Improvements in Friction Clutches.
Year: 1891

page_text: Date of Application, 10th Mar., 1891-Accepted, 11th Apr., 1891
COMPLETE SPECIFICATION.
Improvements in Friction Clutches.
I, ALEXANDER EPHRAIM BROWN, of Corner Hamilton and Belden Streets,
Cleveland, State of Ohio, U.S. of America, Civil and Mechanical 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:-
My invention relates to that species of friction clutch which involves the use, in
some manner, of a curved band, or nearly annular fillet, the circumferential surface
of which (or more commonly a portion of the surface of which) is moved into
forcible contact with the peripheral surface of the part, or device, to be driven
(whenever it may be desired to drive such part) and is, in some manner, moved out
of contact with said part whenever the latter is to remain motionless.
In all friction clutches of this species, or type, as heretofore made, it has been
necessary, in order to move the band-like clutch-device into and out of the clutching
position, or condition, to have a considerable amount of movement in the clutch-
operating lever or other device; in order to assure the complete releasement of the
clutch-band from contact with the part to be released from the influence of said
clutch-band, throughout the entire extent of its friction-creating surface, and, under
many conditions, or circumstances, this necessary extent of movement is more, or
less, objectionable.
Another defect, or objection, to this species of friction clutch, has been that, in
throwing the band into gear, a portion of its contacting surface has usually had to
move in a direction opposite to that in which travelled the surface to be engaged by
said band; the consequences of which, have been a tendency on the part of the
band to chatter and a loss of power and motion in the effort to contact such portion
of the band with the thus repellant, opposing, surface.
I propose to provide for use, a friction clutch device, or mechanism, of the type
alluded to, in which the novel principle of construction and mode of operation are
such that, while I am enabled to quickly throw the clutch mechanism into an
operative condition, with the minimum extent of motion to the movable parts, or
devices, and without any repellant action on the part of the band, I can also, with
the minimum extent of operative movement, completely and perfectly separate the
contacting surfaces of the movable and stationary parts of the clutch levice,
throughout the whole extent of said surfaces and nearly, or quite, simultaneously
at every point therein, while at the same time, I attain to the greatest possible
extent of perfection in the particular of the efficiency of a friction clutch device,
of the type mentioned.
To these main ends and objects, my invention may be said to consist, essentially,
in the novel devices, and combinations of parts, which will be found hereinafter
explained and which will be more specifically pointed out and more clearly defined
in the claims of this Specification, and the leading, or cardinal, point of novelty in
which is, a friction-band movable, circumferentially, throughout the entire length of
its contacting surface.
To enable those skilled in the art to which my invention relates to make and use
the latter, I will now proceed to more fully describe my invention, referring by
letters to the accompanying drawings, which form part of this Specification and in
which I have shown my said invention carried into effect in those precise forms of
clutch-mechanism in which I have, so far, successfully practised it; although, of
course, other modifications, than those herein shown and described, may be devised
and employed without departing from the spirit of my invention.

page_text: In the drawings,
Fig. 1, is a face view, or elevation, of a friction clutch, embracing my
improvements.
Fig. 2, is a sectional elevation of the same, taken at the line - of Fig. 1.
Fig. 3, is a similar sectional view, or elevation, but taken from an opposite point
of view and at the line y-y of Fig. 1.
Fig. 4, is a face view, showing only the drive-shaft and the clutch-band segments
which are mounted thereon, together with the clutch-band proper and the adjusting
wedges, or devices, by which said segments are relatively oscillated about the drive-
shaft.
Fig. 5 is another face view, or elevation, of my improved clutch device, or
mechanism, but drawn on a somewhat larger scale than the preceding figures and
showing a modification of the mechanism, in which the relatively movable segments
are operated upon by means of a screw-stud having a right and left-hand thread,
and worked through the medium of a rocking-arm, or lever, connected with the
sliding-collar of the clutch mechanism.
