US2287417A - Toggle - Google Patents

Description

June 23, 1942. P DE MATTlA l 2,287,417

TOGGLE Filed Feb. l1, 1941 2 Sheets-Sheet 1 ,l Mrllml n f Q Wf Num A H 35 /g Ue wk QR I6 /5 ZZ Z55/Z BY 57 55 54 s@ j MTM Juxne 23, 1942. P. DE MATTIA` '2,287,417

ToGGLE Filled Feb. 11, 1941 2 sheets-sheet 2 Patented June 23, 1942 UNITED STATES ATE-NT OFFICE TOGGLE `Peter De Mattia, Passaic, N. J .Y

Application February 11, 1941, SeriaLNo. 3718.388 22 Claims. (Cl. 74-10(i') This invention .relates to toggles and similar devices.

One object ofthe invention is to provide a device comprising a plurality 'of links Vconstructed in an Aimproved manner for direct pivotal abutment between `the elinks to zavoid yshearing strain on gpins, especially in or near dead center position.

Another object of the invention is to provide a -devi'ce comprising spaced relatively movable members, and means vcomprising links interengaged for direct abutment with each yother and with at least oneof the members in an improved manner vto avoid vpin shearing stresses.

Another object of the invention is -to furnish a device as set forth vhavin-g improved .means for direct abutment 'along surfaces yrolling `on each other in course of pivotal movement.

Another object `of ythe invention is the provisionof a device comprising-a'toggle @having a pivotalzlink arranged or constructed `in animproved manner to exert an abuttingpressure throughout a plane ,surface .area for'maximum ,resistance against a compression load.

Another object of the invention -is -to ,turnishi a device as referred ito .having :improved ,pvotally `interengaged elements v directly abutting in rolling interengagement. coaxially with connecting bearings in which the pivotal movement tis limited, wherebythe'devce is easily zcontrolled :if: l

lone of the elements :has a temporarily `free end.

lAnother 'object -of -the invention is to provide a device -including a linkage one end of which vis desirably connected -to a movable member and the other endof which fis :movable into :and out of engagement ,with -a fixed member, at vleast part of the linkage-being loperable l.to initially move the movable member andthe linkage being 1then Yengaged with the fixed member for Afinal :movement -of the -linkage to dead center position,

Vwhereby compactness is increased, and-'the wrange of lmovement 'of the Vmovable member is increased, and Ifewer .bearings are required, and a simplied actuator means lis 'available for utilizing `part vof the lin-ka'geto y'cause the said initial arrangements of parts hereinafter described in their preferred embodiments, pointed out in the subjoined claims, and illustrated in the annexed drawings, wherein like `parts .are .designated by the `same reference characters throughout .the several views.

-In the drawings:

Figure v1 is .a .diagrammatic sectional View' .showing a dev ice .embodying the invention.

Fig. 2 is an isometric view o'f alink embodying the invention.

Fig. 3 -is a diagrammatic .view with parts in section showing .a modcaton of the -invention With a linkage in dead .Qenterposition Fig. 4 is a similar view thereof but. ,sl1o. wingfthe linkage y of Rig. 3 ,in open or collapsed position.

Fig. 5 is a sectional view taken on the line 5-5 of Fig. 3.

Fig. 6 is a fragmentary .diagrammatic view showing a modification tin .dead .Center POSiOn Fig. -7 is a similar vView of still a )urther modification in yopen position.

Fig. 8 .is a fragmentary plan v iewshowing the preferred vform vof .the invention as .applied to a molding vmachine or the like.

The advantages of the invention as here outlined are best realized when ,allof its features and linstrumentalities are Combined in one `and the same structure, but, useful devices may be lproduced embodying less than the whole.

It will be obviousto those skilled'in the art to which the invention appertains that the same may be incorporated in several different constructions. The accompanying drawings, therefore, are submitted merely as showing the preferred exemplirlcation of -the invention.

