Improved Jointed or Articulated Coupling for Shafts.
Year: 1889

page_text: Date of Application, 12th Aug., 1889-Accepted, 14th Sept., 1889
COMPLETE SPECIFICATION.
Improved Jointed or Articulated Coupling for Shafts.
I MAX MANNESMANN of Romscheid Bliedinghausen Germany Engineer, do
hereby declare the nature of this Invention 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 a construction of jointed or articulated coupling for shafts
by means of which, the rotary motion of a shaft will be transmitted with a perfectly
uniform angular velocity to a second shaft situated at an angle thereto.
The action of the coupling will be most readily understood by considering its
geometrical construction and action, for which purpose I will refer to the accom-
panying drawings.
If two shafts A. A and B B' Figure I the geometrical axes of which intersect at
the point S and from an angle a with each other, are provided with arms A¹ C' and
B1 C, the geometrical axes of which form with those of the shafts A. A and B B¹
equal angles ẞ, and which during rotation always intersect at one and the same
point C, then the transmission of rotation between the two shafts A. A and B B¹
will take place at a uniform angular velocity, if the perpendiculars CD, C¹ E drawn
from the point on to the axes of A. A and B B are equal. At figure 1 of the
drawings this is the case if the points A and B are equidistant from S, as in that
case the two triangles A' C'S and BCS are similar and equal, and the line C' S
divides the angle A. S. B which the geometrical axes of A. A and B B make with
each other. The triangles ESC and D S C are consequently also similar and equal,
and the perpendiculars (D) and C' E on A. A and B B are equal to one another.
The point will always remain in the plane determined by S, symetrically situated
with regard to A. A and B B which plane is perpendicular to a plane laid through
On completion of a semi revolution the point (" arrives at C². The path
of the point C constitutes the intersection of the plane through C'S symetrical
relatively to A. A and B B with the two cones which are formed by the rotation of
the axes AC and B' C. With the proportions shewn at Figure 1
this conic section will form an ellipse, the major axis of which is 0. If ẞ he
taken so great that the arms A¹ C¹ and B¹ C¹ in passing through the plane of
these axes.
C¹ = 90
A. A' B B', are parallel to the symetrical plane S 01 (B
-
B
90
-
the conic
With
section described by the point will be a parabola, as shewn at Figure 2.
another value for the angles a and B (B) 90
В
-
2)
the conic section may be a
hyperbola as at Figure 3. Other modifications are produced if the angles a and B
are independently taken of definite values. If for example a is equal zero," the
ellipse will become a circle; if a 180° the point will describe a byperbola as at
Figure 4 and the intersection S will be infinitely removed.
=
If the angle of the cones is zero, the geometrical axes of the transmitting arms
will describe cylinders, the points A B will be infinitely removed as at Figure 5.
The point (again describes an ellipse. The connection of the transmitting arms
with the axes A. and B is then effected through intermediate parts A² A and B² B³;
the perpendiculars from the points and Con to the geometrical axes of A. A¹ B B¹
are then always equal.
i
If lastly the angle ẞ is made equal to 90° as at Figure 6, the arms will describe
plane cones which intersect on a straight line that is perpendicular to the plane
through the geometrical axes of A. A' B'B' and which passes through C.

page_text: Other modifications of the coupling are obtained if the positions of the shafts A. A'
and B B are altered. If for example the position of B B shewn at Figure 1 be
retained but that of A. A' be changed to the same side of the symetrical plane passing
through S there will obviously be nothing changed in the above described laws
of motion, if the geometrical axes of the transmitting arms remain the same.
Figure 7 shews such a modification, in which the original position of the shaft A. A¹
is shewn in dotted lines. For the connection of the transmitting arm C₁ A' with the
shaft A. A an intermediate arm A* A* is required, similar to Figure 5;
which may
have any desired shape. In this case also the perpendiculars from the point C on to
the geometrical axes A. A and B B' are equal."