Fig. 6, is a sectional elevation of the modified form of clutch mechanism
partially shown at Fig. 5; the parts drawn in section representing the appearance
of said parts as cut through, on the lines x- and y-x, of Fig. 5.
Fig. 7, is a partial sectional elevation, or face view, of still another modification
of the clutch mechanism; and
Fig. 8, is a detail view, showing in perspective and on a slightly enlarged scale
the two end portions of the clutch-band proper, detached from the other parts of
the device.
In the several figures, the same parts, wherever they are duplicated, will be found
designated by the same letter of reference.
Referring now to Figs. 1 to 4, inclusive, of the drawings, A, represents a drive-
shaft from which it is proposed to impart power and motion, on such occasions as
may be desired, to the pulley, or wheel, B, that is supposed to be mounted loosely
on said rotatory shaft. This wheel B, is made hollow, or dish-shaped, as clearly
shown, (and as is customary in making such wheels of a clutch mechanism), and,
within the dish-shaped portion of said wheel, is mounted another wheel (or the
greater portion of a wheel), that is composed of two portions, or segments, C and C³,
which, as shown, are mounted, one loose and the other fast, on the shaft A and are
capable of more, or less, movement, relatively, about the axis of said shaft as a
centre of such relative movement; and, on the periphery of this duplex wheel, or
these segmental devices, C and C2, is arranged the friction-band proper E, which as
shown, is partially seated within the circumferentially formed recess, or recesses, in
the said parts C and C2, and which is formed, or provided, at its adjacent (and
nearly meeting) ends, with obliquely arranged projections, or block-like portions i,,
(see Figs. 1 and 4,) which are seated in and are capable of sliding, bodily, within
obliquely arranged cavities, or recesses, formed in two of the adjacent, end-portions
of the segments C and C2; all as clearly shown.
h, h, and h², h², are four set screws, arranged, as shown, in pairs and mounted in
threaded holes in the arm-like portions of the segments C and C², for the purpose
of constituting, at their opposing, or opposite, ends, adjustable, bearing-surfaces,
against which act the opposite working sides, or surfaces, of two wedge-like devices,
marked respectively 1 and 2, (see Figs. 2, 3, and 4,) which project from the arm-
like portione of the clutch-collar d and that operate to force apart the opposing
ends of each pair of the set-screws h, h, and 12, 12, for the purpose of producing the
necessary relative movements of the segments C and C³, to set and unset the clutch-
band; all in a manner to be presently more fully described.
The clutch-collar d is arranged and adapted, as shown, to slide longitudinally on
the drive-shaft A. and has combined with it a collar within which the clutch-
collar dis free to rotate, but by means of which, said collar d is moved bodily
endwise, through the medium of the usual shipper-bar, or handle
which is
pivotally connected, at one end, or point, to some suitable, stationary, bar, or

page_text: fixture D, and which, at the end opposite to that designed to be grasped by the
operator of the clutch mechanism, is connected (at diametrically opposite points)
with the collar f of the clutch mechanism; the said shipper-bar, or clutch-lever b,
being bifurcated, as shown, (see Fig. 1,) so that its ends straddle, or embrace, the
said collar; all in a manner well understood by the skilled mechanic.
The wedge-shaped operating devices, 1 and 2, which, as before remarked, project
from the arm-like portion e of the sliding clutch collar, are made just the reverse of
each other, with reference to the direction of the inclined, operating, faces, or
wedge-like surfaces; that one marked 1, being tapered, as shown, (see Fig. 2,) so
as to be largest at its root portion and smallest at its free end, while the other,
marked 2, is largest at its extreme free end (see Fig. 3), and is tapered so as to be
smaller at its root, or that end which communicates with the arm-like portion e, of
the clutch-collar.
