US2677946A - Coupling - Google Patents

Description

May 1l, 1954 COUPLING R. M. PURDY 2,677,946

Filed May 3, 1950 1N VHV TOR.

4942A, d. [im

ATTORNEY.

Patented May l1, 1954 ACOUPLING: Rolland -M. Purdy,'Bainb1-idge, N. Y., assignor -to `Bendix Aviation 'orporatiom New York, -N. .Y

:a corporation .ofhelawalfe Application aMay 3, 1950, SerialNo. 159,773

v11 fClaims.

This `invention relate to couplings and 'more particularly to apparatus for drivably Aconnecting 'rotatable parts While permitting `andantematically controlling limited relative `angular movement of vsaid parts.

Among the Amany'uses of this invention "is-its particular application to the timing of sparks produced by the ignition system of a combustion engine or the like, and 'the invention will be i particularly described inconnection with a-mechanism-suited'to thatuse. It is to be `understood however, that this particular 4description is for the purpose of'illustration 'only and "does not constitute a limitation upon "the natural 'scope :of the invention.

One of the objects V`of `the present invention is to provide novel coupling means for connecting rotating-parts,whichmeans are adapted to effe-ct relative angular movement 'of said l'parts 'in response to or in accordance with variations inthe speedof rotation of 4said parts.

Another obj-ect of vthe invention is ito provide a novelly constructed lcoupling device 'which dis adapted, by way of example, `rto automatically advance or retard the sparks ofan Iinternal 4combustion Vengine when -a particular speed 'of 'rotation is reached and to automatically :further advance or retard the `spark when 'a "different increased speed of rotation is reached.

Still another -ob'ject is to provide a coupling Aof the type which is actuated'by centrifugal force to effect relative angular movement 'of driving and driven parts, said coupling being novellyc'onstructed so as to reduce friction and 'the e'iTects thereof to a minimum.

A further object of fthe -invention to couple driving and driven members lbyeJ `novelrcoup'ling; that automatically changes the angular relationship of said members at particular speeds-of rotation or during particular ranges of increasing or decreasing speeds.

Still another object is-to provide Va speed sensitive coupling between rotating parts, "the sensitivity of which can be varied in a novel manner to vmake it operate in accordance with predetermined requirements at different speeds.

Another object is Vto provide .novel means to control the movement cfa centrifugal weight, and a fur-ther object nis to obtain 'such control by novel means for changing thevleverage "or mode of operation of 'a vcontrolling vdevice with respect to the weight.

-A still further vobject lis to `provide means for simultaneously and equally r`adjusting fthe control 'means for =a plurality 'of 'centrifugal Weights 2 in novel combination withvnovel `means `for ad- Vjusting lthe control means for each weight to -vary-the operation'thereof in response to `variations in speed.

The above landfurther objects and novel 'features of the invention will more Vfully appear from 'the following detail description when the same tis read in `connection With'the .accompanying drawings. 'It is Ato be Aexpressly understood, however, that the drawings are for the purpose of 'illustration 4only and `are 'not intended fas a definition of the limits 'of the invention.

In the drawings, -wherein like reference characters referto like parts 'throughout "the several views,

Fig. 1 is a lvert'icalfsection of one form of device exemplifying nthelinvention, the section being ltaken substantially on line 'l-l Aof`Fig.`2

`vFig. '2 is a vertical section on Vvthe `line `2`2 of Fig. 1, looking in the direction of the arrows, `the -cover lplate having 'been removed to expose the centrifugal -ywei-ghts;

Fig. 3 is a Yvertical'section on the line 3-3 oi" IFig. f1, looking lin the direction 'of the arrows, the cover `plate having been removed to `expose the yweights;

Fig. 4a is an end View of `a heavy `flyweight, and Fig. 4b is-an lend view of alight iiyweig'ht, `the weights being'arranged to show a size rela.- tion that may sometimes be employed;

Fig, 5 is adetail View, partly 'in section, taken online 5 5 of 'Fig'. 2;

Fig. '-6 isa rvdetail view, partly in section and with parts broken away, taken substantially on line 6A- 6 of Fig. 2; and,

Fig. `'7 is -a ldiagram graphically illustrating one typical mode of operation of a device of the type shown in Fig. l.

