Improvements in Flexible Driving Shafts.
Year: 1894

page_text: Date of Application, 6th July, 1894
Complete Specification Left, 29th Mar., 1895-Accepted, 4th May, 1895
PROVISIONAL SPECIFICATION.
Improvements in Flexible Driving Shafts.
I JAMES YATE JOHNSON of 47 Lincoln's Inn Fields in the County of London
Gentleman do hereby declare the nature of this invention (which has been
communicated to me from abroad by Charles Jules Fravega and Armand Janet
both of 8 Chaussée D'Antin Paris in the Republic of France) to be as
follows:-
This invention relates to flexible shafts serving for the transmission of rotary
motion produced by an engine (stationed permanently or temporarily at a
predetermined place) to mechanism whatever its situation or direction of motion.
The flexible shafts hitherto used have cousisted of suitably arranged metal
spirals while the main part of the improved flexible shaft constituting the present
based upon the
invention, is a chain the operation of which as a flexible shaft,
principle that if a twisting or rotary movement be imparted to one end of a chain,
the other end will tend to follow the direction of this movement and the chain may
consequently be utilised as a means of transmission of rotary motion, provided it be
prevented from forming loops or "knots" by winding about itself.
This end is attained according to the present invention by either employing a
suitably fitted chain or by adding to an ordinary chain, various parts or attach-
ments, such as are hereinafter described, so as to make it fit for use as a flexible
shaft.
In the former case the flexible driving shaft constructed according to this
invention is characterized by the following peculiarity; the successive links of the
chain may be of a shape which may vary according to circumstances, but which
should be such that when these consecutive links are fixed or jointed together,
their hinge-pins are arranged alternately at right angles to each other. The shape
of the links is such that they present abutting or contact surfaces to each other
which surfaces meet at predetermined times so as to limit the amplitude of the
angle between adjacent links.
By such means the flexible shaft or chain can assume the general outline of a
double curve without becoming looped or wound about itself though the radius of
the curve should at no point thereof exceed the minimum compatible with the
proper operation of the driving shaft in practice.
One form of link may be taken to be formed from a section or length of a bar,
supposed to have been originally of circular shape in section, but cut or hammered
down so as to present, in two planes at right angles to each other, a tongue forming
the male part of the hinge and perforated at one end while at the other end of the
link there is the corresponding groove or female part of the hinge formed by two
cheeks having perforations coinciding in such a manner that one of them forms an
extension or continuation of the other.
The male portion of one of the links engages in the female portion of the next
link and the joint is completed by a binge-pin or bolt riveted or otherwise secured
at its two ends or retained in place by other suitable means so that when the chain
is fitted together its consecutive links can turn about their axes alternately at right
angles to each other.

page_text: The tongue and each of the cheeks terminate in plane inclines, symmetrical in
relation to the two diametrically opposite planes of the link. When the angle of
inclination either at one or the other side of any one link in relation to the next
link attains certain predetermined proportions the respective edges of the tongue of
the male part and those of the checks of the female part of the hinge meet
respectively the bottom of the groove between the two cheeks and the two plane
surfaces contiguous to the tongue. When this position is reached the angle of
inclination cannot be further increased and the consecutive links are thus prevented
from forming too large an angle between them as an unduly enlarged angle would
interfere with the proper operation of the flexible shaft in practice and be
detrimental to the useful effect of the trausmission.
The chains or flexible shafts of this description owing to the cylindrical shape of
the links may be advantageously surrounded with a tubular casc or sheath made of
a suitable fabric or flexible or elastic material such as india rubber, for example,
capable of protecting them from dust, and of deadening any shocks which they
may sustain, while imparting to the whole the outward appearance of an ordinary
flexible shaft. When it is preferred to dispense with this casing the chain may
consist of prismatic links constructed and arranged to operate in the same manuer
as the links herein before described but instead of being formed from a cylindrical
bar or rod they may be formed from a prismatic bar of square or rectangular shape
in section.
In both the forms of links above described the bolts only serve to prevent the
links from becoming disconnected from each other, without however, subjecting
them to any strain in consequence of the twist imparted to the chain, inasmuch as
each of the tongues or male parts of the hinge is snugly fitted between the two
cheeks.constituting the female portion of the hinge which sustain any strain that
may be produced by twisting the chain. This is an important advantage ensuring
great durability to the chain; for while the mutual pressure exercised by the respective
contact surfaces of adjacent links is distributed over a comparatively large surface,
the bolts on the other hand, are subjected to a very slight strain, and the wear both
of these boits, and of the links themselves, is reduced to a minimum. These facts
are sufficiently important to outweigh any consideration of cost in those cases
where the object in view is to procure a durable device and to transmit considerable
power. Where, however the Hexible shaft is intended to transmit but small power
it may be sufficient to employ a chain formed of links having a prismatic body, but
including no female portion. They are joined together by means of bolts or pins
traversing the projections the thickness of each of which is equal to one half of the
body of a link, the angle of inclination of every two consecutive links being limited
in the same manner as in the preceding form of links.
It will be readily seen that the construction of these links is extremely simple
and cheap but the bolts in this case have to resist the strain resulting from the
tendency of the contact surfaces of the links to move away from each other, and
they are also more subject to wear. Where it is desired to surround this chain
with a protecting case, these links may be constructed with a cylindrical body
fitting the shape of the case more exactly.
We wish it to be distinctly understood that we do not limit ourselves to the
forms described as any type of chain with links suitably fitted together and
answering the same purpose may be used, as will be readily understood.
In some
cases an ordinary chain may be used, which may be rendered incapable of being
wound about itself and forming loops, by surrounding it with suitable filling
material imparting to the whole the appearance of a cylindrical or prismatic rod,
the chain forming the core.
To form this filling, and also the casings of the chains hereiubefore described,
bands, strips, cords or threads of any suitable material such as leather, india-rubber
or the like, wire laces or braids of suitable textile material, hemp, oakum, or any
other fibrous material either pure or mixed with other substances capable of
improving its quality, or of making it more durable, may be employed. According

