Improvements in Friction Couplings.
Year: 1893

page_text: Date of Application, 24th Feb., 1893
Complete Specification Left, 16th Nov., 1893-Accepted, 30th Dec., 1893
PROVISIONAL SPECIFICATION.
Improvements in Friction Couplings.
We, JOSEPH VILLARD and JEAN HENRI CHARLES WITTMANN, of 62 Rue de
Provence Paris, in the Republic of France Engineers do hereby declare the nature
of this invention to be as follows:-
This invention for improvements in friction couplings relates to apparatus for
transmitting motion from one rotating shaft or other piece to another; and consists
essentially of means or mechanism for controlling the friction between the periphery
of a pulley or its equivalent connected with one rotating piece and an encircling
band connected to the other.
In one form of friction coupling apparatus, constructed according to this
invention, for transmitting rotary motion from a rotating shaft to a pulley loosely
mounted thereon: a crank or lever rigidly mounted on one end of a spindle
working in bearings in the pulley is differentially connected to the two free ends of
a friction band encircling the periphery of a friction pulley or disc keyed, or
otherwise secured, to the driving shaft.
Mounted loosely on the boss of the driven pulley, or on the driving shaft, is a
grooved controlling pulley having a lug carrying a pin which engages in a slot in a
lever mounted on the aforesaid spindle of the friction band lever, so that the
rotation of the said grooved pulley relatively to the loose transmitting pulley causes
the friction band to be either tightened or slackened on its enclosed friction pulley.
Normally the friction band is held tightly pressed against the friction pulley by
means of a spring on the driven pulley which is connected to the grooved controlling
pulley.
Around the grooved controlling pulley wound one or more convolutions of a
cord or tape, one end of which is connected to a spring depending from any fixed
support extraneous to the driving apparatus, the other end hanging vertically and
free and being secured to a suitable handle.
In the normal or engaged position of the apparatus the driving friction pulley or
disc is gripped by its encircling band, the controlling mechanism being held in this
position by the beforementioned spring connected to the sector of the grooved
controlling pulley, but on pulling the end of the suspended controlling cord it grips
the said pulley and acts as a brake and reverses the action of the controlling
mechanism against the force of the retaining spring, and thereby removes the
pressure between the friction band and pulley. An air or liquid brake, or dash pot
or the like is connected to the controlling mechanism and prevents shocks by
causing the engagement to be effected gradually.
It will be obvious that the operation described above may be reversed, the loose
pulley forming the driving part; or the apparatus may be used to connect two
shafts running in alignment with one another, the friction pulley being on one shaft
and the friction band controlling mechanism on the other; and that the controlling
apparatus can be readily operated from a distance, either by mechanical or
electrical means.
In a modification of the hereinbefore described apparatus the grooved controlling
pulley is dispensed with, and the controlling mechanism is composed entirely of
rigid parts and linkwork put into and out of operation by means of a sliding sleeve
operated by a hand lever."
Or the grooved controlling pulley hereinbefore described is replaced by a sliding
sleeve to which is secured a coarse pitched screw passing through a pinion gearing

page_text: with a sector secured to the friction band lever spindle so that as its sleeve is
slidden axially in either direction the said pinion is rotated and the friction band
operated.
Dated this 24th day of February 1893.
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.
Improvements in Friction Couplings.
We JOSEPH VILLARD and JEAN HENRI CHARLES WITTMANN, of 62 Rue
de, Provence, 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 :-
This invention for improvements in friction couplings relates to apparatus for
transmitting motion from one rotating shaft or other piece to another and consists
essentially of means or mechanism for controlling the friction between the
periphery of a pulley or its equivalent connected with one rotating piece and an
encircling band connected to the other.
Our invention may be applied to all cases of coupling, thus for example the
shaft may be the motor and transmit its force to the loose pulley which is to be
coupled or the pulley may be the motive power and transmit its force to the shaft
which has to be coupled but in either case and in all others the principle of the
apparatus is the same, and in the annexed drawings which represent our invention
we describe the case of a shaft commanding a loose pulley.
In these drawings the same letters indicate the same parts.
Fig. 1 is an exterior view of our coupler.
Fig. 2. is a transverse section on X-Y of Fig. 1 (left part sectioned).
Figs. 3 and 4 represent two modifications of the movement shown by Figs.
and 2. A pulley A is mounted loosely on the driving shaft N and carries a small
crank B oscillating on the pivot a. On the crank B are jointed the two end pins b
and c of a hoop or band e running round the friction pulley C keyed on the driving
shaft N. At the end of the shaft a is fixed a controlling lever D provided with
a slot.
A small grooved pulley E mounted loosely on the boss of the pulley A (or
loosely on the shaft N if preferred) carries on one side a projecting part with a
pin d engaging in the slot of the lever D and on the other side a grooved sector e¹
on which runs a metallic cord f attached at one end to a stop g on the sector
and at
the other end to a small barrel F fixed on one of the arms of the loose pulley A,
this small barrel contains a spiral spring which gives a certain tension to the
cord f. A cord or tape running round the groove on the pulley E is attached
at one end to a spring H fixed independently of the apparatus and at the other
end carries a handle j for its operation.
The following is the action of the apparatus. The apparatus not being in
couple the tension on the cord his maintained by fixing it by means of the handle j
to any suitable stop k and the apparatus remains in the same state of disengage-
ment, due to the pull on the cord / and to the resulting friction on the neck of the
pulley E.
To effect the engagement it is sufficient to unhook and leave free the cord /
when the friction on the pulley E ceasing, the barrel F pulls on the cord the
pulley E turns on its axis and operates through the pin d, the lever D, the
spindle a and the crank B.
The two end pins b and c both move towards the left, the first tends to open the
band or hoop e and the second to tighten it on the friction crown C.
The first pin 6 travels a less distance than the second, and from this difference