In some environments iinternalconibustion engines are desirably operated at certain speeds with an advanced spark vand at other speeds with a retarded spark. In the case 'of automobile engines, the advance and retardation of the spark were originally accomplished -by Vvmanual means, but more recently Lby automatic means. In aircraft engines, `it is also :desirable during differ- .ent .phases .of operation, such as in starting, taking off, idling, cruising, full power, etc., to operate with an advanced nr a :retarded spark, as the circumstances demand.

The invention provides :the

such engines with novel :speed .sensitive imechspark when selected :engine l.speed-.s have been reached and contemplates for this purpose novel senese means for altering the angular relation of driving and driven rotating members. The invention also provides control of the rate at which this angular adjustment takes place between predetermined speeds. In the drawings, a rotatable member, such as the shaft of a magneto, timer, distributor or the like of an ingition system, is indicated by the numeral I0. Upon this shaft is a driving gear I I, a driven gear I2 and a rotary support I3 between them. Double ended bearing pins I4 are mounted in the support andioarry gear segments I5 that are in mesh with the gear II and gear segments I6 that are in mesh with the gear I2. The gear segments I5 extend beyond the points of pivotal attachment to the pins III and form centrifugal flyweights Il (Fig. 4a) that are of a relatively heavy construction. Gear segments I6 extend beyond the pins on which they are pivoted as centrifugal weights IB, which in the mechanism illustrated, are of relatively light construction, as illustrated in Fig.` lib. Annular cover plates 35 and 36 are mounted on hollow pins III by means of bolts 31 threaded into said pins and serving to retain the iiyweights on the pins.

The engine drive (not shown) meshes with the splines or gear teeth I9 of gear member II and rotates the latter clockwise rotation as viewed in Fig. 2 being assumed for purposes of this description. The rotative effort of the gear member II against the gear segments I5 urges flyweights I1 centripetally and forms in effect a positive driving connection that rotates the pins I4, support I3, gear segments I3, gear member l2, and the shaft I as a unit, the latter .and gear member III being drivably connected by splines 23. However, when the speed of rotation Vhas increased suciently the fiyweights Il move centrifugally under the impulse of centrifugal force, the gear segments I walk about the gear II, angularly advancing the support I3 and all the mechanical connections that follow it, and imparting an angular advance in the direction of rotation to the driven gear I2 and to the circuit breaker cam or other mechanical device loperated. thereby. It may be here pointed out that the invention may be incorporated in a device embodying a single flyweight or a single set of iiyweights, such as flyweights I1, in Which case the support I3 may be considered as the driven member.

After yweights I1 have functioned as described above to vary the angular relationship of the driving and driven parts, upon a further increase in the speed of rotation the flyweights I8 are actuated by centrifugal force to apply through gearsegments IE and gear member' I2 a retrograde relative angular motion whereby a reverse adjustment of gear I2 and shaft I0 with respect to gear II will take place and the spark will be retarded. It will be understood that this relative angular adjustment can be availed of in either direction With this coupling, depending upon which is the driving and which is the driven gear or upon the direction of rotation.

p Referring now to the novel construction of the embodiment of the invention that is illustrated in the drawings, I0 indicates, generally, a shaft of an instrument, such as a magneto or ignition timer, having an abutment formed on the shaft as a thrust collar or bearing for the inner race of a roller bearing v2| that carries the'bearing area 22 of the shaft I0. To the left of said abutment and the bearing area as viewed in Fig. 1, the shaft I0 is provided with splined portion 23 and a reduced smooth portion 24 that is screw threaded at its end for the reception of a nut 25.

The gear member I2 is mounted on shaft III by intertting internal splines that mesh with the splines 23 and is provided with external gear teeth adapted to mesh with gear segments I6. A washer or spacer 21 ts over the reduced portion 24 of shaft I0 and is brought up against a shoulder formed inside gear member I2. A bearing and spacing sleeve 28 is placed over the end 24 of the shaft and brought up against the washer 2l. The hub 29 of the annular support I3 is freely mounted upon the inner end of the sleeve 28 so that a portion of the hub fits within the gear I2 and bears against washer 2i. The gear II is freely mounted on the sleeve 2B with an inner annular flange circumscribing the hub 29. The parts of the mechanism above described are held in assembled relation by means of a thrust Washer 35, a lock washer and, the nut 25. The central portions 3| of pins I4 are larger than the bearing portions at the ends thereof and are preferably mounted fixedly on a single diameter of the support I3 in order that the parts of the apparatus may be in dynamic balance. The enlarged central portions 3i of pins III project slightly beyond the faces of the support and constitute abutments that, together with the sleeve. 23, provide clearance for the parts of the assembly. The gear segments I5, I6 and the iiyweights are spaced from support I3 by the projecting parts of the enlarged portions 3| of the pins. Because of their intertting splines the gear I2 must rotate with the shaft I0 and because of the connection of the gears II and l2 with the support I3 through the medium of gear segments I5 and I3 and pins I4, the parts of the mechanism will rotate as a unit despite the revolvable mounting of gear II and support I3 on sleeve 28.

