IMPROVED MEANS OR APPARATUS FOR TRANSMITTING POWER BY BELTS AND PULLEYS to be as follows:
Year: 1884

page_text: I, CHARLES DENTON ABEL of No 28 Southampton Buildings, Chancery Lane,
in the county of Middlesex, Consulting Engineer and Patent Agent do hereby
declare the nature of the said invention for "IMPROVED MEANS OR APPARATUS
FOR TRANSMITTING POWER BY BELTS AND PULLEYS to be as follows:-
"
This invention relates to improved means or apparatus for transmitting power
by belts and pulleys, whereby either belts of smaller width than hitherto employed
may be used for transmitting the same power, or greater power be transmitted by
belts of the ordinary width. It also affords an easy means for preventing belts
from slipping and for interrupting the transmission of power instantaneously.
For the purpose of thoroughly explaining the substance of this invention, I will
shortly refer to the present mode of transmitting power by belting.
In order to transmit a force, that is, a given number of foot-pounds divided by
the velocity of the belt in feet, from the circumference of one pulley to the
circumference of another one, the belt must have a tension great enough to create
the necessary amount of friction on the pulley, without which the belt would slip.
This tension is greater than the force transmitted by the belt, and its amount
varies with the length of that part of the circumference of the pulley that is in
contact with the belt. This length is equal to half the circumference (fig. 1) if
both pulleys are of equal diameter, and may vary from 0·1 to about 0·7 of the whole
circumference, according to the difference of diameters (fig 2) and distance between
the pulleys. The smaller the length of the arc in contact with the belt on the
pulley the greater must be the tension in order to prevent the belt from slipping
on the smaller pulley.
If A is the driving and B the driven pulley; the tension t of the part go of
the belt is much smaller than the tension T of df, but the thickness and width of
the belt must be proportioned to the greater tension T.
According to the present invention, increased friction is obtained between the
pulley and the driving belt by the use of a pressing roller which is made to press
the belt against the pulley at any point where the two are in contact, by which

page_text: means, as the requisite friction no longer depends upon the strain on the belt, such
strain, and consequently the section of the belt, will only require to be proportional
to the force to be transmitted, thus resulting in a proportionate economy in the
size of belt required for transmitting a certain power.
The greatest economy is obtained if the roller is placed on the driving pulley, at
or near to that point where the belt leaves it, and on the driven pulley at or near
to the point where the belt meets its circumference.
Fig. 3 of the annexed drawings is a diagram shewing this arrangement; fig 4 is
& side view of one form of the pressure roller; fig. 5 is a front view of same,
fig. 6 is a transverse section on the line A-B (fig 4); fig. 7 a transverse section of
the roller used for transmission by cords, ropes, and the like.
The roller C runs in bearings D fixed to the crank lever E, pivotted at a.
A spring F, placed at any point of the lever, presses the lever and roller against
the belt and creates friction between the latter and the pulley. Once the belt is
sufficiently jammed at that one point, it will not slip.
The roller may be pressed against the pulley by means of a weight or a spring,
but preferably springs are to be used, because they give a smoother motion.
Weights produce a hammering action and destroy the belt if it has not the same
thickness throughout.
The rollers may be made of wood or metal and be-lined-or not with any softer
material, say leather or cloth, on their circumference.
In most cases, one roller is to be placed opposite the driving pulley and another
one opposite the driven pulley, but if one pulley is much smaller than the other, it
will, in many cases be found quite sufficient to use only one roller for the smaller
of the two pulleys.
The form of the lever, its point of suspension and the point which the spring or
weight acts upon, may be varied to suit the requirements of any given case, and
the lever may be done away with altogether, if the weight or spring act directly
upon the roller, as in fig. 8.
If small powers have to be transmitted, the weight of the roller itself may creato
the necessary friction without the addition of a weight or a spring.
It is to be observed that the above described roller or "belt economiser" has
nothing in common with the ordinary tension roller, used now for increasing the
tension of the belt and placed for that purpose between the pulleys. The principle
and mode of action of both kinds of rollers are diametrically opposed to each other.
The ordinary tension roller creates tension, the "economiser " does away with it; the
tension roller is placed between the pulleys; the economiser just opposite to them;
the belt with the present method must have a certain tension on the off side of the
driving pulley, whether the tension roller be used or not, but if the "economiser "
is used the belt may hang quite loosely on one side; and last, but not least, the
pressure on the journals of both pulleys is increased by the ordinary tension roller,
while it is diminished by the use of the economiser, as can be shown by a simple
calculation and actual practice.
The roller C may be lifted from its place by a rope G as shewn on Fig. 9, or by
a lever and handle, and the transmission of power be interrupted instantaneously,
because the belt or rope will slip on the pulley, as soon as the pressure of the roller
is taken off. This does away with the necessity of having a loose pulley alongside
of the fast one and causes a saving in pullies. If, however, the use of fast and
loose pullies is preferred, then the pressure roller may be applied, as shown in
Figs. 10, 11 and 12 of which Fig. 10 is a front view of this arrangement; Fig. 11
is a side view of same; and Fig. 12 is a plan partly in section.
The roller C is made to slide freely on its axis and is guided by a fork H which
embraces. also the belt I and is drawn to the right or to the left by cords J or by
other suitable means.
Fig. 13 shews a roller having the same width as the fast and loose pullies
together, which roller may be employed instead of a sliding one.

