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Патент USA US2122218

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‘June V23, 1938.
Filed April 29, v19:55
4 Sheets-Sheet -l
J'0/1/1/ SNEED
June 28, 1913s.
.Filed April 29, 1935
'4 Sheets-Sheet 2
June 28, 1938.
4 Sheets-Sheet _3'
Filed April 29;, 1955
2% r
June 28, 1938.
Filed‘ April 29, 1935'
4 Sheéts-Sheet 4
Patented Junev v1938
_ 2,122,218
. PATENT orgies
John Snead, Grosse Pointe Shores, Mich"
Applicatidn April 29,1935, Serial‘ Not-1831i. . '
14 (Claims. "(01. res-1oz)
This invention relates to friction devices and.
more particularly to friction clutches wherein en
Another object of my invention isto' provide a
gagement or disengagement of the ,clutch is
e?ected automatically inresponse to changes in clutch in which the tendency to resist slippage
_ 5 the forces transmitted and the speed of rotation may be adjusted or calibrated was to vary with 5
the speed between determinable and adjustable
limits, and' also in'which the tendency of the
In the present application I will describe my in
clutch to slip in response to shocks or overloads
vention as applied to an automotive vehicle inas
much as my clutch-is particularly adapted to the may within reasonable limits be adjusted to~varyr
10 requirements of such service. However, it will be in substantial proportion to the torgue'trans— 10
understood that my invention may m applied to mitted.
In my invention as adapted to an automotive
‘other ‘uses in other environments.
clutch, I preferably attain the objects enumerated
It is among the objects of my invention to pro
conditions; 1
vide anbautomatic clutch or friction device which
15 will engage and disengage at varying rates de=
above by providing a clutch which may be asso- ,
ciated with the fly wheel of the engine of a motor 15
pending upon variations in speed and load on the car and which preferably comprises a pressure, ‘
‘ clutch. A further object of my invention is to , plate
or driven
by themounted
?y wheel
a vfriction
‘ provide an automatic clutch which will smoothly
, engage under various conditions of speed and load.
20 Another object of my invention is to provide a is preferably moved into engagement by means of 0 .
‘ clutch which will automatically ‘tend to slipwhen centrifugally actuated weights mounted on a cas
overloaded. Another object of my invention is to
provide a clutch in which at least a part of the
driving force is ‘taken through resilient members
which also function to maintain the clutch en
gagement so thatoverloads which e?ect the mem
bers will permit the clutch to slip. Another ob
ject oi’ my invention'is to provide an automatic
clutch having a "simple and effective means for
30 manual engagement and disengagement.
Another object of my invention is to provide an
automatic friction clutch in which within deter
minable limits the pressure between the frictional
elements of the clutch increases as the speed in
1 35 creases and tends to be decreased by torque over
loads whereby smooth clutch engagement and
smooth operation is obtained under all conditions
of speed and load. Another object of my inven
tion is to provide a clutch mechanism which is
. 40 simple in construction, light ‘in weight, compact
in size, economical in manufacture. and durable
and dependable in operation.
It is a further object of my invention to provide
an automotive clutch mechanism which will auto
45 matically permit slippage between the driving and
driven clutch parts in response to shocks or over
loads in the driving mechanism of the automobile
with which the clutch is operatively connected.
Within this object I provide a clutch which pro
50 teots itself and its related mechanism by slipping
or releasing in response to relatively-light shocks
or, overloads under conditions of low speed and
I ' ‘ torque, but which will transmit high torque loads
under conditions of relatively high speed and
55 torque and still be sensitive to provide slippage or
ing which is carried by the fly wheel, the weights
preferably being arranged to act through springs
to rotate the pressure plate with respect to the
casing and fly wheel in a direction opposite to the 25
tendency of the clutch to slip. By means of balls
acting on oppositely disposed inclined planes in
the casing and on the pressure plate, the relative
rotation between the pressure plate and the casing
causes the pressure plate to be moved axially into 3
engagement with the friction disc. The inclined
planes and balls are arranged however so that the
load on the driven clutch part tends to release the
engagement between the driving pressure plate ’
and the driven friction disc, and by this arrange- 35
merit the engagement of the clutch is governed
both by the speed of the motor and by the load on
the clutch, an. increase in speed tending to cause
an increase in the pressure between the pressure
plate andfriction disc and an increase in load 40
tending to cause a reduction in such pressure. By
reason of this construction the rate of clutch en
gagement or disengagement and the engaging
pressures are controlled both in accordance with
speed and load, resulting in a' smooth engagement as
of the clutch under all conditions and resulting in
slippage of the clutch ‘during a condition of over
In a modi?cation of my invention, I provide
manual means for releasing the clutch and means 50
for engaging the driven part of the clutch when
the engine is stopped so that the engine can be
started, in the event of starter failure, by push
ing the car‘ or otherwise rotating the driving
wheels. This last mentioned means may pref- 55
erably comprise a ratchet disc mounted for ro
tation with the driven element of the clutch and
a pawl pivotally mounted on the engine ?ywheel.
The pawl may be urged into engagement with the
ratchet by a spring and the arrangement is such
that the pawl and ratchet mechanism will func
tion to transmit torque only from the driven
member to the driving elements. The pawl may
be pivotally mounted on one of the driving ele
10 ments and is weighted so that when the engine
and will likewise slide the disc forwardly to cause
its forward face to engage with the radial por
tion of the ?y wheel 2 and thus e?ect engagement
of the clutch.
In order to advance the pressure plate 5i into
engagement with the clutch disc H, I have pro
vided speed responsive means mounted within
the casing 2. This speed responsive mechanism
may comprise a plurality of governor weights 30
mounted upon pivot pins 3! which are securely 10
?xed to the rear radial wall of the clutch casing
2. The governor weights are preferably crescent
starts to run, the pawl will by centrifugal e?ect
swing out of engagement with the ratchet against
the force of the spring and under all normal . shape as illustrated in the drawings and are aper
operating conditions will take no part in the tured at one end to receive a pivot sleeve 38
15 function and operation of the clutch.
mounted on the pin 35. The pivot sleeve 38 also 15
In the drawings:
supports a U-shaped spring bracket 32 in which
Fig. 1 is an axial sectional view of a form of
clutch made according to my invention and
adapted for use in an automobile;
Fig. 2 is an end elevation of the clutch mech
anism with parts broken away to show the gov
ernor assembly.
