Improvements in Friction Clutches.
Year: 1888

page_text: Date of Application, 24th Oct.,. 1888
Complete Specification Left, 24th July, 1889-Accepted, 24th Aug., 1889
PROVISIONAL SPECIFICATION.
Improvements in Friction Clutches.
I, SAMUEL FORD, of 139 Hartington Road, South Lambeth, in the County of
Surrey, Engineer do hereby declare the nature of this invention to be as follows:-
This invention relates to that kind of friction clutch in which a revolving split
metallic friction ring contained within a cylindrical recess or box is pressed outwards
against the internal cylindrical walls of such recess or box by means of a wedge
pressed between the split ends of the said ring when it is desired to bring the clutch
into action and is drawn away from or out of contact with the internal cylindrical
wall of such recess or box by means of its own elasticity or otherwise when it is
desired to throw the clutch out of action.
In the friction clutches of this kind heretofore in use there have not been, so far
as I am aware, any efficient means for maintaining the friction ring concentric with
its containing recess or box when the clutch is thrown out of action, but that on the
contrary the said ring is liable at that time to come in contact, at some point or other
of its circumference with the interior of the said recess or box, and to rub against
the same as it revolves therein, thereby producing friction which causes the parts
of the clutch to become hot. To prevent this heating, lubrication is often applied
to the parts which come in contact, with the result that when the clutch is required
to be used its action is impaired by the presence of the lubricant between the frictional
surfaces. Similar effects are sometimes produced by the opening out of the friction
ring by centrifugal force as it revolves in its containing recess or box. The chief
object of my invention is to provide means for maintaining the friction ring concen-
tric with its containing recess or box and to prevent it from being opened out by
centrifugal force when the clutch is not in action.
In order to hold the friction ring concentric or central with its containing recess or
box I mount it on a frame or series of arms keyed on the revolving shaft the said
frame being fitted into the said ring with just so much play as will allow the latter
to be quite free of its recess or box when contracted or collapsed so as to bear on the
outer periphery of the said frame or on the outer ends of the aforesaid arms by which
it is also caused to revolve.
In order to prevent the friction ring from being expanded by centrifugal force as
it revolves when the clutch is out of gear I make it as a spring having a tendency to
collapse on to the supporting frame or arms above mentioned; but when fitting it
into its recess or box I open it out against the aforesaid spring action, and turn it,
when so opened out, to the proper diameter to fit into its recess or box. By these
means when the ring is expanded by means of the wedge or otherwise in the usual
way it fits accurately against the internal cylindrical wall of the recess or box so as to
exert its frictional action evenly all round the circumference of the same; whilst
when the ring is allowed to collapse by the withdrawal of the wedge or other operating
device it does so by its own spring action in opposition to and superior to the
centrifugal force which tends to expand it.
I fit the wedge, by which the friction ring is expanded when the clutch is to be
put in gear, into the aforesaid frame or into one of the arms carrying the said ring so
that it acts radially against the inclined ends of the said ring and I operate the said
wedge by means of a lever mounted in the said supporting frame or arm and pin
jointed to the said wedge; the said lever being actuated by means of a toggle joint
so arranged that an extremely small pressure end wise of the shaft suffices to impart
sufficient pressure to the wedge to cause the friction ring to expand and to grip, by
friction, the inner circumference of the recess or box in the pulley or on the shaft
to which it is desired to communicate motion. The abovementioned toggle may be

page_text: operated by a sleeve sliding longitudinally on the shaft and moved to and fro thercon
by means of levers and forks in the usual way, and it is preferably so arranged that
when the clutch is put in gear by its means it shall so stand with reference to the
wedge actuating lever that the reaction of the latter cannot force the toggle to
release the clutch, so that the latter is held in gear automatically. The above
described arrangements for actuating the wedge prevent the latter from being forced
outwards by centrifugal force when the clutch is out of gear and thereby prevents
it from applying the friction ring when not required.
Dated this 23rd day of October 1888.
•
COMPLETE. SPECIFICATION.
Improvements in Friction Clutches.
I, SAMUEL FORD, of 139 Hartington Road, South Lambeth, in the County of
Surrey, Engineer, do hereby declare the nature of the said invention and in what
manner the same is to be performed, to be particularly described and ascertained in
and by the following statement, reference being had to the accompanying two sheets
of drawings and to the letters and figures marked thereon, that is to say:-
This invention relates to that kind of friction clutch in which a split metallic
friction ring, contained within a cylindrical recess or box, is pressed outwards against
the internal cylindrical walls of such recess or box by means of a wedge pressed
between the split ends of the said ring when it is desired to bring the clutch into
action, and is drawn away from or out of contact with the internal cylindrical wall
of such recess or box by means of its own elasticity or otherwise when it is desired
to throw the clutch out of action.
In the friction clutches of this kind heretofore in use there have not been, so far as
I am aware, any efficient means for maintaining the. friction ring concentric with its
containing recess or box when the clutch is thrown out of action, but that on the
contrary the said ring is liable at that time to come in contact, at some point or other
of its circumference, with the interior of the said recess or box, and to rub against
the same as it or the said recess or box revolves, thereby producing friction which
causes the parts of the clutch to become hot. To prevent this heating, lubrication is
often applied to the parts which come in contact, with the result that when the clutch
is required to be used its action is impaired by the presence of the lubricant between
the frictional surfaces. Similar effects are sometimes produced by the opening out of
the friction ring by centrifugal force as it revolves in its containing recess or box.
The chief object of my invention is to provide means for maintaining the friction
ring concentric with its containing recess or box and to prevent it from being opened
out by centrifugal force when the clutch is not in action.
Figure 1 of the drawings is a sectional elevation taken on the line W W of
Figure 2 of a friction clutch constructed in accordance with my invention, and
Figure 2 is a sectional elevation of same taken on line X-X of Figure 1.
In order to hold the friction ring A concentric or central with its containing
recess or box B which turns loosely on the shaft D, I mount it on a frame or disc
of approximately the same form as the interior of the ring A but preferably on a
series of say four arms or projections C, C, C, C keyed on the revolving shaft D
the said frame disc or series of arms C C C C² being fitted into the said ring A so as
to allow the latter to be quite free of its recess or box B when contracted or collapsed
so as to bear on the outer periphery of the said frame or disc, or on the outer onds
of the aforesaid arms CCC C². The ring A is also caused to revolve by means of
one of the said arms (C' in Figure 1) which takes into a recess or slot formed in the
said ring preferably at a point diametrically opposite to that at which the actuating
wedge E is placed.
In order to prevent the friction ring A from being expanded by centrifugal force