The invention contemplates novel means for controlling the movements of the centrifugal flyweights whereby the coupling may be readily and easily adjusted to function at different speeds and during selected speed ranges to effect desired relative angular movements of the driving and driven members of the coupling. Said means are suchas to permit adjustment of the coupling to vary the speed or speeds at which such relative movements are initiated as well as to. vary the rate at which such relative angular movements occur, said rate being shown by the `slope of thecurve representing the angular relationship of the rotatable parts plotted against speed of rotation (Fig. 7). The novel control means provided is such that the effects of friction are reduced to a minimum so that the abovementioned curve of operation for increasing speeds will be retraced as nearly as possible when the` speed of rotation decreases. In the form shown, the control means for each iiyweight is of rthe same construction so that a description of one will suffice.

, ,Mounted at the circumference of and piloted for angulary adjustment on the support I3 are abutment rings 40 and 4I on which leaf springs 42 are riveted, bolted or otherwise suitably fixedly or adjustably secured. operatively interposed between the free end of spring 42 and a centrifugal weight I1 or I8 is a link 50, which as shown is in the form of a rectangular-like frame (Fig. 5). The outer or upper cross bar 5I of. said link .makes a fulcrum or pivotal engagement with a notch or recess 52 in the spring and the inner or lower cross bar` 53 engages a selected :one of la plurality l of notches 1254 @in the outer edgelof weight y"I1, thereby-I eiiectinga fulcrum or pivotal Iengagement therewith. From the point :of Lview of feliminating zfriction, rit is desirable that .link $50 make knife-edge, line or pointcontact with :spring M2 and weight I. |11, :but in practice tthisAadvantage:mustfbefcompromised withithegdisadvantageof thefmore rapid wearing to Lwhich 'a point for Eknife-edge fon fthe link V'is subjected. Rounded engaging :edgeson :the link have -'been "found 'avery satisfactory rfrom the pointsiofnview of substantial elimination of 'frictionfand satisfactory wearingfqualities. To prevent displacement 'fof link +50 iduring operation spring 42 zmay rbe extended `and reversely abent to .provide :a retaining itongue 255 which -Vextends through the `center of the vlink :outlof `contact therewith but'suiiciently close to'bar '51 :to prevent accidental disengagementof the llink from the lspring recess 52. A leaf spring-retainer `fili passes through linki50 `inproximity to-cross bar 53,:butrout of normal contactatherewithfandhas bifurcated ends :51 Vvwhichfengage `notches 58 in oppositely facing shoulders 'on-weight' lfl. The retainingstrip L56 preventslink 50 -frombeing accidentally disengagedfrom -a selected notch'54 but iyieldabl-y permitsvanoperatorA to ymove `the link -"from one notch toLanother for eifecting an adjustment, fthe :purpose andi-effect `of which will appear herein'after.

The spring 642 fthusexerts -a continuing pressurethrough'link 50 against the yweights so as to loadthemfcentripetally and 4`yie'ldably hold them in limiting, innermost position with the abutments :'43 voi each `pair fof flyweights Amaking contact with :flat areas 7on the .gear segments i 5 and flS. The -outer vsurfaces r of the ilyweights have lportions 59 that arevpreferab-ly concentric with and engage the abutment rings when the weights are in centrifugally energized-or outermost position -to limit :the youtward vmovement thereof.