If the same alteration be effected with regard to the shaft B B', as at Figure 8 the
two shafts will again be on opposite sides of the symetrical plane through S.
The arm B B need not be the same as the arm A' A', if only the position of the
geometrical axes A³ C and B C₁ corresponds to the above stated law.
The same modifications can also be effected with regard to the construction shewn
in Figures 2 to 6. Figure 9 shews for instance a modification of Figure 4 similar to
that at Figure 4, and Figure 10 a modification of Figure 5. The modification at
Figure 10 shews that the connection A A7 to the shaft A. A could be arranged in
the same manner as the connection A2 A3 to A. A².
From the above described law of motion it follows that the value of the angle ẞ as
also the absolute length of the perpendiculars CD and CE are without influence, on
the transmission. There may therefore be combined with the shafts A. and B. several
differently arranged transmitting arms of which each pair fulfils the conditions set
forth.
Figure 11 shews a coupling constructed in this manner according to the arrange-
ment at Figure 1, the transmitting arms of which form the angles ẞ and ß2 with the
shafts A. A AB and B B B³.
The distances S A' and S A8 can either be different from each other as shewn, or
not but those of the points C or C2 C3 C4 C³ from the intersection S of the geometrical
axes of the shafts must always be equal to each other.
The arrangement at Fig. 1 can also be combined with one similar to Fig. 8, in which
case the arrangement at Fig. 12 is obtained.
In a similar manner the several arms of a coupling axis can have any of the forms
of construction shewn in Figs. 1 to 10 applied thereto, provided that the two arms of
each pair are constructed according to the same system, and that all the driving axes
tend to rotate all the driven axes in the same direction.
Thus for instance Fig. 1 can be combined with Fig. 8, while a combination of Fig. 1
with Fig. 7 is not possible, because with Figs. 1, 2, 3, 5, 6, 8 the sides of the coupling
axes which are presented to each other have the same direction of motion, in a
similar manner as if the coupling axes were connected by two directly geared toothed
wheels fixed thereon, while in Figs. 7 and 10 the sides of the coupling axes BB'A' A'
and B₁ BA¹ A6, which are presented to each other, have motion in opposite directions
imparted to them, as though they were connected by two toothed wheels gearing with
an intermediate wheel.
In a similar manner more than two transmitting arms can be combined with each
shaft, and, with suitable choice of the angles ẞ, the distances of the points A¹ and B
from S and the motion of C in the symmetrical plane other couplings can be applied
in which the above stated law of motion is carried out.
In each case it is by no means necessary that the transmitting arms should all lie
in one and the same plane, as is assumed in Fig. 12; under certain circumstances it
is even necessary that this should not be the case, in particular when the coupling is
required to transmit complete revolutions, and the point C at a certain part of the
revolution is removed to an infinite distance, as at Figs. 2 to 6 and 9.
The kinematic connection of the structures which transmit the motion are given by
the laws of motion set forth. When the two transmitting arms A' C and BC Fig. 1
always intersect at one and the same point, they can be connected together by a

page_text: simple hinge joint, as shewn at Fig. 13. The joint at C¹ consists of a pair of bodies
of rotation (ie. a pivot o with an eye or socket) which allows the two arms a and b
to assume different angular positions relatively to each other.
As the distance of the point C₁ Fig. 1 from the points A and B continually
changes during the rotation of the shafts A A' and B B, it follows that the arms A¹¹
and BC must be capable of varying in length. From this it will be seen that
sockets or tubular arms a' and must be combined with the shafts A A and B B'
Fig. 13 in which the arms and 6 must be capable of sliding in the direction of the
lines AC and B'C'.
The geometrical axis of the pivot o of the joint will assume during the rotation
of the shafts A A' and B B various different positions, on which account the arms a
and must at the same time he rotatable in their sockets. During the rotation of
the two shafts therefore, the arms a and simultaneously slide and rotate in their
sockets.
The described connection is only suitable for such couplings for complete revolution.
in which the path described by the point C¹ is an ellipse. If the path is a hyperbola,
or a parabola, the said connection only allows of partial rotation.