The clutch-band proper, or friction-creating device E, is composed, preferably,
as shown, of a thin metallic band, having securely attached to it an outer and
thicker fillet, or band, of vulcanized fibre, or some other material best adapted to
act as a contacting surface against the internal, circumferential, surface of the dish-
shaped metallic part B of the clutch mechanism, and the obliquely arranged end-
blocks, or club-like end-portions, 1, i, of the concrete clutch-band proper E, are
purposely arranged to fit movably within, and so as to slide inwardly and outwardly
in, the obliquely arranged cut-outs, formed as shown, in two adjacent ends of the
segments C and C2; all in such manner that any relative movement of these
segments operating to further separate those adjacent ends, thereof, to which the
ends of the friction-band are coupled, by means of the end-blocks i, i, will cause
the friction-band to be moved, circumferentially, throughout its entire length and
at the same time expanded radially, at all points throughout its length; while any
relative movements of said segments in an opposite direction, will have a reverse
effect on said friction-band, causing it to be positively contracted, with a combined
circumferential and radial movement; throughout its entire length.
In the operation of a clutch device, or mechanism, such as shown in Figs. 1 to 4
inclusive, and so far described, the clutch is thrown into an operative condition,
by moving the shipper-bar, or handle g, on its fulcrum, in the direction indicated by
the arrow at the lower part of Fig. 2, while to release the contacting devices, or
throw them into an inoperative condition, said lever is, of course, moved in an
opposite direction.
It will be seen that whenever, in thus moving the hand lever y, the clutch collar,
with its laterally projecting wedges 1 and 2, is moved toward the segmental
devices C and C, the wedge 1 operates, by its direct action on the bearer-
screws h, h, to force further apart those portions of said segments in which are
seated the end-blocks i, i, of the clutch-band E, and that thereby said band is
distended, both circumferentially throughout its entire length and radially at all
points, until its outer, peripheral, surface comes into perfect contact with the
internal circumferential surface of the wheel, or device B, to be rotated; the other
wedge 2, at the same time, and to substantially the same extent, permitting the
opposite ends of said segmental devices to approach each other.
And that whenever the said clutch collar is moved further away from the said
segmental devices, then the wedge 2, operates on the bearer screws h2, h3, in such
manner, as to force further apart those end-portions of the segments in which said
bearer-screws are located; the wedge 1, at the same time permitting the opposite
ends of said segments to approach each other.
Hence, the movements of the clutch collar, with its attached, or projecting,
wedge-like devices 1 and 2, operate to positively enforce a relative, oscillating, move-
ment of the segments, C and C2, about an axis of motion co-incident with the
axis of the shaft A, in each one of the two directions in which said segments are
capable of relative motion; and, when moved in one way, the band E, is expanded
positively and when moved the other direction, said band is positively
contracted.
in

page_text: Since the band E, when distended, moves, circumferentially, (and, of course, in
one direction,) throughout its entire length; the greatest extent of motion occurring,
of course, at that end which is coupled to the segment that turns on shaft A, and
the least extent at the other end; and, inasmuch as the said band, when expanded,
forced outward against the contacting surface of B, nearly simultaneously and
with substantially the same degree of pressure at every point, throughout its entire,
external, peripheral surface; and is, when positively contracted, forced, in a like
manner, into contact, at its inner peripheral surface, with the depressed portions of
the peripheral surfaces of the segments C and C; and these portions of said
segment surfaces lie, always, in a circle, concentric to that in which lies the friction
surface of the part B, it follows, as a necessary result, that, in shifting the said
band E, from its extreme state of expansion to its extreme state of contraction,
and vice versa, and in thus changing slightly, its degree of curvature, the least
possible amount of movement in the said band and its distending and contracting
devices, will serve to throw the band into frictional contact with the part B
(to be driven by said band) and perfectly clear thereof, or fully out of contact
therewith.
