Improvements in or relating to Clutches or Engaging Devices for Driving Mechanism and similar purposes.
Year: 1897

page_text: Date of Application, 13th Feb., 1897-Accepted, 17th Apr., 1397
COMPLETE SPECIFICATION.
Improvements in or relating to Clutches or Engaging Devices for
Driving Mechanism and similar purposes.
We, JOSEPH VILLARD, and JULES BONNAFFOUS, of 207 Boulevard Voltaire, Paris in
the Republic of France Engineers, 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 :-
The coupling forming the subject of the present invention is characterised chiefly
by the arrangement of a band in such a manner as to cause the engaging action or
the friction of the band always to take place progressively from one end of the band
to the other whatever be the direction in which the parts rotate.
In the accompanying drawings,
Fig. 1 is an elevation and Fig. 2 a section of one form of the invention.
Fig. 3 shows a modification in which the band is divided into two independently
operated parts.
Fig. 4 shows a modification for coupling together two motors.
In Figs. 1 and 2, A is a friction cup secured to the shaft X and provided with
openings bb for the discharge or introduction of lubricating material. Within the
cup A rotates a disc or part B carrying the coupling or friction band C and secured
on the driving shaft Y on which slides a grooved sleeve I on a feather key or
equivalent device. The band support B has preferably a circular rim S and a bracket
or projection to which are hinged the ends of the steel-band C (which presses:
against the rim S when the coupling is in operation) leaving a uniform and sufficient
space between the inner wall of the cup A and the band which may be covered if
desired with a layer D of leather wood vulcanised fibre or any other material adapted:
to produce friction. The ends of the band are provided with lugs E hinged to links E
one of which is hinged to the bracket at F and the other to a movable part at F2 such
part being conveniently in the form of a bell-crank lever H. pivotted on the bracket at
the point F¹.
It will be evident that when the lever H is raised it will push outwards or forwards
the end of the band attached at F2 so that the diameter of the band is increased
throughout its length (the distance between the ends being somewhat increased) and
the band will be pressed outwards in a uniform manner more or less strongly against
the inner wall of the cup A the engagement between said cup and the disc B being
thus produced and the direction of friction being such that the band has a tendency
to expand. It will also be seen that disengagement may be instantaneously effected
by lowering the lever H whereby the band will be contracted and again drawn round
the rim S. Owing to the provision of intermediate links E¹ the band can be expanded
and applied in a very satisfactory manner against the cup even if the shaft Y be
considerably out of line relatively to the shaft X.
The bell crank lever H is operated by moving the grooved sleeve I in one or the other
direction as these two parts are connected by an adjustable connection J having ball-
and-socket joints on each end formed in screwed nuts L and N which secure the balls
in their spherical hollow spaces one ball being on the regulating screwed rod K and
the other on a pin M fixed on the end of an arm i of the sleeve I which rests by means
of a roller m on a guide n formed in the band support B and forming an abutment
for the part J when the coupling is brought into operation.
To do this it is only necessary to push the sleeve I towards the band support B

page_text: whereupon the rod J will take up an upright position (when viewed as in Fig. 2) and
raise the lever H as described and when the foot m of said rod has passed a little
beyond the central plane of the band-support the apparatus will be automatically
maintained in position. The firmness with which the engaging halves maintain their
grip can be regulated by lengthening or shortening the adjustable rod by means of
the screw K and the apparatus may in this way be utilised to limit the power
transmitted that is to say the apparatus will slip when the load exceeds a given
maximum.
If the direction of rotation is reversed the grip becomes much smaller owing to the
flexibility of the lever H and slipping may then take place. This feature may be
utilised to deaden shocks caused by sudden changes of speed and of power for instance
in application to toothed gearing where it becomes particularly advantageous. If
the lever H were perfectly rigid the firmness of the grip would be the same whatever
be the direction of rotation.
In certain cases it is advisable to divide the band into two parts as shown in
Figure 3. There will then be two operating devices worked by two arins of the same
sleeve but it will be observed that nothing will be changed as regards the operation of
the halves of the band which always act on the same principle that is to say always in
the same direction. This arrangement effects a balance all the driving efforts and is
especially suitable for couplings in which the shaft of the band-support cannot
penetrate into the cup. In this modification as well as in the arrangement shown in
Figs. 1 and 2 intermediate links need not be used in which case the lugs on the bands
would be hinged directly at their points of attachment.
The modification shown in Fig. 4 is an arrangement for coupling together two
motors in which the two lugs E E on the band are hinged to two pivotted rods F F
connected by a link G. One of these rods F is the operating rod having a forked
end the power or extent of movement of the apparatus depending on the position of
the points O and 0" relatively to O on the arm F, H is a spring to balance the weight
of the parts of the mechanism. Figs. 5, 6 and 7 are details of the parts F F¹ and F
respectively.
The friction of the cup on the band moves the rods F F¹ to a certain extent. In
this movement the points 0' 0" move, their extent of movement being equal but
smaller than the movement of the point O of the rod F.
The travel of the ends and 0 of the rods F and F will therefore be unequal
consequently, the band will expand, if the cup is the driving part and rotates in the
direction indicated by the arrow.
This expansion will cease as soon as the friction becomes sufficiently great to equal
the driving force applied to the cup, when the parts will rotate together.
If the band support is the driving part, the movement of the rods will take place
in the opposite direction and complete disengagement will take place.
The proportion of the lengths of the lever arms 0 0' and 0 must be determined
in accordance with the size of the band and the coefficient of friction of the substance
of which the frictional surfaces are made.
Let us assume that X is the auxiliary motor connected to the cup and X¹ the main
motor connected to the band support. The two motors will work together and the
load will always be automatically distributed on each of them in proportion to their
power without noise or shocks.
If the motor X be stopped the motor X' will continue to turn without having any
connection with the former.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. A band coupling or engaging device in which the ends of the band are so
attached that the engaging action or friction takes place progressively from one end to
the other whatever be the direction of rotation of the coupling as hereinbefore
described.

page_text: 2. In a coupling or engaging device of the character described a disc supporting
the operating mechanism and having a circular rim and a bracket or projection for
attachment of the band and a band provided with lugs at each end for connecting said
band to the bracket and to a pivotted lever carried therein directly or by means of
intermediate links substantially as described.
3. In a coupling or engaging device of the character described the connection of a
sliding arm or extension of the rotating part guided by a roller on a guide of the band-
support with a bell crank lever actuating the band by means of an adjustable rod
having ball and socket connections substantially as described.
4. A modification of the coupling described consisting in the employment of two
bands actuated independently by two operating devices from the same sliding sleeve
substantially as described.
5. A modification of the coupling described for coupling together two motors
consisting of the employment of two pivotted rods connected together by an inter-
mediate link substantially as described and illustrated in Fig. 4 of the accompanying
drawings.
6. The combination and arrangement of parts forming the complete coupling or
engaging device substantially as described and illustrated in Figs. 1 and 2 of the
accompanying drawings.
BOULT & WADE,
Agents for the Applicants.