page_text: It is obvious that the arrangement shewn on Fig. 9 may be used in combination
with fast and loose pullies, because after the roller Ŏ has been lifted from the belt,
the latter may be easily shifted from the fast pulley to the loose one and vice versa.
In some cases it may be useful to increase the surface of the pulley that is in
contact with the belt in order to increase ita friction. This may be easily done by
the pressure rollers, if they are placed in such a position as to make the belt
surround more than one half of the pulley's circumference, as shown in Fig. 14.
In this case the belt may hang quite loosely between the two pressure rollers r
and 8 and the pressure on the rollers r¹ and a¹ may be made much smaller than
on the rollers 7 and 8, but still the belt will not slip owing to the greater length of
its bearing on the pulley. This arrangement has the additional advantage that it
decreases the pressure and consequently the friction of the pulley shaft journals in
their bearings, because the pressure roller will press against them in a direction
opposite to the strain of the belt, as shown in the drawing Fig. 14 by the two
arrows.
T
Figs. 15, 16, 17 and 18 show various modifications in the arrangement of the
pressure roller apparatus according to different positions of pulleys.
ABEL & IMRAY,
Agents for the Applicant,
28, Southampton Buildings,
London, W.C.

page_text: I, CHARLES DENTON ABEL of No 28 Southampton Buildings, Chancery Lane in
the county of Middlesex, Consulting Engineer and Patent Agent, do hereby
declare the nature of my said invention for "IMPROVED MEANS AND APPARATUS
FOR TRANSMITTING POWER BY BELTS AND PULLEYS " and in what manner the
same is to be performed to be particularly described and ascertained in and by the
following statement :—
This invention relates to improved means or apparatus for transmitting power by
belts and pulleys, whereby either belts of smaller width than hitherto employed
may be used for transmitting the same power, or greater power be transmitted by
belts of the ordinary width. It-also-affords-an-easy means for preventing belts
from slipping and for interrupting the transmission of power instantaneously.
For the purpose of thoroughly explaining the substance of this invention, I will
shortly refer to the present mode of transmitting power by belting.
In order to transmit a force, that is, a given number of foot-pounds, divided by
the velocity of the belt in feet from the circumference of one pulley to the circum-
ference of another one, the belt must have a tension great enough to create the
necessary amount of friction on the pulley, without which the belt would slip.
This tension is greater than the force transmitted by the belt, and its amount
varies with the length of that part of the circumference of the pulley that is in
contact with the belt. This length is equal to half the circumference (fig 1) if both
pulleys are of equal diameter, and may vary from 0.1 to about 0.7 of the whole
circumference, according to the difference of diameters (fig. 2) and distance between
the pulleys. The smaller the length of the arc in contact with the belt on the
pulley, the greater inust be the tension in order to prevent the belt from slipping
on the sinaller pulley.
If A is the driving and B the driven pulley, the tension t of the part gc of the
belt is much smaller than the tension T of df, but the thickness and width of the
belt must be proportioned to the greater tension T.
According to the present invention, increased friction is obtained between the
pulley and the driving belt by the use of a pressing roller which is made to press
the belt against the pulley at any point where the two are in contact, by which
means as the requisite friction no longer depends upon the strain on the belt, such
strain, and consequently the section of the belt will only require to be proportional
to the force to be transinitted, thus resulting in a proportionate economy in the size
of belt required for transmitting a certain power.
The greatest economy is obtained if the roller is placed on the driving pulley at
or near to that point where the belt leaves it and on the driven pulley at or near
to the point where the belt meets its circumference.
Fig. 3 of the annexed drawings is a diagram shewing this arrangement; fig. 4 is
a side view of one form of the pressure roller; fig. 5 is a front view of same, fig 0
is a transverse section on the line A-B (fig 4); fig. 7 a transverse section of the
roller used for transmission by cords, ropes, and the like.