page_text: to the nature and shape of the material employed, this filling may either be entirely
exposed or it may be wholly or partly covered by the casing or the bands or strips
so as to be thereby retained on the chain.
Dated this 6th day of July 1894.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, Agents.
Improvements in Flexible Driving Shafts.
I, JAMES YATE JOHNSON, of 47 Lincoln's Inn Fields, in the County of
London, Gentleman, do hereby declare the nature of this invention (which has
been communicated to me from abroad by Charles Jules Fravega and Armand
Janet both of 58 Chaussée D'Antin Paris in the Republic of France) 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 flexible shafts serving for the transmission of rotary
motion produced by an engine (stationed permanently or temporarily at a
predetermined place) to mechanism, whatever its situation or direction of motion.
The flexible shafts hitherto used have consisted of suitably arranged metal
spirals, while the main part of the improved flexible shaft, constituting the present
invention, is a chain the operation of which as a flexible shaft, is based upon the
principle, that if a twisting or rotary movement be imparted to one end of a chain,
the other end will tend to follow the direction of this movement, and the chain may
consequently be utilised as a means of transmission of rotary motion, provided it be
prevented from forming loops or knots by winding about itself.
This end is attained according to the present invention by either employing a
suitably fitted chain or by adding to an ordinary chain various parts or attach-
ments such as are hereinafter described, so as to make it fit for use as a flexible
shaft.
In the former case the flexible driving shaft constructed according to this
invention is characterised by the following peculiarity; the successive links of the
chain may be of a shape which may vary according to circumstances, but which
should be such that, when these consecutive links are fixed or jointed together,
their hinge pins are arranged alternately at right angles to each other. The shape
of the links is such that they present abutting or contact surfaces to each other, which
surfaces meet at predetermined times so as to limit the amplitude of the angle
between adjacent links.
By such means the flexible shaft or chain, can assume the general outline of
a double curve without becoming looped or wound about itself, though the radius
of the curve should at no point thereof exceed the minimum compatible with the
proper operation of the driving shaft in practice.
I will describe the invention with reference to the accompanying drawings in
which
Figures 1 to 4 represent one form of flexible driving shaft or chain constructed
according to this invention and having cylindrical links, the figures being
respectively elevations at right angles to each other and two perspective views,
also at right angles to each other.
Figures 5 to 8 are similar views representing a modified form of the link shewn
in the preceding figures. This form of link shall be herein referred to as a
prismatic link.

page_text: Figure 9 is a front view of a length of chain consisting of four links, constructed
according to this invention, the two extreme ones of which have reached their limit
of inclination or their extreme angular position in relation to the two central links
which form between them an intermediate angle.
Figure 10 is a top view of the same segment.
Figures 11 to 14 are respectively two longitudinal elevations at right nugles to
each other and two perspective views also at right angles to each other showing a
simplified form of link more especially intended for shafts which have no considerable
strains to transmit.
Like reference numbers and letters desiguate corresponding parts in all the
figures.
The link shewn in the Figures 1 to 4 may be taken to be formed from a section
or length 1 of a bar, supposed to have been originally of circular shape in section,
but cut or hammered down so as to present in two planes at right angles to each
other, a tongue forming the male part of the hinge 2, and perforated at one end, as
at 3; while at the other end of the link there is the corresponding groove or
female part of the hinge formed by two cheeks 4, having perforations 5, coinciding
in such a manner that one of them forms an extension or continuation of the
other.
The male portion of one of the links engages in the female portion of the next
link and the joint is completed by a hinge pin or bolt rivetted or otherwise secured
at its two ends or retained in place by other suitable means, so that when the chain
is fitted together its consecutive links can turn about their axes such as X X
and Y Y, alternately, at right angles to each other.
The tongue 2 and each of the cheeks 5 as shewn in the drawings terminate in
inclined planes 7, 8, and 7, 9, symmetrical in relation to the two diametrically
opposite planes of the link. When the angle of inclination either at one or the
other side of any one link in relation to the next link attains certain predetermined
proportions the respective edges 8 and 9 of the tongue 2 of the male part and those
of the cheeks 4, of the female part of the hinge meet respectively the bottom 10 of
the groove between the two cheeks and the two plane surfaces 11 and 12 contiguous
to the tongue 2. When this position is reached, the angle of inclination cannot be
further increased and the consecutive links are thus prevented from forming too
large an angle between them as an unduly enlarged angle would interfere with the
proper operation of the flexible shaft in practice and be detrimental to the useful
effect of the transmission.
The chains or flexible shafts of this description owing to the cylindrical shape of
the links may be advantageously surrounded with a tubular case or sheath made of
a suitable fabric or flexible or elastic material, such as india-rubber, for example,
capable of protecting them from dust, and of deadening any shocks which they may
sustain, while imparting to the whole the outward appearance of an ordinary
flexible shaft. When it is preferred to dispense with this casing, the chain may
consist of prismatic links such as are shown in Figures 5 to 10.
These links are constructed and arranged to operate in the same manner as the
links hereinbefore described but instead of being formed from a cylindrical bar or
rod they may be formed from a prismatic bar of square or rectangular shape in
section. A chain thus formed of links connected together by bolts 6, will present
the appearance shewn in Figures 9 and 10, which figures clearly illustrate the
manner in which, in this form of chain, the angle of inclination of one link to the
other is limited.
It will be seen that in both the forms of links above described the bolts 6 only
serve to prevent the links from becoming disconnected from cach other, without,
however, subjecting them to any strain in consequence of the twist imparted to the
chain, inasmuch as each of the tongues or male parts of the hinge is snugly fitted
between the two cheeks constituting the female portion of the hinge which sustain
any strain that may be produced by twisting the chain.