page_text: as it revolves when the clutch is out of action, I make it as a spring having a
tendency to collapse on to and to bear on the periphery of the supporting frame or
on the ends of the arms C C C C but when fitting it into its recess or box BI open
it out against the aforesaid spring action, and turn it, when so opened out, to the
proper diameter to fit accurately into its recess or box B. By this means, when the
ring is expanded by means of the wedge E or otherwise in the usual way, it fits
accurately against the internal cylindrical wall of the recess or box B so as to exert
its frictional action evenly all round the circumference of the same; whilst, when the
ring A is allowed to collapse by the withdrawal of the wedge E or other operating
device, it does so by its own spring action in opposition to and superior to the
centrifugal force which tends to expand it and comes to bear on the periphery of the
supporting frame or disc or on the ends of the arms C C C C³ so as to be carried or
supported thereby in a position concentric with the frictional surface of the recess or
box B and out of contact therewith.
I fit the wedge E, by which the friction ring is expanded when the clutch is to be
put in action, into a slot in the aforesaid frame, or into one of the arms carrying the
said ring so that it acts radially against the inclined ends A¹ of the said ring in a
manner well understood in connection with clutches of this kind, and I operate the
said wedge by means of a lever F fulcrumed at G to the aforesaid supporting frame
and pin-jointed at N to the said wedge E. The said lever F is preferably actuated
by means of a toggle link I pin-jointed thereto and to a collared sleeve J sliding
lengthwise on the shaft D an arrangement by which an extremely small pressure
end wise of the shaft suffices to impart sufficient pressure to the wedge E to cause the
friction ring A to expand and to grip by friction; the inner circumference of the
recess or box B formed in the pulley or other part to which or from which it is
desired to communicate motion. The abovementioned collared sleeve which operates
the toggle link I is moved to and fro on the shaft D by means of lovers and forks or
otherwise in the usual way. The toggle link I is preferably so arranged that when
the clutch is in action the said link stands in such position with reference to the
wedge actuating lover F that the reaction of the latter cannot force the toggle link I
to release the clutch, so that the latter is held in action automatically; that is to say
that when the sleeve J is moved to the right in Figure 2 to press the wedge E
outwards and thereby to put the clutch in action, the link I is brought to stand nearly
at right angles to the shaft D so that pressure exerted by the outer end of the lever f
on the link I can have little or no effect to move the sleeve J to the left so as to draw
the wedge Einwards and thus put the clutch out of action.
K is a cover plate secured to the frame or arms CC C¹ ª² to prevent the entranco
of dust or dirt into the recess or box B.
The above described arrangements for actuating the wedge also prevent the latter
from being forced outwards by centrifugal force when the clutch is out of action and
thereby prevents it from applying the friction ring when not required. It is obvious
that other means may be employed instead of the wedge E for expanding the friction
ring A but they form no part of my invention.
Figures 3 and 4 of the drawings are sectional views of a similar clutch, but
instead of the lever F being pin-jointed to the wedge E, as shown in Figures 1 and 2,
it passes through a slot E² in the stem E of the wedge E and acts on the ends of
the said slot to move the wedge E outwards or inwards. For convenience of
manufacture, the stem E of the wedge E may be made cylindrical and fitted into a
cylindrical hole bored in the part of the frame supporting the friction ring A, a
slot E3 being made through the said frame, corresponding to the slot in the stem E
for the passage of the lever F.
Similar letters of reference relate to like parts in all the Figures of the drawings.
The above descriptions refer to the clutch as applied for the purpose of transmitting
motion from the shaft D to a pulley, toothed wheel or other instrument connected
with the recess or box B; but it is obvious that the same arrangements are applicable
for the purpose of transmitting motion from a pulley wheel, or other part with which
the recess or box B is connected, to the shaft D.

page_text: Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
First The frame, disc or series of arms or projections CCC C² secured to the
shaft D, for the purpose of supporting the friction ring A of a friction clutch con-
centric with, and out of contact with the frictional surface of the recess or box
containing it, while the clutch is out of action, substantially as herein before described,
and illustrated in the Drawings hereto annexed.
Second-In a friction clutch the construction of the friction ring as hereinbefore
described, and for the purposes specified.
Third In a friction clutch the combination of a friction ring constructed as
hereinbefore described, with a frame, disc or series of arms or projections for sup
porting the said friction ring concentric with and out of contact with the frictional
surface of the recess or box containing it, while the clutch is out of action, substan-
tially as herein before described, and illustrated in the drawings hereto annexed.
Dated this 23rd day. of July 1889.
S. FORD.
Per W. H. Beck,
115, Cannon Street, London, E.C., Agent.