Referring in detail tothe drawings, I0 denotes a device embodying 'the invention. The same may include relatively 'fixed and movable members II and `I2 respectively, the member I2 being movable in a straight path, and vany -motor I3 movable parallel to said-path'and being adapted to cause'reciprocation of `fthe Vmember "I2, For transmitting power fromt-he motor to -the lmember I2, la toggle I4 'is provided, which may include links 1I5that may be iidentical with each other.

As shown inFig. 2, -eachmember I5 may-consist of a plane plate fof uniform thickness and being of the shape of arectanglaexceptsthat it may `have segmental shafts I6 vand I'I integrally projecting therefrom. Each :olffsaid shafts is kin cross section less than a --semiirc1 e,;and each-is bounded by a section ora-cylindrical surface at I S, the diameteriof vwhich is substantially fequal to the thickness of the plate. The opposite or outer sides of each segmental shaft I6 and I1 is formed by two plane surfaces I9, 20 forming an obtuse angle with each other. The surfaces I9 constitute the normal edge surfaces of the plate I and are at right angles to the plane thereof, and may extend continuously along the segmental shafts. The surfaces are parallel to each other, and also form continuous surfaces along the 'ends of the `link and along the segmental shafts I 6, I1. Both surfaces I9 and 20 are radial to the axis of their segmental shafts,

and thus the areas of both are substantially.

equal.

It will thus be apparent that the segmental shafts I6, I1 are actually duplicates of each other, except that in angular relation, one is at 180 degrees relative to the other. It will be further perceived that the plane surfaces I9, 2i)Y at an end of the link may be considered as forming a generally convex surface; in fact, they may be replaced by a segment of a cylindrical surface except that the abutting pressure in dead center position would be Yalong a line of tangency, instead of along the large area afforded by a plane surface. The latter possesses the advantage of maximum distribution of bearing pressure and is thus less subject to distortion and wear than a curved surface. Within the scope of the invention, the term convex surface denotes both. Infact, the surfaces I9, 20 are curved along their line of intersection 2| to reduce wear and distortion; such curvesare also afforded at similar'intersecting surfaces of the other modifications herein.

When two links I5 are placed end to end, as in Fig. 1, adjoining segmental shafts I6 and I1 form in effect a single shaft or pin Which may be received in a circular collar or bearing such as 22 so that the cylindrical faces I8 are in contact with the cylindrical faces of the bearing. But due to the angularity of the surfaces I9 and 20, free radial spaces, such as sectors of a circle result which afford clearance for a relative angular movement of the shafts I6, I1 and hence of the links I5.

Any suitable bearing elements such as the yokes or collars 23 may secure the different segmental shafts I6, I1 to the members II and I2'. Desirably the adjacent faces 24 of these members are plane for abutting contact with the surfaces I9 when vthe linkage is in dead center position as shown in Fig. 1. In that sense the members II and I2, or at least their surface portions such as 24 are herein considered as parts of the bearings, and the term bearing as here used is intended also to apply in the modifications hereinafter described.

To actuate the linkage I4, a link 25, of which the bearing element 22 may be a part, may be connected to the motor I3 at a Suitable angle.

In operation, when the motor or cross head I3 moves to the right, the link 25 pulls downward on the linkage I4, collapsing the same and pulling the member I2 rightward. Downward movement of the linkage is limited by abutment of the facesv at 24, and by abutment of the adjacent faces 2U with each other. While such stop action is desirable, it is not absolutely essential, since the device I3 may aiford a stop. But it is essential to cut away as little metal as possible especially at the shafts I 6, I1 and hence in a carefully designed device, the faces "20 Will move to the limit of movement. 'Ihis observation applies to all the forms of the in vention herein disclosed.

