farther from the fixed half. For working in the
groove of the pulley we provide a flexible band, which is sufficiently wide to fill
the outer part of the V groove when the halves of the pulley are nearest to one
another, and which, when these halves are set wider apart, fills a part of the V groove
nearer to the axis, so that according as the halves are set nearer to or further from
one another the band acts at a greater or less radius. Either or both of two pullies
connected by a band may be constructed as above described, the moveable half
pulley in either case being arranged to be shifted by a fork lever or otherwise, or
being pressed by a spring permitting by its elasticity certain yield of the moveable
half to suit a variable length or strain of the band. When only one or two pullies
is variable the band may be kept tight by a tightening pulley. When both pullies
are variable only one of them may be arranged to be varied by hand, the other
having its halves pressed together by a spring, so that their relative position is
altered by the action of the band when the former pulley is varied. Thus when the
halves of the one pulley are shifted nearer together, causing the band to act at a
greater radius on it, the halves of the other pulley are by the drawing in of the
band forced further apart so that the band acts thereon at a less radius, and thus
the relative speed of the two pullies is altered by the alteration of one of them.

page_text: Machinery driven by pullies of the kind described above may be stopped by intro-
ducing between the conical halves of one of the pullies a roller or flat pulley loose
on the shaft, so that when the halves are so far separated that the band is no longer
supported on their conical surfaces, it bears on the loose pulley or roller which can
revolve without driving or being driven by the shaft. The wide but flexible band
which we employ for working on pullies of the kind described consists internally
of a strong flexible core, which may be a pitch or other chain, a cord, rope, or
catgut band, or a number of cords or wires laid side by side or twined together.
On this core are strung side by side a number of pieces of leather or other some-
what yielding material, which may be of disc or oval shape, but which are pre-
ferably made with oblique sides to fit the obliquity of the sides of the V groove of
the pulley. These pieces being cut or punched out to the desired shape, each with
a hole in its middle to fit the core can be strung on the core before its ends are
joined together. It is, however, of advantage to cut in each piece a slit from the
hole to the outer edge, so that the pieces can be opened out and passed on to the
core, or any piece can be taken off when worn and replaced by a fresh piece with-
out undoing the junction of the core. The slit moreover permits the pieces to be
compressed and clamped on the core by the lateral pressure of the cone surfaces on
which the band bears. When we employ a pitch chain as the core of the band the
width and oblique shape to fit the V groove between the halves of the pulley may
be obtained by attaching to the links of the chain strips of metal bent to the
required shape, and secured to the chain by rivets, which may be those that join
the links of the chain.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Bewicke Blackburn and Alexander Bewicke Blackburn in the Great
Seal Patent Office on the 18th December 1879.
BEWICKE BLACKBURN and ALEXANDER BEWICKE BLACKBURN, both of No. 14,
Victoria Road, Kensington, in the County of Middlesex. "IMPROVEMENTS IN
VARIABLE SPEED PULLIES AND BANDS THEREFOR."
Our Invention relates to means of varying the speed of shafting driven by bands,
for which purpose we employ a construction and arrangement of pullies and bands,
as we will now describe. We construct a pulley in halves, each half shaped as a
truncated cone, so that when the halves are placed on a shaft or axis, face to face, a
deep V groove is presented between them. One of the halves is fixed on the shaft,
the other half is fitted thereon with a feather, so that it must revolve with the shaft,
but can be slid nearer to or farther from the fixed half. For working in the groove
of the pulley we provide a flexible band, which is sufficiently wide to fill the outer
part of the V groove when the halves of the pulley are nearest to one another, and
which, when these halves are set wider apart fills a part of the V groove nearer to
the axis, so that according as the halves are set nearer to or farther from one
another, the band acts at a greater or less radius. Either or both of two pullies
connected by a band may be constructed as above described, the moveable half
pulley in either case being arranged to be shifted by a fork lever or otherwise, or
being pressed by a spring permitting by its elasticity certain yield of the moveable
half to suit a variable length or strain of the band. When only one of two pullies