Fig. 3 is a sectional view along line 3-3 of
Fig. 2;
Fig. 4 is an axial section illustrating another
form of clutch constructed according to my in
Fig. 5 is a detailed sectional view of an alterna
tive form of the pressure plate actuating means;
Fig. 6 is a sectional showing of the means
illustrated in Fig. 5 moved to an operative posi
Fig. 7 is a sectional showing of another alter
native form of the pressure plate actuating
Figs. 8 and 9 are sectional and end elevations
respectively of the clutch of my invention pro
vided with a manual release;
Figures 9a and 9b are elevations with parts
broken away showing alternative governor weight
1 constructions;
Figs. 10 and ii are partial sectional and end
elevations of the clutch oi my invention provided
with a means to effect rotation of the prime
45 mover through rotation oi‘ the driven part of the
Referring to the drawings. my clutch mocha»
nlsm as adapted to an automobile or" conven
tional construction may be mounted adj scent the
?y wheel 5 of the motor vehicle engine (not
shown) and may be enclosed within a main
clutch casing 2 provided with‘iorwardly extend
ing annular walls. The outer annular wall is ra
dially flanged at the periphery as at t and may
55 be attached by screws or other suitable means
the side portions of the U are arranged to
tend on either side of the apertured end of
governor weight, the side portions of the U
ing likewise pivoted on the sleeve 38.
To support driving or reaction springs 33,
bight portion of the U-sheped spring bracket 32
is extended beyond the side portions thereof as
at 3% and is provided with a spring supporting
pin 35. The other end of the spring 33 is sup
ported on the governor weight 30 by means of a
spring supporting pin 35 mounted on the pro
jection 39 of the governor weight. The expansion
of the spring 33 is limited by a projection Iii] on the
governor weight which serves as an abutment for
the bight portion of the spring bracket 32. The
bracket 32, governor weight 38 and spring 33 may
be assembled by placing the spring upon the
spring supports 35 and 38 of vthe governor weight
and bracket, respectively, aligning the apertures
in the governor weight and bracket and thenin
serting the sleeve till in the aligned apertures.
The assembly may thenbe placed in the clutch
mechanism by merely slipping the sleeve over the
pin 3i and may be secured thereto by means of 40
a washer or disc held to the pin by screws or
other suitable means as shown, for example, in
Figure 5. It will be seen that the assembly is
free to pivot about the pin 3! as a unit, and the
governor 38 and the bracket 32 may also pivot 45
with respect to each other upon the sleeve 38.
By providing a self-contained‘ sub-assembly of
each of the governor weights with one of the
springs 33 and one of the spring brackets 32 and
one of the sleeves 38, each spring may be given 50
an initial compression in making this assembly
so that there will be no give in the spring until
the load transmitted across it exceeds the initial
compression with which it is loaded; In this
manner I am assured that where it is desired, the
initial motion of the governor weights will be
. The frictional drive in my clutch is prefer
transmitted directly to the pressure plate and in
ably obtained by means of an annular ring or direct proportion to the movement of the gov
pressure plate ii arranged within the compart
ernor weights until such time as the various
to the rear radial wall of the :dy wheel.
ment formed by the casing 2 and the ?y wheel
and is supported therein by the inner annular
wall of the clutch casing 2 for limited movement
Forward axial movement brings the
pressure plate 6 into engagement with a single
forces reacting through the springs 33 exceed GH
their initial compressed load. By the selection
of springs 83 of various characteristics and by
selecting the desired amount of initial compres
sion to impose upon these springs, I can readily
friction disc member H which may be provided ‘ select and predetermine ‘the characteristics of 65
on each face with friction material it! and it, operation of my clutch within a wide range of‘
although it is to be understood that
tion‘ may be adapted to multiple ‘disc clutches
and ‘other types of friction devices. The disc ii
70 is supported at its “center by rivets iii on a hub
' l2 which is spiined to the driven‘ shaft it which
extends rearwardly to. the transmission (not
I shown), It will be seen that forward movement
of the‘ pressure plate ti will cause frictional 'en
75 gagement between the'_,plate 1% and the disc iii
choice. With‘ the results which will hereinafter
more fully appear, I contemplate that the range
of selection of springs 33 may vary from a light
spring having substantially no initial compres
sion on one hand, to a very heavy spring with a
high initial compression or even a solid member
in lieu of the spring 33 on the other hand.
Tocontroi the outward movement of the gov‘
ernor weights in response to‘ the action of cen 75
2,122,213 I
1 trifugal v.iforce, the free‘ end of each governor as the cam and ball assembly in the embodiment
weight is attached to a governor retractor spring - I shown, in Fig. 1 heretofore described in detail;
As illustrated in Fig. 3 it will appear that rota
42- which is preferably anchored to the ‘inner an-v
nular wall of the governor weir‘ifit casing as at 52c. _. tional movement - of the pressure plate 8 with
The effect of the spring 42 ‘i to urge the .gov- ‘ respect to the governor weight casing 2 as indi- '
emor'weight inwardly and tl~J...‘ough the projec cated by the arrow A (counterclockwise as seen in
_ tion '40 thereon. the spring bracket 32 about the Fig. 2) through the cam and ball engagement
pivot pin13l to the innermost radial governor ill-Ei-EZ tends to move, the pressure plate and
:‘ position. _ The inward governor movement’ is easing away from each other and tendsto move
the pressure plate forwardly whereby to fric 10
"limited by the pads '43 of the governor weight con
tacting the inner annular wall of, the governor tionally engage the driven disc between it and the
_ weight casing, while the outward movement may
face of the ?ywheel.
The above mentioned relative rotational move?
be limited byptheyadiusting screws 46 carried in
vment of the pressure plate 6 is produced by the
the outer annularwall of the casing 2.