Another form-of adjustability isobtained in this preferred :struetureiby a changein leverage seoured'by movingthefa'butment ring 40, for example, with lrespect to v-tlle-ilyweight Il'! sot-hat the-spring 42 Ainterposed between the yring and the weight "is shifted Vbo'dily relative to xthe weight. The leverage of the spring -or weight will ibe equal 'inreach position to l:the -distance between 4the l point at `which* the llink 50 engages the :fflyweight surf-'ace and the center of the supporting @pin |14 on which the weight lis pivoted.

age rand strength of .the springs 'and the spring rates thereof. y'By means of the two modes of adjustment'mentifoned abovef.

fa practical matterfdevices Iembodying the .present invention are usually -designed ffor vpanticular iuses, such :as Afor use .on va given type of engine, -for accomplishing a certain predetermined mode of operation. In such instances'the parts lare designed and assembled to providefas nearly asv possible the desired'mode of operation when the lcenter of gravity of the vpoints of engagement o'f link 59 with Vthe yweight and'controlspringfare on or near the sameradial line'ipassing through the axis of rotation 'to thereby substantially lbalance "the weight on pvot 50, 54 and thus vminimize friction at pivot :114. This ideal is, of course, substantially a mechanical point of `viewbecause of manufacturing -tolerances .and because of fthe substantial impossibility of manufacturing large'quantitiesof identical springs having the same springrates, i. e., springs lwhich stien or yincrease intension an equal amount-for-equal during 'flong lperiodsof operation beeausevof the effects lo1 wear and the like. Accordingly, v'the adjustments provided by the present invention may '-'be utilized primarily to vcorrect for-manufacturing tolerances, theoretical inaccuracies'and errors introduced by usage of the-device. However, substantial adjustments can beeiected for attaining a'wide range and varietyof modes-of operation, thereby rendering any particular-device adaptable for a wide variety of applications.

Assuming now'that power is being applied to or bythe driving member i La `simultaneous and equal -rotation of all parts will occur at speeds below a predetermined speed at which outward movement of the heavy lyweights H isinitiated by centrifugal force. This movement of Athe weights is yieldably resisted vby the force exerted by springs 42 andby inevitable friction'so that the-centrifugal force must attain'a value 'slightly greater than the sum of these forces before the weight begins to move. By way of example, let

weghtagainstjpivotl 4 and hence friction at that point'wllb'e materially reduced.

.'As the, speed increases from a to b (Eig. `7) the driven member Aor shaft wis angularlyadvanced relative to driving member I I at a rate .and in "the Shy-Weight A and the weight and corresponding flection of the spring, the increase in centrifugal force exerted by the weight is greater than the increased tension or force of the spring, the weight will move to its outer limit very quickly without any iur-- ther increase in speed and the curve will approach the vertical. If the reverse is true, i. e., if the spring pressure increases faster than the centrifugal force for corresponding movements of the parts, the curve will approach the horizontal, increased speed being necessary to create sufficient centrifugal force to overcome the increased spring pressure.

In prior known devices utilizing simple leaf springs for controlling the movement of centrifugal weights, the slope of the operational curve has been varied in a haphaaard, hit'-or miss manner, such as by bending the spring beyond its elastic limit to effect a permanent deformation thereof. In the present device the same eiect is obtained and accurate adjustments are made possible without tampering in any way with the inherent characteristics of the spring. By setting the link 5U at different angles to the axis of the spring, i. e., by engaging it in different notches 54 in the flyweight with a given setting of ring All, a given outward movement of the weight may be made to cause either a greater or lesser movement of the spring and hence a larger or smaller increase in spring pressure for a given increase in centrifugal force exerted by the weight without increase in speed. When the spring pressure increasesl at a relatively high rate, the curve between speeds a and b will be relatively flat or horizontal whereas when it increases at a relatively low rate, i. e., at a rate only slightly greater than the rate at which the centrifugal force increases during a comparable movement of the iiyweight, the curve will be relatively steep or vertical.

Referring, for example, to the link 5i) shown at the left side of Fig. 2, it will be seen that as weight I1 swings away from the axis of rotation of the coupling, the right hand or inner end of the link engaging the weight will move to the left and upwardly (as viewed in the drawings) in an arcuate path whereas the outer end of the link engaging the spring will move in a path which does not parallel the path of the inner ring. When the link is initially tilted in a direction extending below a radial line r (Fig. 2) a given outward pivotal movement of weight I1 will tilt the link closer to line r and thereby impart a somewhat greater movement to the end of spring 42 so that the effective force exerted by the spring will increase at a greater rate than the centrifugal force exerted by the weight. If the link is set or is moved to a position such that it is above the radial line 1, i. e., a radial line connecting the axis of rotation and notch 52, outward movement oi weight Il will cause the link to tilt further away from said radial line and hence a given movement of the weight will impart a somewhat lesser movement to the spring so that the increase in spring pressure will be correspondingly less than the increase in centrifugal force resulting from each increment of outward movement of the weight. It will thus be seen that varying the initial angular setting of link 50 has the same effect as varying the spring rate of the spring. It will be understood that when the spring force increases faster than the increase of centrifugal force resulting from movement of the centrifugal weight, continued outward movement of the weight will be eiiected only by increasing the speed to thus gain increased centrifugal force without at the same time increasing the spring pressure.