Hence in my improved clutch mechanism, not only is the friction-band E, when
thrown into gear, moved, at every point of its contacting surface, in the same
direction in which is travelling the surface to be clutched and, when thrown out of
gear, moved at every point, in the direction in which the clutched surface tends to
throw off the said band; but, furthermore, a perfect and efficient clutching together
of the parts and a perfect releasement of the parts, can be effected with the smallest
possible extent of motion in that end of the shipper-bar, or handle g, which has to
be grasped in the hand of the operator.
This is of considerable importance and advantage, especially where the clutch
mechanism may be used in connection with other machinery, certain operating
handles, or hand-levers, of which have to be manipulated simultaneously with, or
in rapid succession relatively to, the shipper-bar of the clutch device; as for
instance, in the case of the use of a friction clutch in connection with the
engine of some of the well known forms, or types, of hoisting-and-conveying
machines.
Another advantageous peculiarity in the principle of construction and mode of
operation of my improved clutch mechanism is that, in those movements of the
parts designed to release, or separate, the surfaces frictionally clutched together,
the clutching surface of the band E, moves away from the contacting surface of
the pulley B, rapidly, and with an initial movement that is nearly, or quite,
radial; and almost simultaneously at all points throughout its entire circumference;
this mode of action being due to the fact that at the initial, relative, movement of
the band-contracting segments C and C2, the end blocks i, 1, tend to slide, or
move, quickly, in the directions indicated by the arrows marked thereon, at
Fig. 4 while, at about the same time, these end-blocks are drawn toward
each other by the circular movement of that one of the segments which turns on
the shaft A.
Of course, it will be understood that in lieu of the precise detail construction
shown, involving the obliquely arranged club-ends i, i, adapted to slide bodily in
their housings in the, relatively, movable ends of the segments, as set forth, some
other means may be adopted which will effectuate the circumferential movement
of the band throughout its entire length and, at the same time, cause it to have
an initial movement almost radial in direction.
By the combination, as explained, of a flexible clutch-band E, with the sur-
rounding, contacting surface of the wheel B and a band-contracting device such as
described, the periphery of which is about concentric to the said contacting surface
and on to which the band is positively (and forcibly) drawn, or clasped, I am
enabled, it will be understood, with the least possible degree, or extent, of motion
of the working, or clutch-operating, parts of the mechanism, to rapidly, completely,
and positively, move the frictionally engaging surfaces of the clutch wholly out of

page_text: contact; and, by making the clutch-band E (no matter what suitable material, or
materials, it may be composed of,) with a sufficient degree of innate rigidity, or
stiffness, said band may be distended, in the manner described, so as to have the
said frictionally engaging surfaces of the clutch mechanism, brought forcibly into
perfect contact throughout the whole extent thereof.
By having the band E capable thus, of frictional contact with the part B
throughout its entire length, the greatest possible degree of efficiency is, of course,
attained to; since, in the band-species of clutch mechanism, the greater the length
of the contacting surfaces of the band, the greater amount of friction there will be,
tending to lock together, the parts to be engaged.
I am not aware of the existence prior to my invention, of any band clutch-
device in which the construction has been such, that the friction-band when either
distended, or contracted, was moved circumferentially (in one direction,) through-
out its entire length; or could be positively expanded, into contact, throughout its
entire length, with one circular surface and also positively contracted on to another
contacting surface (irrespective of which surface might be the one to be clutched),
and I deem these structural features of my improved mechanism, as among its
most important characteristics.
The arrangement I show and describe, of the band within the contacting surface
to be clutched, so that to do the clutching the band is expanded, or distended, is
the preferable one; because, there are, in the mechanism, no over-hanging, or over-
reaching, parts such as are necessary where the band is carried by the outer
device and has to be contracted on to the surrounded pulley, or device, to throw
the latter into motion; but, under either arrangement, the characteristic features
above alluded to may be introduced into the clutch mechanism.
It will be seen that in my improved clutch, there is a constant tendency in the
friction-band to move bodily and radially away from the clutched surface and that,
therefore, the unclutching operation can be effectuated with the greatest ease and
rapidity, no matter under how great strain the band may be held against the
surface with which it may be in engagement.