In order to translate the swinging movement rotation of the clutch casing and ?ywheel as 15
of the governor weights into relative rotational sembly. Centrifugal forcev causes the governor
_ movement between the casing and the pressure weights 30 to swing outwardly about the pivots
plate 4, the pressure plate preferably has ?xed 3i and through the compression springs 3%, spring
thereto adjacent each governor weight and brackets 32, sleeves db, and pins Mi, movesthe
‘ bracket assembly a rearwardly projecting pin til pressure plate t relatively counterclockwise (see 20
preferably surrounded by a square sleeve 45. A " Fig. 2) and to the left as shown in Fig. 3.
The pressure plate 6 is preferably provided with
- ‘?at face of the sleeve” contacts the bight por
p ’ . tion of the spring bracket’ 32 opposite spring 33
‘and has a smooth sliding contact therewith. Piv
otal' movement of the spring bracket 32 will thus
effect a rotational movement of the pressure plate
; iii with respectto the casing 2. .The pivotal move
ment of the brackets 32 in one direction about
the pivots 3! is effected through the springs 33
30 by the outward movement of the governor
weights. Pivotal movement in the opposite di
rection is broughtabout by inward movement of
a'series of ?at leaf springs 5t spaced 'symmetri- -
cally about its perimeter. The springs are pref
erably secured to the forward‘ face of the pressure
plate by screws or other suitable means and the
free ends of the springs slidably bear against the
flywheel i to urge the pressure plate rearwardly
out of contact with the friction disc. As the plate
éi is rotated with respect to the casing 2 the cam 80
and ball reaction at 5t, 5i, and 52 presses the
\ the governor weights or by load reactions on ‘the
plate (i forwardly to produce clutch engagement
against relatively mild resistance by the
'pressurer plate through the' engagement of the
springs 5t.
pins it and the spring brackets 32.
- It will be understood that the clutch during'the
Between the clutch casin 2 and pressure plate I above operation is responsive to torque as well
e forward movement as rotational speed. The transmitted torque, re
of the pressure plate with respect ‘to the casing acting through the disc ii 'and friction member
it tends to induce a relative clockwise rotation
to effect a clutch engagement. _In the embodi
It means are provided to ca
ment of my invention shown in Figure 1 a series
between the pressure plate 65 and the casing 2
of symmetrically spaced cam and ball units are
opposite to that induced by outward movement
preferably employed to accomplish this function.
of the governor weights.
The pressure plate d is provided with a cam 52,
the casing 2 with an oppositely disposed cam 5i
wise movement between. the pressure plate and
easing, as indicated in Fig. 3 by-the arrow B, with
the attendant cam reaction at 5@—-5i-—b2 has an
axial component of movement of the pressure
45 ‘and a steel ball 5i] is arranged between the two
cam faces.
Rotational movement (of the pressure plate ii
' within the governor casing 'Zinay be translated
into axial movement of the pressure plate by
v50 means other than the cam and ball arrangement
This relative clock- '
as __
plate to the right'as shown in Fig. 3 and tends to, >
effect a decrease in the pressure on the plate ii
to permit slippage of the clutch disc ii, between
the ?ywheel i and plate 6%.
illustratedin ‘connection with the above described
embodiment of my invention. Alternative forms
of pressure plate actuators ‘are illustrated in Fig
Referring thus to Figs. 1, 2 and 3, transmitted
torque always tends to move the pressure'plate
d clockwise as shown in Fig. 2, and to the right
ures 5, 6 and 7.
One modi?ed form comprises a link 50 with
the clutch. In opposition to this tendency, the £55
as seen in Fig. 3, i. e., the torque tends to release
centrifugal governor tends to move the pressure
and 62 formed in the casing 2 and the pressure plate d counterclockwise as seen in Fig. 2 and to
plate ii respectively. The link Ed is preferably ' the left as seen in Fig. 3, i.‘ e. the speed of the
provided on one side with a'stop lug 53 to prevent driving member ‘tends to engage the clutch. '
60 effective movement ‘of the link past a dead center These primary forces are directly opposed through W
the springs 33 and the ‘bail and camv construction
rounded end portions positioned in bearings ti
As illustrated in Fig. 6, the lug ttcontacts the
pressure plate when the link til has been moved
by the plate Ii to a position of maximum pres
.65 sure. The transmission of driving torque tends
33 or the circumferential component or result oi’
the centrifugal effect of the governor weights, 6%
to move the casing 2 in the opposite direction with
respect to the pressure. plate It and tends to re
turn the link Bil to or toward a less inclined posi
will cause the clutch to slip without substantially, .
tion as shown in Fig. 5.
engaged or not.
A second modi?cation of clutch actuating
means is shown in Fig. 7 wherein the pressure
plate dis formed with a camo surface 72 and the
casing 2 is formed with a cooperating cam surfacev
‘ii. Auroller ‘iii is arranged between the cams ‘ii
75 and ‘i2 and the assembly functions substantially
50, st, 52. Thus torque loads, for any given
speed, which exceed either the force in the springs '
modifying the amount of torque actually trans
mitted whether the clutch has previously been
In the operation of my clutch as above described, the weights of the governor and the re
tractor springs i2 therefor may be so propor
tioned’ that for F‘idling speeds” of .the driving
member the weights will be held’ against out
ward movement and the clutch held in diseu-_ it
gaged position; any accidental drag or rubbing of
pressure plate 4 and the ?ywheel l. The force of
the pressure plate against the driven disc simply ' drive in the pressure plate is transmitted "through ~
tending to preserve the disengagement oi’ the
clutch under these conditions. As the speed of
the driving member is increased the governor
weights begin to move radially outward and be
gin to impart a’ counterclockwise (as seen in Fig.
2) rotational movement to the pressure plate or
plates with respect to the driving member in the
10 direction of rotation of the driving member; the
force and motion of the governor weights being
transmitted through the springs 33, pins 58 and
cam and ball assemblies 5ii-5l-52, thus induc
ing an axial movement of the pressure plate
15 toward the driven disc. Outward radial move
ment of the governor weights continues the above
the pins 54 and the springs 33. Thesprings 35:‘;
as a group are proportioned to carry substantially:
one-half of the ultimate desired tangential force“
of the drive where, as in Fig. 2 only onemov- 1‘
able-pressure plate is used.