Further considering the operation, when the device I3 moves leftward, the link 25 pushesthe linkage I4 upward and toward the left, causing a leftward movement of the member I2 and moving the linkage I4 to the dead center position shown in Fig. 1. As this movement proceeds, the surfaces I 6, I1 roll on adjacent surfaces in the same way as if they were circular. 'Ihus such rolling occurs on the surfaces 24 and on the adjacent surfaces I6 and I1. In other words, there is no sliding motion, hence no friction. There are no pins to shear. In dead center position, extreme power is attained, and actually the linkage I4 forms a very powerful column which is capable of exerting many hundreds of tons of-'compressive force, although the stress per square inch is relatively low. This feature is of substantial importance in presses and molding machines, in which wear, and abrasion rapidly occurred. To withstand the extreme stresses, the toggles used were of hardened steel and hence subject to fracture under shock.

It is thus an important advantage of the invention that the links such as I5 may be made of a low grade steel, suitably carburized to form a strong hard surface portion with a tough softer interior to take the shock. y

It is important to note that while the surfaces I9 and 20 may have rolling abutting engagement within the different bearings, this is not really essential, and it is sufficient that the segmental shafts I6, I1 act as pivotal connectors. The body or link proper affords sufficient abutment area for all necessary purposes. Hence the surfaces I9, 20 may be spaced out of abutment within the different bearing elements, but ease of manufacture calls for uniform continuous surfaces I9 and 20 throughout. These observations apply also to the other forms of the invention.

In Figs. 3, 4 and 5 is shown a modied form ofthe invention which represents the preferred embodiment, being the one which I have-found best suited in actual use in a molding machine; Whereas the device IIJ serves as a simplified illustration of the invention. In the device 26 are spaced relatively `movable members of which 21 may be fixed and 28 movable. Interengaging these is a linkage 29 comprising the link I5 and a link 30. 'Ihe latter differs from the link I5 only in its physical dimensions and in the fact that it is in only temporary engagement with the member 21,'having a flat, free end portion or heel 3| engageable in a recess 32 of the member 21. Because the linkage is not connected to the member 21, it is normally inclined at an angle in its dead center position as shown, so that the link portion 3| is'laterally forced into the recess 32 and cannot slip therein. In consequence, the surface 24 of the device I0 is modified to provide a surface 24a terminating at the center of the bearing 23, and a surface 24h which is recessed into the member 28 to lie at an angle so as to be at right angles to the linkage when the latter is in its dead center position. Instead of the element 25 of the device I0, a crank-like member 33 is provided which may include the bearing 22 as a part thereof. Extending through the link 30 and the members 33 which are at both sides of the toggle is a lpin 34, which engages the links 35 that are pinned at 36 to a head 31 that moves in parallel relation to the path of the member 28. To facilitate outward movement of the link 30, an arm '38 rigid on the member 31 may have cam or wiping engagement with the link 30 as 'oper-ating with this-link 401 is av recessed portion thelmember 31Jmoves leitward.

In'operation, Fig. 4'- inV plan View shows the device 26 collapsed with-the member 29 retracted toward the right. In the bearing 23, the surfaces 20 and 24o. are inabutment; in the bearing 22, the surfaces 2U? are in abutment. The-link 30 is inclined outward with its end portion beyond the recess-32 andinside or beyond the adjacent part of the member 21. Thus it isv seen that the spacingbetween the members 21 and 28 may be-reduced-to be less than the length of the toggle 29 when collapsed. The element 30 is desirably in wiping ory sliding contact with the inside-face of the member- 21l which thus serves as a guide for the free end of this element 3D'. An important feature of the invention is that the seat at 32' is laterally outward or beyond the bearing at 23, with the toggle of Fig. 3 being at an angle as shown.

Due to the angle of' the element 35, when the member 31` moves toward the left, it causes a leftward travel of the member 28, the free end of the element 3| sli-ding along the member 21. The member 28 initially offers little resistance, and the inward break in the toggle at the bearing 22, with the application of power at the pin 34 permits this movement to occur. As the heel 3| moves into line with the recess 32, the resistance of the member 28 may be considered to have increased, and hence the toggle may begin to straighten out; or if the resistance of the member k28 is still low, the latter may be moved to its end position at the left substantially as in Fig. l, and then the toggle may straighten out. As the member 31 continues its movement toward the left, the arm 38 assures that the-link 39 moves outward sufliciently to be fully received in the recess 32. Then the toggle attains its dead end position as in Fig. l. It need not be moved past `dead end position, because the flat bearing surfaces assure a reliable locking irrespective of the members 35 and 31. The member 39 may be omitted if preferred.