The couplings represented diagrammatically in Figures 1, 5, 7, 8, 10, 11 and 12
could consequently be readily carried out according to the construction Fig. 13 for
complete revolutions, while with the other Figures the described construction is suited
for partial revolutions, or reciprocating motion.
For practical application of the construction the mechanism can be modified in order
to enable it to transmit considerable power. In the first place, it is evident that the
pivot o at CFig. 13 can be dispensed with if it is otherwise arranged that the arms a
and shall always move in accordance with the above stated law.
If both shafts A A and B B' are so placed that the geometrical axes of the arms a
and b always intersect at the point C, it will evidently be sufficient if only the pressing
surfaces of the rotating couple at C be carried out. The sliding motion of the
arms a bin their sockets a' ' can also be dispensed with if at the same time the
pressing surfaces are so formed that the surfaces of the arins a and b which are in
contact can shift relatively to each other without interfering with their rotation in
their sockets.
In order that this may be possible, the geometrical axes of rotation of the arms a b
must lie in the said contact surfaces. Fig. 14 shews such a construction of coupling,
which corresponds to the diagram at Fig. 5. In the crank shaped sockets a¹¹ of the
shafts A A and B B are mounted the arms a and b which have formed on their pro-
jecting ends the flat surfaces a² 62, by means of which the arms a bare continuously
in contact. The arms a bare rotatable in the sockets a¹ and are secured therein, by
way of example, by means of screws taking into circular grooves in the arms a b.
This coupling is only suited for rotation in one direction; it will be shown later on
however, how it can be made suitable for rotating in both directions.
The above described arrangement in which the pivotal connection of the arms a b
is dispensed with can be applied to couplings in which the point C describes a hyper-
bola, parabola, or straight line for transmitting complete revolutions, if several pairs
of transmitting arms are provided, which consequently maintain the connection
between the shafts.
For practical application, such constructions of couplings of the described kind
are suited in which the two arms a do not perform complete revolutions in their
sockets ab, as in that case the rotating couple constituted by the arms a band a¹ b
need not be completely formed. In this case both the arms and the sockets need
only be partially constructed, but at the same time the sockets a should be
extended so far as to extend beyond the point C. The sockets require in that case to
he so formed as to allow of the necessary free movement of the arms a b. Fig. 15
shews such a construction derived from the coupling at Fig. 13, only the one socket a
being drawn in full lines while the other one is shewn dotted. Both arms a b have
the form of semi cylinders which can turn and slide longitudinally to the required
extent in the correspondingly formed cavities of the sockets a¹. These semi

page_text: cylinders are in addition connected together by the pivot o placed perpendicularly to
the surfaces a² b³.
If the pivot o be omitted the recesses of the sockets are made equal in length
to the semi cylinders a b so that these are prevented from shifting longitudinally, in
the same way as the arms a bare held by the screw i and circular grooves at Fig. 14.
Fig. 16 shews such an arrangement, in which the socket is again shewn in dotted
lines. In this construction the connection of the two arms consists simply of two
cylinder sections which are either of equal size as at Fig. 17, or unequal as at
Figs. 18 to 20.
If the plane of intersection does not coincide with the axis of the cylinders, as at
Figs. 18 and 19, the transmission will only he approximately correct, but can still be
practically used. Such a coupling joint can he termed a sectional joint," but this
term may also be applied to the joints shewn at Figs. 14 and 15.
As the balf joints have only to turn in their sockets and the longitudinal shifting
is limited to the plane surfaces a² 6, these joints can also be formed of conic sections
or sections of other bodies of revolution; and it is also possible to form each
member of a pair according to a different body of revolution, such as the one
member of a cylindrical section, and the other of a conic section. In this case also
the edges of the sockets a¹ have to be sloped off as at Fig. 21, so that these paris
may perform the requisite angular movement relative to each other without touching.