Although I have found the mechanism disclosed
in Figs. 1, 2 and 3 to be very satisfactory in oper
ation both with respect to the smoothness of its 10
engagement and with respect to its sensitivity to
release under overloads or shocks throughout a
wide range of speed and load conditions, I con
template that greater advantages may be ob
tained at least under some conditions by the ap
plication of the principles of my invention to the
described movement of the pressure plate arm‘ modi?cation shown in Fig. 4. In the structure’
attendant mechanism until frictional contact is shown in Figs. 1 and 2 it will be understood that
reached between the pressure plate or plates and the driving load is normally taken through both
20 the driven disc. When this contact is ‘reached faces of the driven clutch plate, substantially half 20
the drag between the pressure plate and flywheel the load being transmitted through the face M
and the driven disc opposes further engagement
‘of the clutch and tends to reduce the speed of
the driving member. Meanwhile torque is trans
mitted which tends to bring the driven member
up to the speed of the driving member. If the
load to be transmitted is light, relatively little
centrifugal force need be developed to establish
engagement because the tendency of the clutch
to release itself is correspondingly slight. Where
a high torque is required to start the driven mem
ber, greater speed must be developed in the driv
ing member during the period of initial slip.
It will thus be seen that the engaging pressure
35 developed in the clutch, at least in its initial
engagement is measured by the load to be trans
mitted. By this relationship, one operating the
clutch is assured against grabbing because the
very tendency to grab asserts itself by opposing
‘fill and reducing the effective engaging pressure, and
is further assured against grabbing by the tend
ency of the clutch to engage rapidly only when
the load is proportionately light, and by the tend
ency of the clutch to resist engagement when the
load is high until such time as the speed of the
‘driving member has gradually become su?cient
while overcoming the resistance of the clutch to
engage, to carry smoothly the greater load which
it undertakes to transmit.
After initial engagement has been effected and
during low rotational speeds the governor weights
are preferably proportioned to respond to torque
overloads by being moved inwardly about their
pivots Si by the relative negative rotation be
65 tween the pressure plate and the housing 2, thus
permitting slippage and dissipation of the over
load. When the overload has passed, the weights
will again swing outwardly to a position deter
mined by the speed of rotation. During high ro
till tational speeds the governor weights are prefer
ably proportioned to be held in their outermost
position by the higher centrifugal force, and
torque overloads may compress or collapse the
springs 33 without effecting any movement of
the governor weights; thus also permitting‘ slip
page and dissipation of the overload. Theoreti»
cally a condition may also exist where the over-V
load force tending to collapse the springs and
move the weights inwardly does ‘both things more
or less at about the same time with substantially
and the other half through the face IS; the face
135, bearing directly against the ?ywheel, nor
mally continuing in static frictional engagement
therewith until this engagement is broken by an 25
overload which is made up at least in part of the
transfer of load from the rear face it to the
front face l5 when the release is initiated by cir
cumferentiai and axial motion of the pressure
plate ll'with respect to the ?ywheel. I contem 30
plate that the mechanism shown in Fig. 4 will be
more sensitivein respect to overload slippage and
more smooth in its engagement and more adapt
able for use with a wider range of friction mate
rials, because I have incorporated in that struc 35
ture an auxiliary pressure plate or ring 6A, which
functions with respect to the forward face ill
of the friction plate in the same way that the
pressure plate it functions with respect to the
rearward face i of the friction plate; the plate 40
or ring?lA having a frictionless or relatively low
frictional engagement with the ?ywheel as such.
By securing the plates 55 and 4A together with re- '
spect to ‘circumferential movement, all of the
transmitted torque or load is ultimately trans 45
mitted through the pressure plate 43, thence
through the springs 33 and the centrifugal gov
ernor mechanism. Thus because the auxiliary
pressure plate the has only a small or negligible
friction relationship with the ?ywheel, the whole 50
oi’ the effect to be established by the engaging
and releasing mechanism is applied equally and
in the same way on both the front and bacl: sides
of the driven friction disc.
The clutch assembly of Fig. 4 may be referred 55
to as a double plate assembly in that the second
preset re plate 41A is provided to engage the for
ward face it of the clutch disc. The pressure
plate 5A comprises an annular ring mounted for
rotary movement within an annular recess in 60
the rear radial wall of the flywheel. A bearing
ring 3A is carried by the ?ywheel within said
recess and may be formed of graphite bronze or
like material having a low co-e?lcient of fric
tion to insure relatively free rotary movement of 65
the pressure plate GA with respect to the fly
wheel. A plurality of pins dB carried by the
pressure plate It extend forwardly therefrom and
have a free sliding ?t within a like plurality of 70
the same result, namely slippage, mentioned I holes in the pressure plate 5A. A series of leaf
Since the clutch disc friction face 35 bears
' against the ?ywheel l in this form of my inven
tiou, the drive is equally vdivided between the
springs 55% may be applied to the forward face
of the pressure plate 6 beyond the perimeter of
the clutch disc in a position to engage the pres
sure plate tato prevent a‘ "freezing" of the 75
pressure plates to the clutch disc‘ as heretofore
urge the-pawls into engagement with
the ratchet ring 80.
. The double plate construction results in a si-v ' ~When it is desired to start the prime mover
multaneous rotary movement of both pressure - of the motor vehicle by this means, a rotation
of the shaft l8 may be e?’ected through a geared
plates within the clutch mechanism and a main
engagement of‘ same to the rear wheels of ‘the
tenance of the same friction bond at both fric
tion faces M and I5 of the clutch disc during
such movement. The frictional drive through
vehicle and through the pawl and ratchet til-8i
rotate the ?ywheel. The springs 83 and pawls
ti vare so balanced with respect to each other
that the centrifugal force attending ?ywheel ro 10
tation will throw the pawls out of engagement
faces is more evenly proportioned.