By the combination with the band-expanding and contracting segments, of the
wedge-like devices shown, operating as described, a very simple, durable and
efficient contrivance is produced and for clutches of small size, I consider the
specific means I have so far described for actuating these segments, an important
part of my invention.
At Figs. 5 and 6, the modified construction shown is one in which the clutch
collar d, instead of being provided with two operating wedges, to act on the
relatively movable segments C and C2, has a portion e, to which is pivotally con-
nected one end of a link, or short rod f, the other end of which is coupled to the
free end of a vibratory arm g, that is made fast, at its other end, to the small
rock-shaft a².
This rock-shaft a³, is threaded on opposite sides of the attached arm o², the
screw on one part being right-handed, while that on the other part is left handed
and each of these, differently threaded parts engages with a female thread, to match
it, cut in a cylindrical block, or nut m², (see Fig. 5,) mounted, so as to be capable
of a slight amount of motion axially within its seat, in the segment with which it
is connected.
In the operation of my improved clutch, under the modified construction shown
in these two Figures (5 and 6), the movement of the shipper-bar, or hand-lever g,
in one or the other direction, causes the sliding-collar d, through the medium of its
attached arm-like portion e³, and the connecting-rod 2, to vibrate, in one direction,
or the other, the arm g³, and such movements of said arm, cause the rock-shaft a*,
to be oscillated on its axis. Any such oscillatory movement of the said shaft
causes its screw threads, of course, to either screw into and thus draw toward each
other, or to unscrew out of, and thus force further apart, the nut-blocks m², m³, and
thus the end portions of the segments C and C2, in which said nut-blocks are
mounted, are either drawn nearer together, or are forced further apart, whereby the

page_text: clutch-band E, is effected in the same manner as in the form of clutch mechanism
illustrated in Figs. 1 to 6 inclusive of the drawings.
The means for operating the segments seen at Figs. 5 and 6, I have found
to work well and I deem it preferable to the first described means, for clutches of
large size.
At Figs. 7 and 8, is shown still another modification with reference to the means
employed to work the clutch band.
In this form of machine, there is employed, in lieu of the two segments C and C³,
shown in the other views, a complete, single, band-wheel C', which is, preferably,
of that form which comprises a cylindrical hub, an annular rim, and a series of
radially arranged arms, or spokes, connecting the said hub and rim.
There is an omission, however, of one of the arms, to make room, as shown, for
a band-operating arm R that is pivoted, or mounted, at its inner end, on the
shaft A and that is formed, or provided, at its outer end, with an engaging lug r
that enters the obliquely located aperture et, (see Fig. 8) in and near one end of the
friction band E for a purpose to be presently explained.
In the outer end of the arm R, is mounted so as to be capable of a slight turning
movement, a nut-block m³, and in one of the nearest two arms of the wheel C, is
similarly arranged another such nut-block, all as clearly shown; while in engage-
ment with the female threads of these two nut-blocks are the right and left handed
threads of a rock-shaft a², similar to that previously explained and shown in Figs. 5
and 6 and provided with a vibratory arm g², which is supposed to be moved, at
pleasure, in either direction by means (not shown at Figs. 7 and 8), the same as
that seen at Figs. 5 and 6 and hereinbefore fully described.
In the construction shown at Figs. 7 and 8, that end of the brake-band E that
has two oblique depressions, or cut-outs es, at the edges of the band, (see Fig. 8) is
movably secured to the peripheral surface of the wheel C4, by means of two,
obliquely, located, lug-like projections e, which enter, or engage with, the said
recesses, e; and, in the operation of the working parts, whenever the free, or
outer, end of arm R is moved further away from that one of the arms of wheel C4,
in which is mounted one of the nut-blocks m², that end of the friction-band E that is
coupled to said arm (by lug and hole e',) is of course, forced away from the other
end of the band so that the latter is expanded and forced into frictional contact
with the surrounding internal circumference of the rim of the wheel B to be
clutched and driven; the expansion of the band E in this modification of my
improved clutch, being effected, however, by the movement, bodily, in a circum-
ferential direction, of the band; the whole action and the movements of the said
band, being substantially the same as in the cases shown in the other figures; since,
notwithstanding the fact that one end is coupled (by the lugs c', and the
recesses e) to the complete wheel C, said end of the band E, moves initially in a
nearly radial direction away from its peripheral seat in the wheel C, and against
the surface of B, to be clutched, all in a manner quite analogous to that peculiar to
the other shown forms of my improved clutch.