Instead of preventing the longitudinal shifting of the sections of bodies of
rotation ab, by fitting with their end surfaces against the end surfaces of the
sockets a, this may be effected by a suitable formation of the surfaces of revolution
and their sockets, or by forming projections and recesses thereon.
Fig. 22 shews by way of example such a construction of the parts. The body a
in this case is formed with lips a fitting over projections a' on the socket a¹.
Further modifications may be obtained from the construction indicated at. Fig. 15
if instead of connecting a and b by a pivot o, the one part be formed with a
projection Fig. 23, fitting into a corresponding recess in the other part, such
projection and recess being so formed as to allow of the two parts turning upon one
another. In this case the plane sectional surfaces can be replaced by surfaces of
bodies of revolution whose common axis coincides with that of the projection and
recess, and passes through the point of intersection of the geometrical axes of the
transmitting arms in a direction at right angles to these axes.
Lastly if the parts ab Fig. 15 be omitted, the pivot o will be guided directly in
the recesses of the sockets a 1, in which case its ends will have to be made spherical
to correspond with the form of the recesses.
The simplest form will therefore be a sphere which can run in the recesses or
grooves of the two sockets a Fig. 24. Such a joint might be termed a "spherical
joint."
The constructions shewn at Figs. 15 16 17 and 23 can also be applied to two arins
acting upon each other, by, for instance, applying the arrangement shewn at Fig. 15
for the driving arm, while the driven arm is constructed according to Fig. 16 with a
semi cylinder which can turn but not shift longitudinally in its socket.
The circular recess required in Figs. 15 and 23 for the pivot of the other semi
cylinder to work in, must in this case be converted into a longitudinal slot as
at Fig. 33.
With all the described connections and joints the lines A' C' and B'C' indicated
in the diagrams Figs. 1 to 12 as transmitting arms, appear as axes of rotation round
which either the arms a brevolve in their sockets a Fig. 13, or the elements a b
of the joints Figs. 14 to 23, or the spheres of the joint Fig. 24 turn.
These geometrical axes have therefore to be arranged in a perfectly definite
manner, corresponding to the laws above set forth, without requiring to take the
configuration of the bodies of rotation and their sockets into consideration.
If a pivot o is employed for the connection of the two arms ab Fig. 14 or the
half joints ab Fig. 15, the geometrical axis of rotation must pass through the points
of intersection of those two geometrical axes as only in that case can the shifting

page_text: of the transmitting arms A' C and B₁ C relatively to each other, as described with
reference to Figs. 1 to 12, take place.
Figs. 34 and 35 shew crossing axes in which knife edges are arranged in place of
the bodies of rotation. The apices of the knife edges correspond accurately to the
geometrical axes of the transmitting arms and consequently follow the same laws of
motion, but they are only applicable for transmitting small powers, and consequently
serve rather to transmit motion than force.
The construction of a coupling by means of the sectional joint only requires one
further device by means of which the joint surfaces or the sockets a¹are prevented
from moving apart; this can be effected by the application of counter sectional
joints. Such an arrangement is shewn at Fig. 25, which shews the one of two
similar coupling halves.
The sectional joints C₁ and Care assumed to be driving; opposed to these are
the joints C, and C, which insure the continuous contact of the joints C¹ and C³.
Fig. 26 shews another example. Here each of the half couplings has three arms;
Cand Care the driving joints, C₁, is a counter joint, operating both against C2
and C. Fig. 27 shews another arrangement in which the counter joints C¹ and C¹,
lie in the same plane as the diametrically opposite driving joints C, and C. The
If a coupling
same arrangement can also be applied to the spherical joint Fig. 24.
is to be altered to suit an angle of the shafts different from that first adopted, the
fundamental conditions as above stated with reference to Fig. must be observed, as
otherwise the several arms of a coupling would tend to drive at different speeds,
resulting in a locking or fracture.
The displacement of the bearings of the shaft B B Fig. 28 for altering the
angular position of the shafts, could therefore only be effected upon a geometrical
axis which has a point P in common with the symmetrical axis S C and which is
It is most convenient to
perpendicular to the plane of the angle of the shaft axes.
take the centre S' of the two axes as the point of intersection for the displacement.
