A COMBINED FRICTION AND CLUTCH COUPLING
Year: 1884

page_text: We MAX LOHMANN of Hannover Prussia German Empire and MAX STOLTERFONT
of Berlin Prussia German Empire do hereby declare the nature of the said invention
for "A COMBINED FRICTION AND CLUTCH COUPLING" to be as follows :—
In friction couplings as heretofore constructed engagement of the parts is
produced by gradually increasing pressure between the parts of the coupling;
during some part of the "shipping" of such gear power is used up although the
"loose" part does not run with the "fixed" part. This produces heat and is
disadvantageous.
The present invention is designed to obviate this difficulty by constantly pressing
the friction surfaces against one another with an adjustable even pressure whether
the coupling is operative or not and for throwing into or out of gear combining
them with a clutch coupling so that the time during which the friction surfaces
slip upon one another is limited to a minimum.
The improved coupling is capable of several modifications. In all forms one of
the parts (either the driving or the driven part) is fitted with clutch teeth and
there is an intermediary device pressing with constant adjustable elastic pressure
against the one part and having clutch-teeth corresponding with the other part.
This invention may be applied say for connecting a wheel and pulley intermittently
and may be constructed as follows.
The pulley is not fixed directly upon the shaft but upon a sleeve and the pulley
boss encloses said sleeve with an adjustable elastic pressure. In this instance the
friction surfaces are cylindrical. The sleeve is at one end provided with clutch
teeth capable of gearing into those of another sleeve carried by the shaft. By
shifting the pulley with its sleeve the pulley and shaft may be coupled.
Two shafts may be connected as follows: upon one of the shafts is fixed a disc
with plane friction surface, against which another disc is pressed by springs.
The second disc has the clutch teeth for gearing with the sleeve fixed on the
corresponding shaft.
The invention is capable of further modification and conical friction surfaces will
in some cases be advantageous.
The shock of the clutch when thrown into gear is equalized by a slight slip of
the friction surfaces and the clutch part will therefore be made small and may
consist of single clutch teeth and with this conical cylindrical and straight friction
surfaces in combination may be used the teeth taking into corresponding notches
or indentations on the boss of a wheel.
j

page_text: The improved clutch may be applied to existing pulleys by providing the teeth
on the part already existing and the friction part with the intermediary device on
the shaft.
The pressure between the frictional parts may be produced by any convenient
means and spring steel leather India rubber or paper may be employed, or the
parts may themselves be so formed as to be elastic.
The form of the clutch teeth may also be varied and the clutch part be rendered
elastic; for instanco the clutch teeth may have helical springs surrounding the
shaft viz the ends of two stout coiled springs may form teeth for the clutch or the
teeth may be placed at a suitable angle and have the form of hollow cones so that
they may be coupled in either direction or movable claws say in the form of levers
moving on a fulcrum may be employed, in the coupling.
To ascertain whether or not an excessive slip takes place in the coupling,
a signalling device may be employed; a bell or a sounding spring may be placed on
one of the friction parts one or more pins being provided on the other which cause
the bell or spring to sound when the two parts slip upon one another. The
number of strokes indicates whether the clutch is working properly or whether it
requires to be lubricated or otherwise to be attended to.

page_text: We MAX LOHMANN, Hanover Prussia, German empire and MAX STOLTERFOHT,
Berlin, Prussia, Germany, do hereby declare the nature of this invention for
"A COMBINED FRICTION AND CLUTCH COUPLING" and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement:―
In friction couplings as heretofore constructed engagement or disengagement of
the parts is produced by gradually increasing or decreasing the pressure between
the parts of the coupling; during some part of the "shipping" of such gear power
is used up although the "loose" part does not run with the "fixed" part. This
produces heat and is disadvantageous.
The present invention is designed to obviate this difficulty by constantly pressing
the friction surfaces against one another with an adjustable even pressure whether
the coupling is operative or not and for throwing into or out of gear combining
them with a clutch coupling so that the time during which the friction surfaces slip
upon one another is limited to a minimum.
The improved coupling is capable of several modifications. In all forms one of
the parts (either the driving or the driven part) is fitted with clutch teeth and
there is an intermediary device pressing with constant adjustable, elastic pressure
against the one part and having clutch teeth corresponding with the other part.
This invention may be applied say for connecting a wheel and pulloy inter-
mittently and the construction may be as follows.
The pulley is not fixed directly upon the shaft but upon a sleeve and the pulley
boss, encloses said sleeve with an adjustable elastic pressure. In thisi nstance the
friction surfaces are cylindrical. The sleeve is at one end provided with clutch teeth
capable of gearing into those of another sleeve carried by the shaft. By shifting
the pulley with its sleeve the pulley and shaft may be coupled.
Two shafts may be connected as follows. Upon one of the shafts is fixed a disc
with plane friction surfaces against which another disc is pressed by springs.
The second disc has the clutch teeth for gearing with the sleeve fixed on the
corresponding shaft.
The invention is capable of further modification and conical friction surfaces will
in some cases be advantageous.
The shock of the clutch when thrown into gear is equalized by a slight slip of
the friction surfaces and the clutch part will therefore be made small and may
consist of single clutch teeth and with this conical cylindrical and straight friction
surfaces in combination may be used the toeth taking into corresponding notches or
indentations on the boss of a wheel.
The improved clutch may be applied to existing pulleys by providing the teeth
on the part already existing and the friction part with the intermediary device on
the shaft.
The pressure between the frictional parts may be produced by any convenient
means and spring, steel, leather India rubber or paper may be employed, or the
parts may themselves, be so formed as to be elastic.

