Improvements in Friction Clutches.
Year: 1892

page_text: COMPLETE SPECIFICATION.
Improvements in Friction Clutches.
A communication by HARRY WILLARD HILL, of Waverley Avenue, Cleveland,
in the State of Ohio, United States of America, Manufacturer.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for
Foreign Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street,
Manchester, both in the County of Lancaster, and 323, High Holborn, in the
County of Middlesex, Civil 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:-
This invention relates to the class of friction clutches in which a pair of radially.
movable jaws are mounted on each clutch arm, and are moved simultaneously
toward or from each other and an interposed cylindrical flange for the purpose of
grasping or releasing the same.
The improvements relate to the mechanism for operating the jaws; to the form
of the jaws, and of the clutch arm; to the combination and relative arrangement
of the jaws, clutch arm and operating mechanism; to the means for adjusting the
throw of the jaws and of regulating their movement relative to each other and to
the flange.
The chief objects my correspondent has sought to attain are to simplify, the
mechanism of this class of clutches, to cheapen their first cost, and to render them
less liable to accidental injury without in any manner impairing their efficiency.
It is well understood in this art that this class of mechanism may be employed
to connect a shaft and a pulley or gear loosely mounted thereon, or to couple
together two shafts arranged in the same axial line. In the former case the
cylindrical flange is secured to the pulley or gear; and in the latter case, the flange
is supported by suitable arms on one shaft while the jaws and their operating
mechanism are connected to the other shaft in proper relation to said flange. The
latter construction is illustrated in the drawings of which ;-
Figure 1 is a plan view of a four arm clutch.
Figure 2 is a side view of which one half is in section.
Figure 3 is a sectional view on the line 3-3 of Figure 2, of the clutch jaws,
their operating mechanism and the outer end of the clutch arm.
Figure 4 is a side view of the jaws, disconnected from all of the operating
mechanism except the lever G.
Figure 5 is a sectional view through the arm and the parts mounted thereon, at
the point indicated by the line 5-5 of Figure 2.
Figure 6 is a sectional view through the arm and the parts mounted thereon at
a point indicated by the line 6-6 of Figure 2.
Figure 7 is an end view of the inner jaw.
Figure 8 is an end view of the outer jaw.
Figure 9 is an enlarged section through one of the clutch arms and the clutch
mechanism on line 9-9 of Figure 1 ; and
Figure 10 is a side view of a part of one clutch arm at the point of connection
between it and lever G.
Referring to the parts by letters, A represents a cylindrical flange supported by
arms a, which radiate from a hub a' fast upon the shaft F.
Fixed upon the shaft F1 is the clutch frame having as many radial clutch
arms B as it is desired to employ pairs of jaws and associated mechanism.
Each of these arms, and the mechanism supported thereon, is like every other
arm and the mechanism which it supports; therefore a description of one will
answer for all.

page_text: The arm B consists of two side bars b b and an integral web which is substan-
tially crescent shaped in transverse section, the jaws being mounted on the arm
facing its concave side. This web adds strength to the arm, and at the same time
it hides and protects from injury from the outside the mechanism supported
by said arm. The proximate faces of the side bars bb. are grooved longitudinally
in a part of their length, as shown in Figure 6; and the side edges of the jaws lie
in these grooves whereby they are guided in radial paths.
The outer jaw C is provided with a shank c and a concave flange c¹ which is
adapted to engage with the outer periphery of the flange A. The inner jaw D is
provided with a shank & and a convex flange which is adapted to engage with
the inner periphery of the said flange. The side edges of the shanks c and d lie
against and move in contact with each other when they are mounted on the arm.
The parts of said shanks between the edges so in contact are curved away from
each other whereby a longitudinal recess is formed between them, substantially as
shown in the drawing; and in this recess the greater part of the operating
mechanism is placed.
The grooves are somewhat wider than the combined thickness of the edges of
the jaws which operate therein, whereby the jaws are permitted to rock slightly;
and thus the flanges c¹ and d¹ are permitted to automatically adjust themselves upon
the cylindrical flange A, if it should get out of true, without any strain on the
shanks of the jaws. In the shank of the outer jaw, a socket is formed in which
one end of a spring coil J is placed. The other end of the coil rests against the
web . The coil exerts an end thrust whereby both jaws are normally held against
the farther shoulder of the grooves b. The normal movements of the jaws are
therefore in straight radial paths.
The lower end of the outer jaw shank is provided with the ears and a toggle
lever H passes between said ears into the recess between the jaws. A pin /
pivotally connects the said ears with said lever at a suitable distance from its outer
end. The inner end of the lever H extends to a point near the shaft, and it is
connected by means of the link L (which passes through a slot in the web of the
clutch arm) to the usual sliding sleeve N.
A
The outer end of the lever H is pivoted to the inner end of the double link I,
and the outer end of the link I is pivotally connected with the inner jaw. The
toggle lever H and link I constitute a toggle which in operation, as hereinafter
explained, moves the jaw flanges toward and from each other. The means shown
for connecting the link with the inner jaw provides for adjusting the throw of the
jaws relative to each other to compensate for wear or for any other purpose.
boss projects from the inner jaw into the recess between the jaws. E represents
an adjustable block having trunnions e e on its side on which the outer ends of the
double link are pivoted. This block E is adjustably connected with the boss d²
by means of the rod K having right screw threads in one part of its length and
left screw threads in another part. One threaded portion engages with the block E
and the other part engages with the boss d. The rod extends from this point
outward to a point where its end may be engaged by a wrench passed through a
hole in the outer jaw. A set screw e² screws endwise into the boss d' against a soft
metal block e which bears against the rod K whereby, when the parts are properly
adjusted, they may be fixed in said relative position.
The parts hereinabove described provide for moving the jaws toward and from
each other, because as the sleeve N is moved toward the clutch frame, the lever H
is swung in such manner that the pivot connecting its outer end with the link 1 is
brought into line with the two pivots which connect said link and lever with the
inner and outer jaws respectively. This results in a movement of the jaw flanges
toward each other; and a contrary movement of the sleeve N causes the jaw flanges
to move away from each other. But unless some means to prevent such action are
provided, both jaws will, under the action of centrifugal force when the clutch arm
is revolving, or of gravity when not revolving, move together outward or inward as
the case may be so that, although the jaw flanges are as widely separated as