A bearing for the shaft B B might be so arranged that rotation could be effected
round S or even round P with suitable change of position of the shaft.
It is however necessary to consider how to arrange matters when the shaft B is
connected at both ends, by a jointed coupling, to another shaft, as at Fig. 30, and
when it is required that the shaft D shall be capable of shifting relatively to the
shaft A.
In this case the new coupling affords a farther advantageous property, which is of
great value for its application. If in the arrangement at Fig. 25 it be observed that,
in the cross section of the coupling in particular that through the symmetrical plane,
there are four supporting points 0 0 C, which prevent all transverse motion of
the one half coupling relatively to the other, and if at the same time it be considered
that the longitudinal motion thereof relatively to each other is not prevented
thereby, it will be observed that the half couplings can, for example be drawn apart
as at Fig. 29, thereby giving them a new point of intersection S' instead of S,
whereupon every shifting of B will produce à rotation thereof round this new point
of intersection, therefore always round a point in the symmetrical axis. This does
It will
away with the necessity of giving a special bearing to the middle shaft B.
generally be of advantage, to connect it at one of the two points of intersection
for example at S. Fig. 30 by a ball and socket or eqivalent joint to the next axis,
at S however, assuming that the sectional joint surfaces are made long enough, no
special bearing will be necessary the perfect uniformity of the transmission of rotation
with any displacement of D relatively to A being nevertheless insured.
In the case where the support in the symmetrical plane is not afforded in four
directions, as at Figs. 26 and 27, the separate supporting of the shaft B B cannot be
dispensed with.
In the foregoing descriptions the construction of the coupling has been given
more or less diagrammatically; Figs. 31 and 32 shew a practical construction of the
coupling according to Fig. 25. In this case the angles of the four transmitting
armis employed are made equal. Also, the distance of the points A¹ and A Fig. 11

page_text: from the point. S are equal. The geometrical axes of each pair lie in one and the
same plane, and the two planes thus determined stand perpendicular to each other.
In both Figures the half coupling A is drawn full, the half B in section. As shewn
inore particularly at Fig. 32, the two halves A and B gear together in a similar
manner to a claw coupling, and between the several surfaces are arranged four
sectional joints a, b, of the kind shewn in Figs. 16 or 17.
Having now particularly described and ascertained the nature of this inven-
Lion and in what manner the same is to be performed I declare that what I
claim is :-
1. A jointed coupling for shafts adapted for transmitting uniform rotary motion
when the shafts are at an angle to each other, wherein each half coupling carries
one or more transmitting arms or equivalent parts A¹ C and B' (so arranged that
each arm of the one half coupling intersects or gears with the corresponding arm of
the other half coupling at a point (which, during rotation, describes a path situated
in a plane passing through the point of intersection of the axes of the two shafts
and symmetrically situated in respect of these, substantially as herein described.
2. In a coupling constructed as set forth in the preceding claim, the combination
of two arms a b pivotted together at o and arranged to both slide and revolve in
sockets a b¹ fixed to the shafts A B, substantially as herein described with reference
to Fig. 13.
3. In a coupling constructed as set forth in the first claim, the combination of two
arms a, b, carried in sockets a fixed to the shafts A B, the said arms being formed
as the sections of bodies of revolution capable of turning or of both turning and
shifting longitudinally in their sockets, and gearing together with their plane
sectional surfaces, substantially as described with reference to Figs. 14 to 23, 31
and 32.
4. In the construction of coupling referred to in the first claim, the combination
of two arms consisting of sockets a fixed to the shafts A B, and of a sphere or
pivot with spherical ends fitting in correspondingly formed recossos or grooves in
both sockets, in which the sphere or pivot is free to slide longitudinally substantially
as described with reference to Fig. 24.
Dated this 12th day of August 1880
ABEL & IMRAY,
Agents for the Applicant.