page_text: The form of the clutch teeth may also be varied and the clutch part be rendered
elastic, for instance the clutch teeth may form helical springs surrounding the
shaft namely the ends of two stout coiled springs may form teeth for the clutch or
the teeth may be placed at a suitable angle and have the form of hollow cones so
that they may be coupled in either direction or inovable claws say in the form of 5
levers moving on a fulcrum may be employed in the coupling.
To ascertain whether or not an excessive slip takes place in the coupling, a
signalling device may be employed a bell or a sounding spring inay be placed on one
of the friction parts one or more pins being provided on the other which cause the.
bell or spring to sound when the two parts slip upon one another. The number of 1
strokes indicates whether the clutch is working properly or whether it requires to
be lubricated or otherwise to be attended to.
In the annexed drawings various examples of clutches embodying this invention
have been represented. In all the figures a a is the part of machinery (whether
driving or driven) which is provided with friction surfaces b the part of machinery 1
whether driving or driven having claws or teeth, c is a piece serving as a connection
between the first mentioned two parts and it has on one side friction surfacos
pressing with a constant, adjustable elastic pressure against the friction surfaces
of a and moreover teeth or claws to engage with those on b and capable of being
disengaged therefrom.
In figure 1 the application of this coupling to a pulley which has from time to
time to be connected with a shaft is shown as one example.
The pulley a is not mounted directly upon the shaft "A" but upon a sleeve c
and its hub encloses the said sleeve c with a pressure that can be varied by the
spring d-Here the frictional surfaces are cylindrical-The sleeve c is at one end
fitted with clutch teeth which are capable of engaging with the clutch teeth of the
sleeve b. This sleeve is moved together with the shaft "A" and it is clear that
the coupling or engagement may be effected by shifting the pulleys by means of
the sleeve c against sleeve b.
In figure 2 is represented the coupling of two parallel shafts. On one of the
shafts is fixed a disc a having plane friction surfaces against which the disc c is
pressed by adjustable springs & here again the parts c has clutch teeth being capable
of being thrown into or out of gear with the sleeve b.
Even from these two examples it will become apparent that the form of the
friction surfaces can be greatly varied in rotary parts of machinery rotating surfaces
will however always be selected and besides those above illustrated conical faces
will be advantageously employed.
In starting the concussion of the inasses which are brought together is equalized
by a slight amount of slip between the friction surfaces and it is clear that the loss
occurring at the concussion will be the smaller, the smaller the mass of the
intervening piece c is. This piece c should therefore be made as small as possiblo
without however reducing the friction surfaces to the proportions required for safe
lubrication.
The construction shown in Figure 3 may be taken as representing the limit in
this direction. Here conical cylindrical and flat surfaces are employed and the
part c consists of separate clutch teeth which are suitably spaced and pressed upon
by springs d in a circular groove of the wheel a-In this construction therefore
3 surfaces of each of the bodies cure used as friction surfaces.
Figure 4 shows how this improved claw-friction coupling can be readily applied
to existing pulleys--Here the existing part of machinery 6 is furnished with claws
and the parts a and c are provided on the shaft A. It is obvious that the arrange-
ment and construction of the springs & serving for the production of the friction
between the friction surfaces may be of any suitable construction and arrangement
and may be not only steel but also other elastic material such as leather, rubber or
paper, or one or the other of the parts a and c may be made springy; the con-
struction and shape of tho claw-teeth may also vary as desired,

