Improvements in Friction Clutches.
Year: 1891

page_text: Date of Application, 23rd Sept., 1891-Accepted, 24th Oct., 1891
COMPLETE SPECIFICATION.
Improvements in Friction Clutches.
I, HERBERT JOHN ALLISON, of 52 Chancery Lane, London, in the County of
Middlesex, Patent Agent, do hereby declare the nature of this invention (which
has been communicated to me from abroad by Henry Pithie Christie, of 'San
Francisco, in the County of San Francisco, and State of California, United
States of America, Engineer), and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:
My invention relates to that class of mill gearing wherein wheels or pulleys are
engaged and disengaged by means of frictional contact, and to a method of supporting
and maintaining in alignment such pulleys and wheels when they are not in motion,
or use, without any running joints or bearings when the frictional surfaces 'are
disengaged; also, to increasing the area of such surfaces, and balancing the 'strains
thereon.
The invention consists in providing at both sides of pulleys or wheels annular
supports or bearings, the diameter of which is great enough to permit the friction
clutch mechanism to pass through these bearings, and to operate therein; the
wheels or pulleys having no support on, and consequently no connection with the
driving or driven shaft, except through the medium of the friction clutch when that
is engaged.
It also consists in providing the wheels or pulleys with rims or extensions at their
sides, projecting beyond their faces, so as to form an axial bearing, or support,
when the wheels or pulleys are not in use, such support being, as before said,
independent of the driving or driven shaft to which the friction clutch is applied.
It consists further, in forming on both sides of wheels or pulleys annular ledges,
or rings, provided with angular grooved jaws attached to the spokes or web of such
wheels or pulleys, facing outward from the center plane of rotation, and into which
fit corresponding angular faced rings or ledges on the clutch, revolving with the
shaft.
My invention also includes mechanism for pressing these opposite frictional
surfaces together by means of toggle joints, consisting of bell cranks and links, 80
the pressure will be balanced and equal on each side of the pulleys or wheels, and
on each of the angular grooved faces, and so the driving force will fall on the
spokes or webs, the same as if the pulleys or wheels were mounted on and driven by
a central hub, or boss, keyed to a shaft.
Referring to the drawings, in which similar letters of reference indicate corre-
sponding parts:
and
Fig. 1 is a side view of one of my improved clutches applied to a band pulley,
Fig. 2 is a section through Fig. 1, on its central axis or plane of the driving
shaft.
'The pulley A, is mounted and sustained, when not in use, on two strong
brackets, B1 and B2, by means of the flanges or rings C₁ and C', which are turned
so as to fit loosely in the brackets B1 and B2, forming an axial support.
These brackets, B1 and B2, are bolted firmly.at their base, as shown, and are also
connected by struts and bolts at N, so they are held rigid and parallel. Within
the flanges or rings C' and C2, and attached to the spokes of the pulley A, are
angularly grooved ledges D' and D³, into which fit correspondingly angular
rims E and E, formed on the inner faces of the plates F' and F' of the friction
clutch.