When speed b has been attained weights I1 will have moved into engagement with ring 40 so that further relative movement or advancement of member I2 thereby is prevented as the speed is further increased. When a predetermined higher speed c is attained, the weights I8 will start to swing outwardly and effect relative angular movement of the driving and driven parts, opposite in direction to that effected by the outward movement of weights I1, to cause a retardation of the spark. The speed at which retardation of member I2 is initiated is determined primarily by the size of weights I8, the strength of the springs 42 resisting movement thereof, and the adjusted position of the parts. This relative movement is represented by the declining portion of the curve (Fig. 1) between speeds c and d. As explained above, the slope of this curve may be varied by changing the angle or tilt of links 50 which engage weights I8. and the speed at which this relative movement begins to take place may be varied by varying the length of the leverage arm, i. e., the distance between pivot I4 and the point at which link 50 engages weight i8. When speed d has been attained, the weights IB will have engaged ring lli so that further increase in speed will not effect further relative angular movement of the driving and driven shafts. It will be understood that by reversing the mounting of weights IS driven member I2 may be further advanced rather than retarded relative to driving member II between speeds c and d. By the same token the relative movement between speeds a and b may also be reversed if desired by changing the mounting of weights I1 or by reversing the direction of rotation.

When the speed of the unit is decreased from a speed greater than speed d the weights I8 will not be swung inwardly by springs 42 until the pressure exerted thereon by the springs exceeds f, the sum of the centrifugal force exerted by the weights and the frictional and other inherent forces tending to resist such inward movement of the weights. Accordingly, initial reverse or inward movement of the weights I8v will not occur until a speed d somewhat lower than speed d, has been reached, i. e., a speed at which the centrifugal force of the weights has been sufficiently reduced to compensate for the forces of friction and the like. The same applies to the inward movement of weights I1 which indicated as beginning when speed b' has been reached. Therefore, as the speed decreases the curve d', c', b', a will be followed. In some installations it is desirable to effect operation as nearly as possible along the same curve for both increasing and decreasing speeds. The present invention approaches this ideal by materially reducing the undesirable frictional forces.

There is thus provided a simple and eiective coupling for rotating parts which will permit and control limited relative angular adjustment of said parts during operation and automatically in response to the varying speed of the parts. Additionally, the coupling contemplated is so constructed as to make it possible by easy adjustments to effect numerous different modes of operation and to accurately compensate for minor manufacturing and theoretical inaccuracies in the construction and design. Although the `means of adjustment are relatively rugged, the

several suchk means providedk are sorelatedthat When-,used in conjunction with eachother eX- tremely ne andi accurate adjustments may be made to'V effect almostv any desired operation at or between-selected speeds. The constructionis such; as to permit-easyA variation of the rate at which angular adjustment of the parts takes place in response to speed changes and also permit variation of the speed at which such adjustment is initiated. Thestructure in its simplest form comprises onlyV asmall number. of rugged parts which may be readily and inexpensvely manufactured and assembled.

Although only a limited number of embodiments or modifications of the invention are illustrated in the drawing and described in the foregoing specication, it is to be expressly understood that the invention is not limited thereto. For example, suitable known means other than gear teeth may be empl-'eyed for operatively connecting the flyweights and members Il and I2. Although each set of Weights Il and. I8 comprises only two weights, it will be clear that the number in each set may be more or less than two. Also, only one or one set of weights may be required in some installations, while in others the number of sets of weights may be increased. As illustrated, spring 42 has only one notch I'52 for engagement by link 50 but the invention contemplates possible adjustment of the contact point between parts 50 and 42 such as by providing a plurality of such notches. Other known types of low friction conneotions may be used in operatively connecting link 50 to the spring and weight. Various other changes may also be made particularly in the design and arrangement of the parts illustrated without departing from the spirit and scope of the invention as it will now be understood by those skilled in the art.