page_text: results the covering and a commencement of tightening of the band e on the
crown C.
If the shaft which carries the crown C is in movement the friction of this
crown on the band produces, due to this difference in the lengths of travel, a
tightening of the latter more or less energetic. This tightening effects the
connection of the pulley A with the crown C the first then participating in the
movement of the second.
To disengage during rotation it is sufficient to pull lightly the lower end of the
cord in order to produce a sufficient frictional force on the pulley E, the move-
ment of this pulley is then retarded, it carries with it the lever D which takes up
the position of disengagement; the band is then open and the crown turns freely
within it.
Stops provided, if necessary, with regulating screws, are fitted on the pulley in
order to regulate the opening of the band and to prevent it falling on the
crown C.
It is advisable for large forces and especially for high speeds that all the parts
connected to the crank B and the latter itself should be in equilibrium. These are
the parts BDE and the pins b and c. The loose pulley A should also be equalised
by a counterweight M.
The spring H has for its object to maintain the tension on the cord the whole
time the apparatus should remain disengaged.
An air brake K consisting of air cylinder, a piston, the rod, and a link connected
to the actuating lever D has for its object to control the rapidity of the engage-
ment to effect a softer movement and avoid shocks. The exit of the air from the
cylinder is effected by any suitable orifice. The air may be replaced by a liquid
the flow of which may be regulated by a small orifice between two chambers in the
cylinder. This brake may be replaced by a simple friction brake the piston then
carrying an india rubber ring, the friction of which against the surface of the
cylinder is regulated as desired by pressing the said ring more or less strongly
between the piston and another plate.
We have only represented the case of the engagement indicated above, but our
coupling is equally applicable, without modifying anything in the band, its
suspension, or the operation thereof, to the case of a loose pulley actuating a shaft
and to that of two shafts on which one is a prolongation of the other. We will
point out here that the characteristic of our apparatus consists of a band of which
the two extremities and c are jointed to one oscillating piece B as shown in
Figs. 1 and 2.
In these two figures the band e is represented exterior to the friction pulley but
it may also be inside and work according to the saine principles. The band may
be lined with leather n, wood, paper &c. or be a plain metal band or even a simple
cord or cable, it may also be of a trapezoidal shape and engage in a pulley with an
angular groove. The crank B may be reversed and the suspension axis a may be
placed below the joints of the end pins and c.
The band which has been indicated as to be mounted on the part to be engaged
or set in motion may also be mounted on the engaging or motive portion without
interfering with the good working of the apparatus.
The small power required to engage or disengage our coupling allows of its
control from a distance either electrically or by means of a simple cord.
The controlling movement represented by Fig. 3 is a modification of that shown
in Figs. 1 and 2. This movement is composed entirely of rigid parts and dispenses
with the use of the barrel F and the brake k. The tightening of the band or belt e
and the graduation of the engagement depend upon the operator who controls the
lever. In this figure D is a lever mounted on the axis a, S is a grooved sleeve
sliding on the boss of the pulley a. o is a sliding rod carrying a bolt which
engages in the groove of the lever D. P are the guides of the rod o fixed on the
arms of the pulley A.
Qis a small oblique connecting link jointed at one end to the sliding sleeve S

page_text: and at the other end to the rod o. R is a fork hand lever engaging in the groove
of the sleeve S. This operating lever R is fixed in the position of engagement or
disengagement by means of a stop.
The controlling movement represented on Fig. 4 is a second modification of the
movement represented by Figs. 1 and 2.
E is a small sleeve sliding on a key fixed on the boss of the pulley a. V is a
screw with a very steep pitch, fixed to the sleeve E. G is a small toothed wheel
which can rotate in a boss in the pulley A; its boss forms a nut for the screw V.
I is a toothed sector engaging in the pinion G. J is a half collar for actuating
the sleeve E. T is the operating lever, L the fixed point of the lever. By
pushing the sleeve forward or backward the screw V is inserted or withdrawn from
the toothed wheel G. This movement produces the rotation of the wheel G
which in its turn operates the sector I attached to the suspension axis of the band
or belt.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. In transmission clutches a band e the two extremities of which are. jointed at
the two points a and b to the same oscillating piece B thus allowing the automatic
tightening of the band on the crown c and this tightening being in itself pro-
portionate to the force transmitted, as described and illustrated.
2. The general arrangement and combination of parts substantially as described
in the foregoing Specification and shown on the annexed drawings.
Dated this 16th day of November 1893.
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.