page_text: In the modifications of the coupling shown in Figures 5 to 8 the claw piece c is
pressed with a strongly elastic axial pressure capable of being easily regulated
either between a conical surface a and a plane surface b, figures 5 and 8 or between
a conical surface a and a cylindrical surface b figure 6, or between two conical
surfaces a and b figure 7.
In all these forms the claw piece c is outwardly confined by a conical friction
surface a which is intended to transmit the main portion of the power.
The second surface, conical or plane which lies nearer the axis of rotation is
intended merely to transmit the elastic axial pressure upon the main friction surface.
Figure 9 shows a longitudinal section and elevation of a friction cone made in
one piece with the friction cone c. In this construction the claw teeth are about
twice as long as the part which comes into engagement and from there to their
roots the teeth gradually become larger as is particularly shown in the detail view
of two teeth also forming part of figure 9. Both these circumstances increase their
capacity to resist shocks.
In figure 10 teeth for pawls are shown instead of the teeth for claws; they are
arranged upon a collar on the shaft, the elasticity of which collar ŕ likewise
increases the capacity of the coupling to resist shocks or concussions.
The form of claw teeth represented in Figure 11 allows the coupling to be
thrown into gear during rapid rotation in either direction and when fully thrown
into gear the power will be transmitted in either direction.
The signal boll S on one part of the coupling is sounded by one or more studs
on the other but the studs do not actuate the bell when the clutch is out of gear.
If however the two coupling pieces are brought near one another to such extent
that their teeth nearly touch the pin or pins S₁ and strike the bell S when the
parts are in that position in which the clutch-teeth can be safely slipped into full
engagement.
Figure 12 shows how the same object may be attained by mounting pawls on
one part of the clutch and corresponding teeth on the other.
In Figures 13 and 14 are specially shown two constructions of clutch teeth which
have for their object to form the whole clutch as an elastic body.
The clutch teeth figure 13 have the form of helical springs wound round the
shaft A, whilst in Figure 14 those surfaces of the teeth which impinge upon one
another form an angle of about 30° to 5° with the direction of the rotary movement
whereby one part of the work required for accelerating the motion of the mass or
body of the claws is transformed into heat whilst another part is taken up by the
elasticity of the material in that part of machinery the fibres of which are at even
tension (or nearly so) throughout.
The clutch teeth of the part 6 are here so arranged as hollow conical toothed
gearing that c and b can be coupled in both directions of motion.
This coupling may be used for rotating as well as for reciprocating parts of
machinery.
Figure 15 indicates as an example the coupling of the rod a with the recipro-
cating body b the movable claws or pawls whereof engage the body c mounted on a
with variable frictional pressure.
In these couplings it is essential the pressure between the friction surfaces bo
such as to reduce the slip to a minimum.
To be able to ascertain readily whether injurious slip takes place we connect
with this coupling a signal device which becomes operative when the surfaces slip
on one another. To this end a bell m or a sounding spring may be fixed upon a
whilst upon c one or more pins n are so fixed that they will cause the bell or spring
to sound when the parts a and c slip one upon the other.
The number of strokes indicates whether the coupling is in good order, whether
it requires lubrication, whether the resistances during working exceed the allowable
limits, how often, for how long and to what extent the coupling becomes heated
and whether working can be continued without fear of heating or whether the
work should be stopped, all of which will be ascertained by practice.

page_text: These couplings are applicable to driven as well as to driving parts of machinery
such as pulleys toothed wheels, rope, sheaves and the like.
Having now particularly described and ascertained the nature of tho said
invention and in what manner the same is to be performed I declare that what
I claim is
1. The method of fitting the one toothed portion of the coupling with friction
surfaces to which correspond friction surfaces on the driving or driven part of
machinery on which said part is mounted, the pressure with which the friction
surfaces bear against one another being capable of regulation substantially as set
forth.
2. A claw-friction-coupling consisting of a part or piece a connected with a
driving or a driven part of machinery and provided with friction surfaces a part b
connected with either the driven or the driving part of the machinery provided
with clutch teeth and a part or piece c having friction surfaces corresponding with
those of a (against which they are pressed with a variable pressure) and clutch
teeth capable of engaging with those of the whole constructed and operating
substantially as specified.
3. In the herein described friction coupling the insertion of the friction cone of
the clutch-piece c between a conical fiction surface a serving to transmit the
main portion of the force and a plane surface 6 (figures 5 and 8) or a conical
surface a and a cylindrical surface b (figure 6) or between two conical surfaces c
and b figure 7 substantially as set forth.
4. In claw-friction couplings the construction of the friction cone as shown in
figures 9 and 10 with the clutch-teeth or pawl-teeth so made in one piece as to
provide great resistance against shocks.
5. In claw friction couplings the form of clutch-teeth or pawl-teeth as illustrated
by figures 11 and 12 so as to allow rigid connection in either direction of motion.
6. The employment, of pawls instead of clutch teeth in combined friction and
clutch couplings and the construction of such pawls in one pieco with their axles.
7. The clutch teeth formed by springs coiled in helices round the shaft substan-
tially-as set forth and shown in figure 13.
8. In claw-friction couplings the employment of clutch teeth the meeting faces
whereof form an angle of from 30° to 5° with the direction of motion seo
figure 14.
9. The method of ascertaining the slipping of the friction surfaces upon one
another in combined friction and clutch couplings by means of an acoustic signalling
device.
"