Itmay be found advantageous in connection with the ratchet ring 80 ‘and compress the‘
springs 83. Thepawls will be maintained out of
with a clutch constructed according- to the pre
' cents of my invention to provide a manual re-’ ‘ engagement with the ratchet ring by centrifugal
force while the motor is running but will be re 15
vll'i lease of the clutch and Figs. 8 and 9 illustrate
a modi?ed clutch assembly suiteddfor manual turned to their operative position as soon as the
release. The clutch casing 2A in this instance is ' motor stops. The motor driving counterclock
radially ?anged at 6 on its outerperiphery for wise as seen in Fig.'l1 drives the pawls to over- '
attachment to the ?ywheel and‘ formed at 5 run the ratchet in any event.
my 20
manually operated throw-out mechanism. The invention into practice more readily, I will set
radially outer-wall of the casing 2A is slotted forth in the following paragraph, reference be
aslat ‘I to afford a splined engagement with an ing made to the embodiment of Figures 1, 2, and
inner casing 3 mounted for axial movement 3 particularly, an example ,of the mathematical
which I have found ‘successfully oper 25
at within the main casing 2A. The casing 3 sup values
ports therein the governor weights and pressure ative for such selectively variable factors as the
inclination of the cam faces lii—t2 and the
plate‘ actuating mechanism as heretofore de
scribed in connection with the description of the weight ol-the- governors 30 and the like.
the clutch disc is thus equally distributed as to
time and amount and the wear‘ on the frictio
‘embodiment shown in Figs. 1, 2 and 3.
The inner ?ange 5 of the casing 2A is slotted
at equally spaced intervals as at 24 adjacent the
axial wall of the casing to provide a free sliding
?t for clutch throw-out hook members 26. Each
hook member 26 is provided at its forward end
35 with an outwardly disposed hook 25 adapted tov
engage a ?anged rim 9 of the inner casing 3.
The ?ange dot the main clutch casing 2A is
formed with a raised rib‘ 23 adjacent each of
the slots 24 that constitute fulcrums for clutch
40 throw-out levers ii. The inner ends of said
levers 2i are arranged to engage a throw-out
bearing 20 carried by the driven shaft Ill and
the outer ends _of the levers 2i engage inwardly
turned hooks 222 of the hook members 28. A
45 forward movement of the clutch throw-out hear
ing 20 will cause the levers 2i to turn about ful
crums 23 and vpull the hook members 2b and
inner casing 3 rearwardly within the outer or
m‘ain casing 2A. The movement of the throw
50 out bearing may be e?ected by a yoke and foot
pedal arrangement as will be understood by
In a current model of motor vehicle weighing
approximately 2600 pounds, with a motor devel
R. P. M. and about 90 brake horse power at‘
3750 R. P. M., I_ have satisfactorily operated a
clutch constructed according to the precepts of
my invention described herein. In this clutch 35
each ‘governor weight to weighed about one
pound and was pivoted to effect about a 2 to 1
reduction from the center oi’ mass of the governor
‘weight to the point of application to the pins M
in the pressureplate. The pins M were disposed 40
about four inches from'the axis of the clutch,
which also is roughly the radius of the center of
mass of the governor weights, and in this par- .>
ticular instance I used springs 33 which required
about 225 pounds pressure to bottom the strands 45
- upon'each other, and which exerted about 180
pounds when compressed to within about 3% of
an inch ‘from bottom.- With these springs ini
tially compressed at about lull pounds, an over
load or sheet: of less than 40 foot pounds was
required to slip the clutch at and above rota
tional speeds where the governor weights resisted
an inward movement before slippage was ef
those skilled in the art. To hold the inner oas
ing 3 forward in its normal operative position a
series of perimetrically spaced leaf springs ll are i’ected by compression of the springs. The cam
faces hi and M were inclined at about 20 degrees
55 preferably interposed between the two casings. with respect to the radial plane of the pressure
The operation of the‘ clutch provided with a
plate. The 'pressureplate and clutch disc had
manual release is substantially as heretofore de
scribed in connection with the description of the a coemcient of dynamic friction of about .3 anda
embodiment of Figure l or the double pressure _ coefficient oi’ static friction of about .35.
To further illustrate the principles involved in
plate arrangement of Figure. 4 and it is to be
operation of my clutch and using by way of
understood that the manual clutch throw-out
mechanism may be applied‘ to either of said example the particular values given above, let
us assume-that the automobile is being operated
In the event that the clutch of my invention j under a condition where the engine speed is about
2300 R. P. M., and is developing about its mam
65 is applied to an automotive vehicle ‘and it is
desired to start the engineof the vehicle through mum torque of 151 foot pounds at that speed.
the medium of the driven shaft, Ihave shown We will also sume for the purpose of this ex
in Figs. 10 and 11 a mechanism to accomplish ample that th driving and driven members are
this function. ‘A ratchet ring 85 is applied to initially rotating in vsynchronism, i. e. that the
clutch is fully engaged. At this speed each gov
‘the hub ill of the clutch disc and may be se
emor weight M is swung outwardly by centrifugal
cured thereto by the rivets l3‘ employed to at
tach the clutch disc to the hub. Adjacent the force which roughly equals 0003410 WRNQ, i. e.
periphery of said ratchet ring and pivotally _ about 609 pounds,'__,;W being the mass of each
mounted on the ?ywheel are a group of spring
pressed'pawls ill. Thesprings 83 carried by the
oping about 151 foot pounds torque at 2300
weight in pounds?-RQI the radius of rotation in
feet, and N the number of revolutions per minute.‘
f is
2,129,218 '
In the clutch ‘shown in Figs. 1, 2, and 3, having
pressure developed across each pair of cams 5!, 52 '
a single pressure plate to which this example
of about .273 pounds, which would require an
relates, about half the torque will be delivered
through the ?y wheel to the driven disk, and the
additional circumferential pressure from the
governors through the springs 33 and pins 45
other half will be delivered through the pressure onto the pressure plate of about 99.5 pounds,
plate to the driven disk. ‘Thus in transmitting which added to the 95.5.pounds torque pressure
151 foot pounds torque about ‘751/2 foot pounds would demand a total of 195 pounds, 1. e. a pres
will be transmitted through the pressure plate .sure 15 pounds in excess of that which would
by way of the springs 33,- cams and governors to cause compression of the springs 33, and would
10 the driven disc. Since the pins 665 are about four therefore’ tend to permit the clutch to slip until
inches or a third of a foot from the axis of the the overload had been dissipated, or until the
clutch, and since there are three pins at through condition of overload had ceased to exist.