What is claimed is:

l. In apparatus of the class described, rotatable means, centrifugally actuatable means and resilient means mounted on said rotatable means, and link means interposed between said resilient means and said centrifugally actuatable means for transmitting the force of the resilient means to said centrifugally actuatable means to resist movement of the latter in response to centrifugal force, said centrifugally actuatable means being selectively operatively engageable by said link means at any of a plurality of notches in and at different distances from the pivotal axis of said centrifugally actuatable means to vary the leverage thereof with respect to said resilient means.

2. In apparatus of the class described, rotatable means, weight means rotatable therewith and pivotally mounted thereon for centrifugal movement about an axis eccentric and parallel to the axis of rotation of said rotatable means, resilient means mounted on said rotatable means, and pivoted pressure-transmitting means interposed between and wholly supported by said resilient means and said weight means independently of said rotatable means whereby said resilient means is effective to yieldably resist centrifugal movement of and impart centripetal movement to said weight means.

3. Apparatus as defined in claim 2 wherein said resilient means is constituted by a leaf-type spring.

4. Apparatus as defined in claim 2 wherein said pressure-transmitting means comprises a thin plate-like member having edgewise engagement with at least one of 'said weight means andsaid resilientmeans.

5. Apparatus as defined in claim 4 wherein said member is selectively operatively engageable with notches in at least one of'saidweight means and said resilient means at spaced'points thereon at different distancesfrom the mounting point of said one means to vary the eiective force of said resilient means for any given position of said weight means.

6. A coupling for drivably'connecting rotatable members comprising' centrifugally actuatable weight means for imparting relative angular movement to said' members, said weight means being pivotally. mounted on an axis parallel to the` axis of` rotation of said members, resilient means Vfor resisting vcentrifugal movernentofsaid weight means, and one-piece substantially rigid motion-transmitting means interposed between, wholly supported by and having direct pivotal Contact with said weight means and said resilient means.

7. In apparatus of the type comprising a rotatable driving member, a rotatable driven member and means connecting said members to iinpart rotation from said driving member to said driven member, said means including centrifugally actuated weight means pivotally mounted on one of said members and operatively engaging the other member to move said members angularly relative to each other in response to pivotal movement of said weight means, the combination therewith of means for controlling the pivotal movement of said weight means comprising a leaf-type spring for yieldably resisting centrifugal movement of said weight means, and link means pivotally engaged with said weight means and said spring for transmitting the force of the spring to the weight means, said link means comprising a plate-like member having edgewise engagement with said weight means and said spring.

8. In apparatus of the class described, a rotatable driving member, a rotatable driven member, means for drivably connecting said members including a plurality of centrifugally actuatable weights pivotally mounted on one of said members and comprising portions which mesh with gear teeth on the other of said members whereby said members are adapted to rotate together and are movable angularly relative to each other in response to pivotal movement of said weights, a spring mounted on said one member for yieldably resisting the pivotal movement of each of said weights, and link means interposed between each of said springs and the weight controlled thereby for transmitting the force of the spring to the weight.

9. Apparatus as defined in claim 8 comprising means for supporting said springs on said one member to permit simultaneously adjusting said springs relative to said weights, said supporting means including a supporting member mounted on and for angular adjustment about the axis of rotation of said one member.

10. In apparatus of the type comprising a rotatable driving member, a rotatable driven member and means for drivably connecting said members including centrifugally actuated weight means pivotally mounted on one of said members and operatively engaging the other member whereby said members are adapted to rotate together and are movable angularly relative to each other in response to pivotal movement of said weight member, the combination therewith of means for controlling the pivotal movement of said Weight means comprising resilient means for yieldably resisting centrifugal movement of said weight means, and link means pivotally engaged with said Weight means and said resilient means for transmitting the force of the resilient means lto the Weight means, said Weight means having spaced notches thereon selectively engageable by said link means.

11. In apparatus of the class described, rotatable means, centrifugally actuatable means and resilient means mounted on said rotatable means, and link means interposed between said resilient means and said centrifugally actuatable means for transmitting the force of the resilient means to said centrifugally actuatable means to resist movement of the latter in response to centrifugal force, said link means being adjustable to selectively engage any of a plurality of spaced notches in and at different distances from the mounting point of at least one of said centrifugally actuatable means and said resilient means for varying the leverage of said centrifugally actuatable means with respect to said resilient means.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,089,256 Pardee Mar. 3, 1914 1,130,177 Kramer Mar. 2, 1915 2,050,340 King Aug. 11, 1936 2,549,748 Purdy Apr. 17, 1951

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