In the dead center position, the surface 20emgages surface 24h, and surfaces 20 engage in the bearing 22, and the heel engages the wall of the recess 32. All these provide large abutment areas that are substantially in alinement with each other.

The importance of the inclined or angular position of the toggle 29 when in dead center position as in Fig. 3 will now be apparent; in fact, if the toggle were parallel to the path of the actuator 31, the operation would-not be satisfactory. This is believed to be more clearly apparent by reference to Fig. 8, which is like the devices of Figs. 3 and fl, except that it shows two toggles according to an actual installation, When the actuator 31v moves to the right, the angularity of the straight toggles assures an accentuated force tending to break the toggles, and assures that the break occurs before the free end portion 3| of the link 3D is caused to leave its recess 32, and no binding occurs. In fact, the principal reason for providing the free end portion 3l is to realize in a high degree the advantage of the angularity of the straight toggle. When the actuator 31 moves toward the left, there is facilitated the movement of the member 28, then the engagement of the link 30`in the recess 32 and iinally the straightening of the toggle.

In Fig. 6 is shown a modiied device 39 which is intended to illustrate that one of the links such as 40 may be free of the inclined faces 29.

lli in the movable member 42. Thesecond link 43'may be likethe linkt 30, but the inclined face Zllthereoff mayY be at al larger angle than before. The-segmental shaft l-Sthereof isin rolling abutment withthe plane right angle end face 44 of the link49; and the like face 49' at the other end of' the link isv in rolling abutting engagement with the face ofthe member 42 including the recess 4| thereof. The device 39 may include the actuator means of the device 26.

In Fig. '1Y is showna modied device 95 to illustra-te that no connecting bearings are needed at either the fixed` nor movable members 46, 41. These may be provided'with like stepped formations 43, and thelinks 49 may be duplicates of each other, each having segmental shafts 50 like those at l5 engagedin bearings 22 of the actuator 25. The plane right angle end faces 5| have rolling abutting engagement with the stepped formations-@las indicated in-the device 39. Retraction of the-movable member 41 may be caused by a tensionl spring 52 or other actuator. The linkage actuator may serve to support the linkage-when the latter iscollapsed as shown. In Figs. 6 and 7, the surfaces at 4l and 48V afford convex abutting faces.

I cla-im:

1'. A device including a relatively fixed first member, a reciprocabley second member for delivering a power stroke, a toggle whereof one link is connected to the secondmember and the other link is separably engageable with the first member, actuator means for expanding and co1- lapsing the toggle and for reciprocating the toggle to an extent less than the path ofmovernent ofv the secondl member, the separable link being adapted to move laterally away from the first member in the collapsing position of the toggle, said actuator means causing said lateral movement of the separable link and causing the connected link to retract: the second member, the actuator means causing the connected link to initially advance the second member and moving the separablelink into engagement with the rst memberQ and nally causing the toggle to movesubstantially to dead center position, and stop means for limiting the lateral movement ofthe separablelink to cause the toggle to assume a predetermined expanding position.

2. A device including a relatively fixed first member, a reciprocable second member for delivering a power stroke, a toggle whereof one link is connected tothe second member and the other link is separably engageable with the first member, actuatormeans for expanding and collapsingA the toggle and for reciprocating the toggle to an extent less than the path of movement of the second member, the separable link being adapted to moven laterally away from the nrst memberv in the collapsing position of the toggle, said' actuator means causing said lateral movement of the separable link and causing the connected link to retract the second member, the actuatormeans causingthe connected link to initially advance the second member and moving the separable link vinto engagement with the rst member and iinally causing the toggle to move substantially to deadv center position, and stop means for limiting the lateral movement of the separable link. to cause the toggle to assume apredetermined expanding. position, said toggle when in dead center position lying Yat an angle to the path of the second member so that the separable link laterallyv abuts the stop means.