which this torque is transmitted, each pin will
In a single plate clutch as shown in Figs. 1, 2
have a torque load of about 751/2 pounds.
and 3, the substance of the foregoing calculations
is To carry the gross torque load of 151 foot can be expressed in the following formula:
pounds, it is obviously necessary that the pres
sure plate exert an axial pressure toward the
fly wheel su?icient to, maintain clutch engage
ment depending upon the coeflicient of static
20 friction of the friction material. In this example
the coe?lcient'of friction being .35 and there
being two friction surfaces, and vassuming the
it will be seen that the gross pressure exerted by
the pressure plate must equal the torque in foot
pounds multiplied by 3 (to give the pounds drag
on a four inch radius, i. e. 453 pounds) and that
amount vmust be divided by two times the co
30 e?lcient of friction, which will equal about 647
cumferentially from the weights either through
springs, 33 orother means to the pins 418, assum
In the clutch; according to this example, this
64f? pounds is developed across the three inclined
cam surfaces 5!,52 and since these surfacesare
35 inclined at about 20°, the circumferential pres
sure which must be applied to the pressure plate
on the pins dd whereby to obtain an axial re
action to develop the above mentioned pressure »
at each of the pins dd, must equal the gross
40 pressure, 647 pounds, divided by 3 (the number
of pairs of cams) and multiplied by the tangent
of 20°, which results in about 78.3 pounds pres
sure, which must also be delivered to each of
the pins M by the governor weights to main
45 tain the engagement under the condition herein
As we have seen, the governor must transmit
about 75.5 pounds to the pins $6 in opposition
to the transmitted torque, and must also deliver
50' to the pins dd about 78.3 pounds to’ maintain
the pressure on the pressure plate.
Thus under
the conditions stated the governor must deliver
to each of the pins M a. gross pressure of about
153.8 pounds to maintain the clutch engagement
and transmit 151 foot pounds‘torque. As above
indicated, I preferred in this particular clutch
to use springs initially compressed'to about 180
pounds, so that under the conditions stated the
springs would not havebeen compressed beyond
60 their initial compression to transmit the maxi
mum torque of this particular engine. It will
be seen from the above ?gures, however, that a
determinable torque overload or shock will cause
the clutch to slip to dissipate the shock and pro
65 tect the attendant mechanism.
If an overload of 40 foot pounds of torque were
thrust upon the clutch, raising the total torque
momentarily sought to be transmitted from 151
foot pounds to 191 foot pounds, then each of the
70 pins lid would tend to have thrust upon it about
95% pounds direct torque load. The drag in
pounds on the four inch mean effective radius
of the clutch would be increased to about 5'13
pounds, which would require a pressure on the
pressure plate of about 820 pounds or an axial
delivered by the pressure plate in the direction
of the fly wheel friction face to bind the driven 20
member for any given coe?icient of friction on
any number of friction surfaces; C is the tangent
of the angle of the cams El, 52‘ with respect to
the radial plane of the pressure plate; T is the
torque load measured'in pounds at the mean 25'
effective radius of the clutch face or faces; and
where F is the force in pounds transmitted cir
mean effective radius of the friction surfaces to
be about four inches from the axis of the clutch,
where A is the axial pressure which must be
ing that the pins 34 are at the same radius as 30
the mean e?ective radius of the clutch faces.
In. the modi?cation shown in Figure 4 where
two pressure plates are employed, 1. e. one on each
side of the driven disc, and where all or sub
stantially all of‘ the torque from both sides of 35
the driven disc is transmitted through the pins
54 onto the govemor, then the above formula
will read:—
From the foregoing calculations and formula
it' will also be seen that whenever the clutch is
caused to slip by a shockv or overload, and par
ticularly in instances where the coe?icient of
dynamic friction is less than the coefficient of 45
static friction, that immediately upon slippage
a lesser torque load is imposed on pins 44 which
permits a greater portion of the governor de
livered pressure to be available through the cams
51, 52 for effecting axial pressure upon the pres 50
sure plate.
In effect, this means that the con
dition of slippage tends to be self-eliminative as
soon as the condition‘of overload has ceased to
exist. It will also be understood that a condi
tion of slippage necessarily implies a speed dif 55
ference between the driving and driven member,
wherehy the kinetic energy ofthe driving mem
ber and driving means, as measured by this
differential in speed, is available to tend to bring
the driving and driven members into a state of 60
synchronous rotation, when the condition of over
load has ceased to exist. For these reasons it
will also be appreciated that the clutch, while
engaging, that is while changing from a condi
tion of slippage to a condition of synchronous 65
rotation between the driving and driven members,
will do‘ so very smoothly and without shock or
jar because every tendency which might result
in a shock or overload would of itself also tend to
continue or begin anew a condition of slippage, 70
while transmitting substantially continuous torque
for any given condition of speed and load, from
the driving to the driven member and always
tending to bring the driven’member up to the
speed of the driving member.
1 In starting the clutch, discussed herein by way and t will equal .825a. Knowing, as above stated, ;
of example of the single pressure plate type, one. that a+t=24 at‘600 R. P. M., then it can be de
termined that t will equal 10.83 pounds'and a will
?nds from the formula noted above for centri
fugal force, (disregarding for the. sake-£3 easy equal 13.17 pounds. Thus T will equal (it-{or 65.04
pounds at a four inch- radius, which equals,21.66
calculation the change in the radius of the cen
ter of mass of weights) that each of the weights foot pounds torque. Thus we learn that‘ at_600‘ -
develops‘ about 28 pounds centrifugal forceat
about 500 R. P. M., and about 49 pounds ycen=
R. P. M., while the- clutch is slipping, it will - ,
potentially transmit 21.66 foot pounds torque.