page_text: is variable the band may be kept tight by a tightening pulley. When both pullies
are variable, only one of them may be arranged to be varied by hand, the other
having its halves pressed together by a spring so that their relative position is
altered by the action of the band when the former pulley is varied. Thus when
the halves of the one pulley are shifted nearer together, causing the band to act at
a greater radius on it, the halves of the other pulley are by the drawing in of the
band forced farther apart, so that the band acts thereon at a less radius, and thus
the relative speed of the two pullies is altered by the alteration of one of them.
Machinery driven by pullies of the kind described above may be stopped by intro-
ducing between the conical halves of one of the pullies a roller or flat pulley loose
on the shaft, so that when the halves are so far separated that the band is no longer
supported on their conical surfaces, it bears on the loose pulley or roller, which can
revolve without driving or being driven by the shaft. The wide but flexible
band which we employ for working on pullies of the kind described consists
internally of a strong flexible core, which may be a pitch or other chain, a cord,
rope, or catgut band, or a number of cords or wires laid side by side or twined
together. On this core are strung, side by side, a number of pieces of leather or
other somewhat yielding material, which may be of disc or oval shape, but which
are preferably made with oblique sides to fit the obliquity of the sides of the
V groove of the pulley. These pieces being cut or punched out to the desired
shape, each with a hole in its middle to fit the core, can be strung on the core before
its ends are joined together. It is, however, of advantage to cut. in each piece a
slit from the hole to the outer edge, so that the pieces can be opened out and
passed on to the core, or any piece can be taken off when worn and replaced by a fresh
piece without undoing the junction of the core. The slit moreover permits the
pieces to be compressed and clamped on the core by the lateral pressure of the cone
surfaces on which the band bears. When we employ a pitch chain as the core of
the band the width and oblique shape to fit the V groove between the halves of
the pulley may be obtained by attaching to the links of the chain strips of metal
bent to the required shape and secured to the chain by rivets, which may be those
that in the 1-L
Fig. 1 is a section, and Fig. 2 an elevation of a pair of variable speed pullies
with their connecting band according to our Invention, Figs. 3 and 4 shewing to
an enlarged scale the band in transverse section and a part thereof in longitudinal
section. Each pulley consists of two conical parts F and G, the one part F being
fixed on the shaft, and the other part G fitted with a feather thereon so that it can
slide on, but must revolve with the shaft. The part G is in each case pressed
towards the other part F by a helical spring H, but, in either pulley or both, the
part G may be moved towards F, or away from it, by means of a fork lever E
engaging with a ring fitting in a groove as arranged usually for moving clutches.
The band consists of a pitch chain K (or it might be a rope or catgut), on the links
of which are strung trapezoidal pieces L of leather or other somewhat yielding
material, their sides having the same obliquity as the conical surfaces of the part F
and G of the pullies, so that they fit into the V groove formed between those sur-
faces. The pieces L may be strung on the core K before joining its ends. It is
however, advantageous to slit each of the pieces L by a cut L, extending from the
central hole to the outside, so that any of the pieces can be put on the core or taken
off from it by opening it at the slit, which, when the band is in action, is prevented
from opening by the pressure to which the piece L is subjected between the conical
faces of the pullies. When in either of the pullies the part G is slid towards the
other part F the band is caused to take a position farther from the centre of that
pulley, and having thus to extend over a greater circumference is subjected to a
tension which causes it to take a position nearer the centre of the other pulley,
wedging its part G away from F in opposition to the spring H. Or again, when

page_text: the part G of either pulley is moved away from F so as to permit the band to take
a position nearer to the centre of that pulley, then the spring H of the other pulley
causes the part G thereof to approach the part F, so taking up the slack of the
band. According to the relation of the radial distances at which the band is thus
made to act in, the two pullies will be the relative velocities of their rotation. It
is of advantage to provide in the middle of each pulley a roller R loose on the shaft,
so that when by the widening of the V groove the band comes to bear on that
roller, its driving action on the shaft ceases, and thus the one shaft can be brought
to rest while the other continues its rotation. It is obvious that instead of helical
springs H weights or springs of other forms could be employed to press the moveable 1
parts of the pullies towards the fast parts thereof, also that such springs or weights
could be dispensed with when means are applied to slide the moveable parts of
both pullies in contrary directions. One of a pair of pullies connected by a band
with suitable tightening gear may be of fixed diameter, the other one being made
to present a variable groove, as above described.
Having thus described the nature of our Invention, and in what manner the
same is to be performed, we claim,—
First. The construction of variable speed pulley in two conical parts, the distance
of which can be varied so as to admit a band of constant width in the groove
btween them at variable distance from the centre of the pulley, substantially |
as berein described.
Second. The use for connecting variable speed pullies, such as are referred to in
the preceding claim, of a band consisting of a chain or other flexible core on which
are fixed, side by side, a number of pieces of leather or other somewhat yielding
material shaped to fit or bear against the conical surfaces presented in the grooves
of the pullies, substantially as herein described.
Third. Subjecting the moveable parts of pullies such as are referred to in the
first claim to spring or other yielding pressure towards the fixed parts, substantially
as and for the purposes herein set forth.
In witness whereof, I, the said Alexander Bewicke Blackburn, have hereunto
set my hand and seal, this Seventeenth day of December, in the year of our
Lord One thousand eight hundred and seventy nine.
ALEYB R BLACKBURN (Le)