3. In a toggle link mechanism, the combination of two spaced relatively movable members, and a linkage adapted to interengage said members, comprising a pair of links, and a bearing means interconnecting the same comprising a pair of fragmentary shafts which extend along each other and are adapted for relative angular movement about the axis of the bearing means, each of said shafts affording a fragment of a cylindrical surface and each being nonrotatably connected to its respective link, and a cylindrical collar engaging around said shafts in engagement with both of said fragmentary cylindrical surfaces, and at least one of said links having another like fragmentary shaft directly pivotally abuttingone of said members.

4. A device including a relatively fixed first member, a reciprocabl'e second member for delivering a power stroke, a toggle whereof one link is connected to the second member and the other link is separably engageable with the first member, actuator means for expanding and collapsing the toggle and for reciprocating the toggle to an extent less than the path of movement of the second member, the separable link being adapted to move laterally away from the iirst member in the collapsing position of the toggle, said actuator means causing said lateral movement of the separable link and causing the connected link to retract the second member, the actuator means causing the connected link to initially advance the second member and moving the separable link into engagement with the first member and finally causing th'e toggle to move substantially to dead center position, and stop means for limiting the lateral movement of the separable link to cause the toggle to assume a predetermined expanding position, said actuator means including a power element reciprocable in generally parallel relation to the second member, a link connecting the power element to the toggle for operating the latter, and an arm on the power element for releasably engaging the separable link as the second member is being advanced to laterally move the separable link into engagement with the stop means.

5. In a toggle mechanism, the combination of two spaced relatively movable members, and a linkage interengaging said members and adapted to powerfully move the same apart in the dead center position of the linkage, a first bearing means interengaging the links of the linkage, a second bearing means engaging one of the links with a first of said members, at least one bearing means comprising shaft portions adapted for rolling engagement with each other, the said links having portions having direct rolling engagement with each other about the axis of the first bearing means, the link at the second bearing means having a portion having direct rolling engagement with said member about the axis of the second bearing means, said axes being transverse to said links, the link having engagement with the second of said members being movable into and out of engagement therewith, and actuator means connected to the last mentioned link for moving the latter into and out of said engagement and for thus causing expansion and collapse of the linkage.

6, A device including a relatively fixed first member, a reciprocable second member for delivering a power stroke, a toggle whereof one link is connected to the second member and the other link is separably engageable with the first member, actuator means for expanding and collapsing the toggle and for reciprocating the toggle to an extent less than the path of movement of the second member, the separable link being adapted to move laterally away from the first member in the collapsing position of the toggle, said actuator means causing said lateral movement of th'e separable link and causing the connected link to retract the second member, the actuator means causing the connected link to initially advance the second member and moving the separable link into engagement with the first member and finally causing the toggle to move substantially to dead center position, and stop means for limiting the lateral movement of the separable link to cause the toggle to assume a predetermined expanding position, and means operated by the actuator means for releasably engaging the separable link for moving the same into engagement with the stop means.

7. A device including a iirst member movable along a path, mechanism comprising a toggle linkage comprising a plurality of links pivotally interconnected, one of said links being connected to the first member, the second link being movable into and out of engagement with the second member, and actuator means movable along a path parallel to that of the first member, comprising a link element connected to the second link at a point intermediate of the axis of pivotal connection and the second member. said actuator means being movable to cause the link element to pull on the linkage to break the toggle and to retract the first member, said mechanism including means to limit the breaking movement of the toggle linkage, `and the actuator means being movable in an opposite direction to cause the link element to move the linkage for causing a forward movement of the first member and a swinging movement of the toggle linkage with the second link being moved into engagement with the second member and the toggle linkage being finally moved to dead center position by said link element under continued movement of the actuator means.