When in .the automobile in which my clutch
trifugal force at about 608 R, P. M. It will thus .
may be installed, the above amount of torque
10 be seen that by stressing the governor weight re
is su?icient to start the car along the surface;
tractor-springs 62 to about 28 pounds when the
weights are in their innermost position, as shown
in Fig. 2, there will be nooutward movement of
the weights due to centrifugal force at any speed
15 less than 500 RP. M. By selecting or adjusting
the springs 42 to various tensions the speed, when
the weights may ‘begin their outward movement,
can readily be determined.- _
Assuming, however, that the springs 182 each
20 exert an initial‘ retracting action on the weights
of about 28 pounds, it will be seen that when the
engine or driving member is rotating at 600 R. P.
upon which it has been standing, and if the en
gine speed‘ were maintained substantially com
stant, then a smaller amount of torque would be }
required to move the car at an even pace than
would be required to start it; hence the value ‘
of t would become less as the car approached. ‘
a constant speed, and the value of a would be
come greater with the result that greater engag
ing pressures would be developed in the clutch
to bring the driving and driven members into
synchronism. Whensynchronism was obtained,
there wouldalso be a change from the dynamic
centrifugal force of 12 pounds acting radially out- ’ to the static coe?icient. of friction, which would I
modify the formula t=.825a to read t=.962a,:
25 ward in each weight, which when translated in
and thereafter the maximum value of t for that a
. to a circumferential force with a mechanical ad
vantage of about 2 to 1 will make available speed and condition would be 11.77 pounds, and
the gross torque then potentially transmittable
about 24, pounds to be transmitted circumferen
tially from each ‘of the weights to each of the at that speed would be about 23.54 foot pounds.
30 pins 46, i. e. to the pressure ‘plate. As noted If a‘ torque load of any greater ‘amount were
on the clutch at this speed, slippage
above this force, which we may for convenience ‘ imposed
by virtue of the pretsure plate mov
designate f, as measured from each weight, is
ing counterclockwise as viewed in Fig. 2 and
available at each of the pins It to move the pres
sure plate both circumferentially and axially as - moving the weights inwardly against the resist
determined by the cams M, .52. As has also been ance of centrifugal force. While the clutch is
M., there will be a resultant available operating
slipping at this speed it will continue to transmit
21.66 foot pounds as above, shown.
slippage due to overloads will be accomplished
pressure upon the pressure plate, and another '
the same manner in the clutch having the
part, which I designate It, will be available to speci?c
values herein given at all speeds less than 40
40 oppose that portion of the torque which is trans D about 1100 R. P. M. At higher speeds overload
mitted through each of the pins M onto the slippage will be accomplished essentially by com
governor mechanism.
‘At 600 R. P.'lVI. the force I of 24 pounds will pression of the springs 33, if that be desired, in
manner above shown.
equal a plus t, and if it be desired to know what the
From the foregoing example of speci?c values
torque can be transmitted'through the clutch
for governor weights and the like, which have
at‘ this speed, the following calculations can be been
given to more fully illustrate a speci?c
operative structure built in accordance with the
The formula heretofore given being,
precepts of my invention, it will be understood
demonstrated above, part of the force j, which
I designate a, will be devoted to exerting axial
~ '_A
that some or all of the values given may be varied 50
and the exemplary clutch having three pins, 20°
cams, two friction surfaces, and a coemcient of
within reasonably wide limits without departing
from the teaching of this speci?cation. and that
the values given above are given. for the purpose
dynamic friction of .3, then the value of ‘T in of illustration and example. It will also be un
derstood that the calculations above given have 55
the above formula will equal 2 (the number of fric
tion surfaces) times 3 (the number of pins or been illustrative rather than precisely accurate,
governor weights) times t (the torque in pounds ‘such well known phenomena as the stress strain ,
delivered through each of the pins ltd upon each characteristics of the springs being disregarded
_ ’
of the governor weights). It will also be seen for the sake of brevity.
It will be understood from the foregoing de 60
scription that the governor weights it, the springs
‘ ber of pairs of cams or pins or governor weights)
33, if any, the inclination of the cams iii-52, the
divided by .364 (the tangent of the angle of in
clination of the cams) all multiplied by a (the coemcient of friction between the clutch‘ sur
force\delivered by each Gill-{he governor weights faces, the character of the retractor springs 652,
which is consumedin urging the pressure plate
. into engagement with the driven disc).
Where the coemcient of dynamic friction is .3
. and where ‘the clutch has two friction surfaces, '1'
will equal 5A, and since T equals 6t and A
then 61? will equal
acteristics of the clutch.
Thus it will be observed that the springs 33
might be replaced by solid members 33a as in
Figure ea or that the weights 30 might be pro- ,
vided with integrally formed members 33b ar
ranged to directly engage the pressure plate pins
and other elements are all factors which affect e.
‘ each other and contribute to the operating char
tit as shown in Figure 9b. This would result in a
clutch responsive by slippage under overloads at
low rotational speeds by moving‘ the governor 76
weights inward but transmitting all torque up
to thee?ective centrifugal force of the weights at
all engine speeds. Since centrifugal force in
creases as the square of the speed, such a clutch
would be substantially non-slippable at high en
gine speeds, if reasonably slippable at low engine
speeds. I contemplate however that this ‘char-_
' acteristic might be advantageous under some
While I have illustrated and described a pre
ferred form of my invention, shown certain
specific modi?cations thereof, and given illustra
tive examples of a practical embodiment thereof,
numerous and various modi?cations and changes
15 will occur to those skilled in the art all within
the spirit and precepts of my invention, and I
whereby the torque transmitted from the driving 10
member through said‘ plates to the driven mem
ber tends to release the clutch, and means for
permitting the release thereof effective to permit
slippage between the pressure plates and the
driven member in response to relatively light 15
overloads at higher speeds.
6. In a clutch,’ a driving member, a driven
forms of my invention herein illustrated and
described or limited in any manner other than
member, a pressure plate operatively associated
29 by the claims appended hereto when construed
with the range of equivalents to which they are
with the driving member and frictionally engage 20
able with the driven member, said plate being
circumferentially and axially movable with re
I claim:-—
into axial movement with respect to said driving
member for engagement or disengagement with
said driven member, means for moving said. plates
circumferentially in the same direction as the di
rection of rotation of the driving member against
the resistance of the driven member for exerting
engaging pressure upon said driven member
overloads at low.speeds and relatively/‘greater
do not care to be limited to the precise form or
respect to said driving member, means for trans
lating circumferential movement of said plates ,
spect to said driving member, means for trans- .