page_text: possible, either the outer or inner jaw (generally the latter) will remain in engage-
iment with the flange. Numerous devices may be employed to prevent this dragging
of either jaw as above explained. The mechanism employed and which the drawing
shows, not only prevents the dragging of either jaw, but it also compels the jaws to
simultaneously approach and engage with, and disengage and recede from the
flange. It also serves to so connect the jaws that the effect of centrifugal force or
gravity on one jaw is balanced by the effect of the same force on the other jaw.
And it serves to effect these results whether the flange A be accurately turned to
the intended diameter or not. The means consist of the lever G pivoted to the
clutch arm on an adjustable fulcrum, and pivotally connected on opposite sides of
said fulcrum, with the jaws. M represents a bolt, the unthreaded end of which
serves as the middle pivot or fulcrum of the lever G. This bolt passes through a
radial slot in one of the side bars b of the clutch arm.
m represents a nut, into
which the bolt may be screwed, which lies on the inside of the clutch arm between
it and the lever G. When this nut is loosened, the bolt is free to move radially
outward or inward in the slot b*. To set the lever G at the proper position to
perform its prescribed functions, the jaws are closed upon the flange A, the nut m
being loose during this operation. The lever G will be automatically moved to the
proper position relative to the clutch arm. Then by turning the bolt, the nut mis
tightened and the bolt is rigidly fixed to said clutch arm.. When the jaws are
opened, they not only move apart but they move simultaneously and equally away
from the flange A; and when they are again closed they simultaneously approach
engage with said flange.
and
In closing the jaws, the pivot between the end of the lever H and the link I
moves slightly past the line connecting the pivots which connect said parts with the
jaws, whereby the jaws are locked. The engagement of the sleeve N with the
clutch frame serves as a stop to limit the extent of this movement past the center;
and this stop, is made adjustable by means of set screws O which screw into the
sleeve and strike the clutch frame when the jaws are locked.
While describing the construction of the clutch shown, many of the advantages
arising therefrom have been pointed out. There are however other advantages not
hereinbefore specifically referred to. For example, by the arrangement of the jaw
closing mechanism almost wholly behind the clutch arm and between the jaws,
there are no projecting parts which may be struck, to the injury of the clutch.
Moreover the entire clutch and sliding sleeve can be made to occupy a very small
space on the shaft, and a less space than any other clutch of this class with which
my correspondent is acquainted.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same, is to be performed, as communicated to me by
my foreign correspondent, I declare that what I claim is:
1. In a friction clutch, in combination, a clutch arm, a pair of radially movable
clutch jaws mounted thereon and adapted to engage on opposite sides of a
cylindrical flange, a lever pivotally connected to said jaws, a pin on which said lever
is fulcrumed between said pivotal connections, and a radially adjustable connection
between the fulcrum pin and the clutch arm, whereby said jaw will be caused to
simultaneously approach and engage with, and to disengage and recede from, said
cylindrical flange, substantially as set forth.
2. In a friction clutch, in combination, a clutch arm having a radially slotted side
bar, a pair of jaws mounted on said arm, a bolt, which passes through said slot,
having its head on one side and its nut on the other side of said side bar, a lever
fulcrumed on said bolt and engaging on opposite sides of said fulcrum with said
jaws respectively, whereby the fulcrum bolt will automatically adjust itself on the
clutch arm when the jaws are closed against any interposed cylindrical flange, so
that when said bolt is secured to the clutch arm, the two jaws will thereafter
approach and engage with and release and recede: from said flange, substantially. as
set forth.

page_text: 3. In a friction clutch, in combination, a clutch arm, a pair of clutch jaws
mounted thereon, having curved shanks, thereby forming a recess between the
shanks, a toggle lever pivoted between its ends to the outer jaw, the outer end of
said lever lying in said recess, a link lying in said recess pivoted at one end to the
end of the toggle lever and at the other end to the inner jaw, and suitable
connections between the inner end of the toggle lever and the sliding sleeve,
substantially as set forth.
4. In a friction clutch, a clutch arm, a pair of radially movable clutch jaws
mounted thereon, said jaws being curved substantially as described, whereby a
longitudinal recess is formed between them, a block lying in said recess, and an
adjusting screw threaded rod connecting said block with the inuer jaw, said rod
extending outward in said' recess to a point where it can be reached through a hole
in the outer jaw, combined with a toggle lever pivoted between its ends to the outer
jaw, the outer end of said lever extending into the recess between the jaws, a link
lying in said recess and pivoted at one end to the end of the toggle lever and at the
other end to the said block, and a link connecting the inner end of the toggle lever
with the sliding sleeve, substantially as set forth.
5. In a friction clutch,, a clutch arm having grooved side bars and a connecting
web, a pair of clutch jaws, the shanks of which are slidable upon each other, and are
loosely fitted into the grooves in the side bars, combined with a spring interposed
between the said web and the nearest jaw shank, and mechanism for moving said
jaws towar and from each other and an interposed cylindrical flange, substantially
as and for the purpose specified.
Dated this 3rd day of June 1892
WM. P. THOMPSON & Co.,
Agents for the Applicant.