page_text: This is an important advantage ensuring great durability to the chain; for, while
the mutual pressure exercised by the respective contact surfaces of adjacent links is
distributed over a comparatively large surface, the bolts, on the other hand, are
subjected to a very slight strain, and the wear both of these bolts, and of the links
themselves, is reduced to a minimum. These facts are sufficiently important to
outweigh any consideration of cost in those cases where the object in view is to
procure a durable device and to transmit considerable power.
Where, however, the flexible shaft is intended to transmit but small power it may
be sufficient to employ a chain formed of links constructed in the manner illustrated
in Figures, 11 to 14, the arrangement being, in that case, considerably simplified.
These links, like those shown in Figures 5 to 10, have a prismatic body but include
no female portion. They are joined together by means of boits or pins traversing
the projections 2 the thickness of each of which is equal to one half of the body of
a link, the angle of inclination of every two consecutive links being limited in the
same manner as in the preceding forms of links.
It will be readily seen that the construction of these links is extremely simple
and cheap but the bolts in this case have to resist the strain resulting from the
tendency of the contact surfaces of the links to move away from each other, and
they are also more subject to wear. Where it is desired to surround this chain
with a protecting case, these links, like those shown in Figs. 1 to 4, may be
constructed with a cylindrical body fitting the shape of the case more exactly,
This last type of cylindrical link has not been shown in the drawings, to avoid
complication, but it will be readily understood from the description of the last form
of link.
This invention is not limited to the forms described as any type of chain with
links suitably fitted together and answering the same purpose may be used, as will
be readily understood. In some cases au ordinary chain may be used, which may
be rendered incapable of being wound about itself and forming loops, by surrounding
it with suitable filling material imparting to the whole the appearance of a cylindrical
or prismatic rod, the chain forming the core.
To form this filling, and also the casings of the chains hereinbefore described,
bands, strips, cords or threads of any suitable material such as leather, india-rubber,
or the like, wire laces, or braids of suitable textile material, hemp, oakum, or any
other fibrous material either pure or mixed with other substances capable of
improving its quality, or of making it more durable, may be employed.
According to the nature and shape of the material employed, this filling may
either be entirely exposed, or it may be wholly or partly covered by the casing or
the bands or strips so as to be thereby retained ou the chain.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed 1 declare that what I
claim is :-
1. A flexible shaft for the transmission of motive power consisting of a chain the
consecutive links of which are of a shape variable according to circumstances but
such that the consecutive links may be connected together by a hinge pin, the
respective axes of the hinges being alternately at right angles to each other, and
the shape of the said links being so devised as to provide them with abutting or
contact surfaces, arranged to meet at the moment when the extreme limit of the
angle which every two adjacent links should be capable of forming is attained
substantially as and for the purpose set forth.
2. The several forms of links fulfilling the conditions above stated, substantially
as described with reference to Figs. 1 to 4, Figs. 5 to 10, and Figs. 11 to 14 of the
accompanying drawings.
3. Adapting an ordinary chain so as to be capable of serving the purpose of a
flexible driving or transmission shaft by surrounding it with a suitable filling so as
to prevent its winding about itself and forming loops, the said filling being so fitted

page_text: as to impart to the chain the shape of a prismatic or cylindrical rod, the core of
which is constituted by the said chain, the said filling being formed of one or more
suitable substances such as leather, india rubber, or the like as aforesaid, substan-
tially as herein before described.
Dated this 29th day of March 1895
JOHNSONS & WILLCOX,
Agents.