, 1. In a clutch, a driving 'member, a movable
lating circumferential movement of said plate
25 pressure plate associated therewith, a. driven
into axial movement with respect to said driving ‘
member frictionally engageable with said pressure
member for engagement with saiddriven member.
means for moving said plate clrcumferentially in
plate, means ' interposed between said driving
"member and ‘said pressure plate and reacting
the same direction as the direction of rotation
therebetween for translating relative circumferl
of the driving member against the resistance of
the driven ‘member for exerting engaging pressure 30
upon‘ said driven member whereby the torque
30 ential movement between said member and said
plate into axial movement toward or away from
said driven member, and means positively respon
sive to speed and negatively responsive to load
transmitted from the driving member through
for moving said plate with respect to said mem- ’ said plate to'the driven member tends torelease'
the clutch, and means for permitting the release
35 bers.
thereof e?ective to permit slippage between the
2. In a‘clutch, a driving-member, a movable" pressure
plate and- vthe driven member in' response
to relatively light overloads at low speeds and
member frictionally engageable with said pres
relatively greater overloads at higher speeds.
pressure plate associated therewith, a driven
sure plate, and means interposed between said
40 driving member and said pressure plate and ro
'7. In a clutch,~a driving member, a driven
member, pressure plates operatively associated 40'
with the driving member and frictionally en
gageable with the driven member, said plates
being circumferentially and axially movable with
tatable therewith and reacting therebetween in
positive response to speedand negative response
to load to move said plate into engagement with
said driven member, said 'means comprising a
respect to said driving member, means for trans
lating circumferential movement of said plates
into axial movement with respect to said driving
centrifugal governor having a limited movement
and resilient means for transmitting the governor
actuating force between said plate and said
member for engagement with said driven mem
ber, and meansformoving said plates rotational- _
ly in the same direction as the direction of rota
3. A clutch including driving and driven mem
68 bers, means carried by the driving member and
arranged between said driving and driven mem
tion of the driving member against the resistance
of the driven member'for exerting engaging pres
sures upon said driven member whereby the
torque transmitted from the driving member
bers for limited rotation relative to said driving
,member, said driven member tending to effect
said relative rotation in a‘ direction opposite to
55 the directional rotation of the driving member,
and centrifugal force responsive means tending
to effect said relative rotation in the same direc
tion as the directional rotation of the driving
s. A clutch including driving and driven mem
bers and having clutch elements arranged for
frictionally interconnecting said members, means
to vary said frictional engagement, said means
comprising a pair of spring connected movable
mechanisms, said mechanisms moving jointly in
one direction to increase said frictional engaging
pressures in response to increases in rotational
speed and being independently movable in an op
posite direction to decrease said frictional engag
70 ing pressures in response to increases in torque.
5. In a-clutch, a driving member, a driven
member, pressure‘ plates operatively associated
with the driving member and frictionally en
gageable withv the driven member, saidplates
75 being circumferentially and axially movable with
through said plates to the vdriven member tends
to release the clutch.
8.1m a clutch, a driving member, a driven
member, a pressure plate operatively associated
with said driving member and movable circum
ferentially and axially with respect thereto into
engagement with. said driven member, means
interposed between the driving member and said
plate for translating relative rotative movement
into axial movement therebetween, centrifugally
actuated means tending to urge said plate in the
direction of rotation of the driving member and
into engagement with the driven member, re
silient means interposed between said centrifugal
means and said plate, and means to limit the
movement of said centrifugal means whereby the
force required to cause the clutch to slip does not 70
increase with the speed of rotation beyond the
point where the limit of- movement of said cen
trifugal means is reached.
9. In a clutch, a driving member, a driven
member, a pressure plate associated with said id.
driving member and axially movable into fric
tional engagement with said driven member, re
silient means for driving said pressure plate from
said driving member, speed responsive means act
ing through said resilient means for rotating said '
pressure plate with respect to said driving mem
ber, and load responsive means for translating '
therebetween for translating relative circumfer
cntial‘movement between said member and said
plate into axial movement toward or away from
said driven member, and means positively respon
sive to speed and negatively responsive to load :1
for moving said plate with respect to said mem
ber, said last named means including anti-fric
tion means to facilitate the transmission of said
said rotational movement of said pressure 'plate, positive and negative forces to said plate.
with respect to said driving member into axial
13. In a clutch, a vdriving member, a driven
movement of said pressure plate.
member, means associated with one of said mem
10. In a clutch, a driving member, a driven
member, means associated with one of said mem-,
bers adapted to engage the other of said members,
speed responsive means tending to establish such
15 engagement and load responsive means tending
to establish disengagement, said ?rst vnamed
means including a pressure plate having an anti
iriction support in said clutch for free movement
under the in?uence of said speed and load re
20 sponsive means.
11. In a clutch, a driving member, a driven
member, means operatively associated with one
‘ of said members adapted to frictionally engage
the other of said members and means positively
25 responsive to speed and negativelyv responsive to
load acting between one of said members and said
?rst named means for e?ecting ‘frictional engage
ment of said members, said last named means in
cluding anti-friction means to facilitate the
30 transmission of said positive and negative forces
to said, ?rst named means. f
12. In a clutch, a driving member, a movable
pressure plate associated therewith, a driven
member frictionally engageable with said pres
35 sure plate, means interposed between said driv
ing member and said pressure plate andreacting
bers adapted to engage the other of said mem
bers, speed responsive means tending to estab
lish such engagement and load responsive means
tending to establish disengagement, said first
named means including a pressure plate having
an anti-friction support in said clutch for free
movement under the influence of said speed and
load responsive means, said anti-friction support
comprising round anti-friction devices arranged‘
between opposed inclined surfaces.
14. In a clutch, a driving member, a driven
member, means associated with one of said mem
bers adapted to engage the other of said members,
s‘peed responsive means tending toestablish such 25
engagement and load responsive means tending
to establish diengagement, said ?rst named means
including a pressure plate having an anti—fric
tion support in said clutch comprising anti-fric
tion devices arranged between opposed surfaces
which are inclined with respect to said plate at a
nonself-sustaining angle whereby. the pressure
plate is freely movable under the in?uence of
said speed and load responsive means.
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