8. A device according to claim "I, wherein said actuator means includes a cam means for engaging the second link to urge the same into engagement with the second member in course of movement of the actuator means.

9. A device according to claim 7, wherein the toggle linkage in its dead center position extends at an angle to the path of travel of the first member, the second member having a recess for engaging and retaining the end of the second link in the dead center position.

10. A device including a toggle means comprising a toggle link consisting of a plate having at one end a surface convexed in a direction transverse to the thickness of the plate, said plate having side projections having convex surfaces forming straight continuations of the convex surface of the plate, said projections constituting fragmentary shafts Whose common axis lies along the center line of the convex surfaces.

ll. A device including a toggle means comprising a toggle link consisting of a plate having at one end a surface convexed in a direction transverse to the thickness of the plate, said plate having side .projections having convex surfaces forming straight continuations of the convex surface of the plate, said projections constituting fragmentary shafts Whose common axis lies along the center line of the convex surfaces, means having fragmentary shafts substantially complemental to those first mentioned, but one set of the shafts being cross-se-ctionally less than the other vso that said fragmentary shafts are adapted' for pivotal movement 'relative to veach other, and 'bearing elements interconnecting vthe adjacent shafts.

f12. A device including power means comprising a `relatively xed rst member, a reciprocable .second power member, a toggle whereof one link'is connected to .the second member and .the second link separablyengageable with the first member, .said .toggle being vmovable substantial- 1y to dead center position between the members for moving said members .apartsaid toggle'being collapsible with the separable link movable clownward for partially underlying the first member, the power means having means for limiting the angular movement of .the toggle, a :power felement reciprocable in a path extending vin the general direction of reciprocation of the :second member, and actuator means operated bythe power element for operating the toggle and `in cooperation with said limiting means, for recip rocating the toggle .to an Aextent less than the path of Vmovement of the second member while moving the second link upward and downward according to the dead center and collapsed bosition of the toggle, the lactuator means :thus causing the second member to move away from the rst member vto make room for the separable link whereby the toggle is engaged between vthe members for the power stroke of the second member.

13. -A device including a ,power means comprising a relatively fixed first member, a reeiprocable second power member, a toggle whereof one link Vis connect-ed tothe second member and the second link separably engageable with the first member, said toggle being movable substam tially to dead center .position between the memn bers for moving said members apart, said toggle being collapsible with the separable link mov able downward for partially underlying the first member, the power means having means for limiting the angular movement of the toggle, a power element reciprocable in a path extending in the gener-al direction of reciprocation of the second member, and actuator means operated by the power element for operating the toggle and in cooperation with said limiting means, reciprocating the toggle to an extent less than the path of movement of the second member while moving the second link upward and downward according to the dead center and collapsed posiftion of the toggle, the actuator means thus causn1 ing the second member to move away from the rst member to make room for the separable link whereby the toggle is engaged between 4the members for the power stroke of the second member, said actuator means including a link interconnecting the power element with the sep-- arable link at a point intermediate of the ends of the latter, with the link of the actuator means being generally parallel to the connected link of the toggle in the collapsed position of the lat ter, and the toggle cooperating with the actuan tor means and the power element to limit the collapsing position of the toggle for obtaining said generally parallel position.