page_text: These plates, F1 and F, are formed integrally with the bosses, or hubs G¹ and G³.
which fit loosely on the shaft H, and are prevented from turning thereon by means
of the keys or feathers I.
To engage the rims or faces E' and E, the plates F1 and F2, are drawn together
in the following manner :
On the boss G2, is placed a sliding sleeve or collar J, in which there is a groove
and a loose ring K, Fig. 2. To this ring can be attached a lever, or other mechanism,
to slide the sleeve or collar J, on the boss G³.
As this sleeve or collar J, is moved out, or in, the adjustable struts a, press
outward, or draw inward, the horizontal arm n, of the bell crank c, which have
their fulcrums ate on the plate F2. This causes a corresponding strain on the
links m, which are attached to the plate F', at i, as shown in Fig. 2.
In this manner the angular faces on each side are caused to grip with equal
force, opposing each other in the same plane, and there are no other strains set up
except in the toggle gearing, composed of the members a, c and m, and their
connections.
Supposing the pulley A, to be at rest; as soon as the clutch is put into the
position shown in Fig. 2, the angular faces at E' and E, grip the pulley A, and
it begins to revolve the shaft H, receives its weight, and also the strain of the
band and centers the pulley A. on the shaft, leaving the brackets entirely clear
of same.
When the collar or sleeve J, is moved out on the boss G2, the adjustable
struts a, pivotted at, are shortened by their angular position, and the two
plates F and F' are forced apart by means of the bell crank c, and link m,
disengaging the angular faces of the clutch, permitting the pulley A, to stop and
take its bearing in the brackets B' and B2, as at first described.
The amount of pressure or the driving power of the clutch is regulated by
means of the nuts on the strut a, which permit adjustment as to length, as shown
in Fig. 1.
In this manner it will be seen that when the pulley A, is stopped there is no
running contact in the mechanism anywhere except the collar K, employed to move
the sleeve or collar J, and this having no strain upon it, there is no wear and no
lubrication required, as in the case when the pulley A, is mounted with its bearing
on the shaft.
It may also be noticed that the strains throughout are controlled and balanced
in respect to all moving pieces.
It will also be understood that the sustained brackets B1 and B2, can stand on
a floor or foundation, as shown in the drawings, or can be fastened to a ceiling or
wall, as the requirement may be; their position around the axis not affecting in
any way the operation of the clutch.
The mechanism shown, and the method of its operation is applicable to wheels,
pulleys or sheaves. A band pulley is selected in the present case as the most
familiar application. The same mechanism is also applicable to either a driven
or driving pulley, except that in the first case when the pulley A, revolves on
the brackets B1 and B2, when out of use, the bearing areas C' and C³, are much
larger and more carefully fitted.
I do not confine my invention to the exact form of the angular friction faces.
These may be modified to suit the amount of strain or work, and in cases where
the strain is light, radial faces can be employed without changing the nature and
object of my invention.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
First. In a friction clutch, the stationary brackets B1 and B2, arranged with
bearings to receive and support a wheel or pulley around and independent of the

page_text: driving shaft, so that when the clutch is disengaged the wheel or pulley will come
to rest and be sustained out of running contact; substantially in the manner and
for the purposes set forth and described.
Second. In a friction clutch, a pulley or wheel A, having bearing collars or
rings C1 and C2, mounted and running loosely in the stationary brackets B' and B',
in connection with a central driving shaft H, and a double friction clutch placed
inside the brackets B' and B'; substantially in the manner and for the purposes
specified.
Third. In a friction clutch, the brackets B' and B', a wheel or pulley A,
mounted loosely thereon, and provided with friction grooves at each side as shown,
so the wheel or pulley when disengaged will take its bearing on the brackets Bi
and B, independent of the driving shaft in the center; substantially as herein
shown and described.
Fourth. In a friction clutch, the wheel or pulley A, provided at both sides with
friction grooves, the two plates F1 and F', engaging therein, by means of toggle
gearing, so the pressure and driving force will be divided equally on each side of
the wheel or pulley A; substantially as herein shown and specified.
Fifth. In a friction clutch, the pulley A, formed with supporting rings or
sleeves C¹ and C³, to give axial support when the wheel or pulley is not in use, and
in combination therewith, frictional surfaces within and covered with the sleeves or
rings C and C, and applied on each side, so the driving strains will be controlled
and balanced; in the manner substantially and for the purposes herein set forth
and described.
Sixth. In a friction clutch, in combination with a wheel or pulley A, the
plates F and F, actuated by toggle gearing, as shown and arranged, to grip the
wheel or pulley A, at both sides of its arms, with an equal and balanced pressure;
substantially as shown and described, and for the purposes specified.
Seventh. In a friction pulley, the two movable gripping plates F1 and F",
provided with jaws E' and E', facing each other and at each side of the driven
wheel or pulley A; the bell crank c, link m, and adjustable strut a, the whole
combined and operating substantially in the manner and for the purposes as set
forth and described.
Dated this 23rd day of September 1891.
ALLISON BROS.,
Agents for the Applicant.