As indicated by the dotted lines at Fig. 7, the central, or hub, portion of the
wheel C, is cored out, or cast with a laterally extended cavity, or housing, through
which the perforated end of the arm R, is passed, in order that the arm may
occupy a proper position, relatively to the perforated hub of the wheel, in the
manner shown, and the said wheel and arm are then threaded, (so to speak,) on
the shaft A.
Having now particularly described and ascertained the nature of my inven-
tion, and in what manner the same is to be performed, (either as to some only,
or as to all of the said structural features, and wishing it to be understood that I do
not limit myself to any precise details of construction, not essential to the essence
of my invention,) I declare that what I claim is :-
First. The combination with a suitable shaft and a wheel, or part, mounted
loosely thereon and adapted to be acted upon by a frictional clutching-band, of a

page_text: clutch-band which is movable circumferentially throughout its entire length;
means by which said clutch band is positively expanded, or distended, against
the contacting surface of said wheel, or part, with a combined radial and
circumferential movement throughout its entire length; and means by which said
clutch-band and its attachments are caused to rotate with the said shaft; sub-
stantially as and for the purposes set forth.
Second. The combination with a suitable shaft and a wheel, or part, mounted
loosely thereon and adapted to be acted upon by a frictional clutching-band, of a
clutch-band which is movable circumferentially throughout its entire length; means
by which said clutch-band is positively expanded, or distended, against the con-
tacting surface of said wheel, or part, with a combined radial and circumferential
movement throughout its entire length and by which said clutch-band is also
positively contracted, with a similar combined movement; and means by which said
clutch-band and its attachments are caused to rotate with the said shaft; sub-
stantially as and for the purposes set forth.
Third. In a friction clutch mechanisın, the combination with the wheel, or part,
to be clutched to the drive-shaft, and the part having a circular surface which is
concentric to the surface of the said wheel, or part, to be clutched and that rotates
with the said drive-shaft, of a clutch-band which is positively expanded and con-
tracted, with a combined radial and circumferential movement throughout its
entire length; and means operating to thus expand and contract said clutch-
band, respectively, against the contacting surface of the wheel, or part, to be
clutched and against the concentric contacting surface of the said part that
rotates with the drive-shaft; substantially as and for the purposes set forth.
Fourth. In a friction clutch mechanism, the combination with the wheel, or part,
to be clutched to the drive-shaft; a frictional clutch-band movable circumferentially
throughout its entire length; and the parts which are fast on the drive-shaft and
carry said frictional clutch-band, of means operating to move the said clutch-band
circumferentially and also radially, throughout its entire length, and operating,
when in action, to exert a constant tendency to thus move the clutch-band in both
a radial and a circumferential direction; all substantially as and for the purposes
set forth.
Fifth. The combination with the wheel, cr part, to be clutched to the drive-shaft
and with the parts which rotate with said shaft, of a friction-band movably secured
to said rotatory parts, a sliding-collar, or device, arranged on the drive-shaft; and
wedge-like devices having their tapering surfaces arranged relatively in an opposite
manner and operating to positively oscillate said rotatory parts to expand the
clutch-band and also to contract it; the whole constructed and operating sub-
stantially as hereinbefore set forth.
Dated this 20th day of December 1900
H. D. FITZPATRICK,
70, Wellington Street, Glasgow, Agent.