page_text: ΤΟ ΤΟΠΟΙ Tubs in Dearings med to the crank rever pivoted し
A
spring F placed at any point of the lever presses the lever and roller against the,
belt and creates friction between the latter and the pulley. Once the belt is
sufficiently jammed at that one point, it will not slip.
The roller may be pressed against the pulley by means of a weight or a spring,
but preferably springs are to be used because they give a smoother motion. Weights
produce a hammering action and destroy the belt if it has not the same thickness
throughout.
The rollers may be made of wood or metal and be lined or not with any softer
material, say leather or cloth, on their circumference.
In most cases, one roller is to be placed opposite the driving pulley and another
one opposite the driven pulley, but if one pulley is much smaller than the other, it
will, in many cases be found quite sufficient to use only one roller for the smaller of
the two pulleys.
The form of the lever, its point of suspension and the point which the spring or
weight acts upon, may be varied to suit the requirements of any given case, and
the lever may be done away with altogether, if the weight or spring act directly
upon the roller as in fig 8.
If small powers have to be transmitted, the weight of the roller itself may create
the necessary friction without the addition of a weight or a spring.
It is to be observed that the above described roller or "belt economiser " has
nothing in common with the ordinary tension roller used now for increasing the
tension of the belt and placed for that purpose between the pulleys. The principle
and mode of action of both kinds of rollers are diametrically opposed to each
other.
The ordinary tension roller creates tension, the "economiser" does away with it,
the tension roller is placed between the pulleys, the economiser just opposite to
them; the belt with the present method must have a certain tension on the off-side
of the driving pulley, whether the tension roller be used or not, but if the economiser
is used the belt may hang quite loosely on one side; and last but not least the
pressure on the journals of both pulleys is increased by the ordinary tension roller,
while it is diminished by the use of the economiser, as can be shown by a simple
calculation and actual practice.
The roller O may be lifted from its place by a rope G as shewn on fig. 9, or by
a lover and handle, and the transmission of power be interrupted instantaneously,
because the belt or rope will slip on the pulley as soon as the pressure of the roller
is taken off. This does away with the necessity of having a loose pulley alongside
of the fast one and causes a saving in pulleys. If, however, the use of fast and
loose pulleys is preferred, then the pressure roller may be applied, as shewn in
figs. 10, 11 and 12 of which fig. 10 is a front view of this arrangement; fig 11 is a
side view of same, and fig. 12 is a plan partly in section.
The roller C is made to slide freely on its axis and is guided by a fork H
which embraces also the belt I and is drawn to the right or to the left by cords J
or by other suitable means.
Fig. 13 shews a roller having the same width as the fast and loose pulleys
together which roller may be employed instead of a sliding one.
It is obvious that the arrangement shewn in fig. 9 may be used in combination
with fast and loose pulleys, because after the roller C has been lifted from the belt,
the latter may be easily shifted from the fast pulley to the loose one and vice
versa.
In some cases, it may be useful to increase the surface of the pulley that is in
contact with the belt in order to increase its friction. This may be easily done by.
the pressure rollers, if they are placed in such a position as to make the belt
surround more than one half of the pulley's circumference as shewn in fig. 14. In
this case the belt may hang quite loosely between the two pressure rollers r¹ and 8
and the pressure on the rollers and s¹ may be made much smaller than on the
rollers 7 and 8, but still the belt will not slip owing to the greater length of its

page_text: bearing on the pulley. This arrangement has the additional advantage that it
decreases the pressure and consequently the friction of the pulley shaft journals in
their bearings, because the pressure roller will press against them in a direction
opposite to the strain of the belt, as shewn in the drawing Fig. 14 by the two
arrows.
Figs. 15, 16, 17 and 18 shew various modifications in the arrangement of the
pressure roller apparatus according to different positions of pulleys.
By the employment of pressure rollers according to the above described invention,
belts can be employed, the section of which is from 1.7 to 3.4 times smaller than
those at present used for transmitting the same power, and for high speeds a still
greater saving can be effected as with high speeds the ordinary belts require to be
made of increased width to prevent slipping.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
1, The use of a roller or rollers for pressing a driving belt against a pulley or
pullies at any point of contact of the belt with the pulley substantially as described
and for the purpose set forth.
.
2, In combination with a power-transmitting pulley and belt, a pressure roller
arranged on a bell-crank lever and pressing the belt against the pulley by the action-
of a spring applied to the longer arm of the bell crank lever, substantially as
described and shewn on the drawings..
3. In combination with the power transmitting pulley and belt, a pressure
roller pivotted to a bell crauk lever-and-arranged to be lifted from the belt,
substantially as and for the purpose described.
4, In combination with fast and loose pulleys and a power transmitting belt, a
pressure roller sliding on its axis and arranged to be shifted with the belt by means
of a guiding fork, substantially as described and shewn on the drawings.
5, In combination with fast and loose pullies and a power transmitting belt, a
pressure roller of double the width of each of the pulleys substantially as described
and shewn on the drawings.
Dated this 8th day of January 1885.