14. A device including a mechanism comprising a plurality of spaced relatively movable members, and a toggle therebetween comprising pivotally interengaged link members adapted for pivotal engagement with the adjacent respective relatively movable members, all of said members having interengaging means for pivotal rolling engagement between the toggle and at least one of the relatively movable members, andbetween the `linkmembers, each of said means :comprising a convex surfaoefportion on one `member c0- operating in direct abutment with a surface p0rtion on an adjacent member "for rolling onithe convex surface l.portion in lcourse of operation of the toggle, each .convex surface `portion comprising surfaces atan obtuse angle to .ea-.ch other, certainof said :surfaces V.being plane and being so locatedas to take the'dlrect-abutment'pressure when the toggle is in dead center position. 15. Adevice including a `relatively fixed first member, a reciprocable secondmemberl'for delivering a power stroke, --a-toggle whereof `one link is connected Ato the A-secondmember and vthe other link is separably engageable with the -rst-member, actuator means for expanding and collapsing the toggle `and `for reciprocating the toggle to Ian extent less than the Apath 'of movement of the second member, the separable link :being adapted to Ymove laterally away from the flrst member in the collapsing position of the toggle, said actuator -meanscausing said lateral movement of the separable link and causing the connected link vto retract the second member, the actuator means causing the connected link to initially advance the -secondmember and moving the separable link into engagement withthe first member and nally causing the toggle to move substantially to dead center position, and stop means for limiting the lateral movement Of Lthe separable link to causetlie toggle :to assume a predetermined expanding position, the connected link and the second member having engagement means and the links having like engagement means therebetween, Said engagement' means having angularly related relatively rplane abutment surface portions providing at least one convex surface for flatwise abutment at one or another of the surface portions according as the toggle is in dead center or collapsed position.

16. A device according to claim l5 wherein the connected link has fragmentary shafts at its opposite ends and the separable link has like fragmentary shafts at its adjacent end, said surface portions being extended along said fragmentary shafts, and bearings for the fragmentary shafts including a substantially half circle bearing connecting the conected link to the second member and a full circle bearing interengaging adjacent shafts of the links.

17. A device including a plurality of members movable relatively to each other, means for caus ing said relative movement comprising a toggle, and means for actuating the toggle, said means having bearing means, including angularly related relatively plane abutment surface portions providing at least one convex surface, for flatwise abutment at one surface portion with other surface portions being angularly spaced from each other in an expanded position of the toggle, whereby non-rolling abutting engagement is obtained in course of movement of the toggle.

18. A device including a plurality of members movable relatively to eachother, a first means for causing said relative movement comprising a toggle, and means for actuating the toggle, said first means having bearing means, including angularly related relatively plane abutment surface portions providing at least one convex surface, for flatwise abutment at one surface portion with other surface portions being angularly spaced from each other in an expanded position of the toggle, whereby non-rolling abutting engagement is obtained in course of movement of the toggle, and at least one fragmentary shaft forming an extension of at least one of said surface portions, and a bearing engaging around said shaft.

19. A device including a plurality of relatively movable head members and a toggle operatively associated with said members including a plurality of link members, one of said members having relatively plane surface portions at an angle to each other to define a convex abutment surface, and an adjacent member having an abutment vsurface portion cooperating therewith so that as the toggle is expanded or collapsed one or another of the relatively plane surface portions comes into engagement with said cooperating surface portion for a non-rolling abutting contact.

20. A devicefincluding a plurality of relatively movable head members and a toggle operatively associated with said members including a plurality of link members, one of said members'having relatively plane surface portions at an angle to each other to dene a convex abutment surface, and an adjacent member having an abutment surface portion cooperating therewith so that as the toggle is expanded or collapsed one or another of the relatively plane surface portions comes into engagement with said cooperating surface, and a fragmentary shaft on one of the members having one face portion forming an extension of the abutment surface of said member, and a bearing for said shaft mounted on the adjacent member.

21. A device including a plurality of relatively movable head members, and a toggle operatively associated therewith, including a plurality of link members, one of the latter having a fragmentary shaft not greater than a semicircle in cross section, a bearing receiving and connecting said shaft to an adjoining member, the latter lhaving a surface portion in fixed relation thereto and cooperating with the bearing for coaction with the shaft, the shaft having a surface portion in fixed relation thereto and within the bearing adapted to directly abut the first mentioned surface portion in a substantially dead center position of the toggle, at least one of said surface portions having a convex abutment surface confronting and constantly contacting the other surface portion so that different parts of the convex surface become subject to abutment pressure as movement of the toggle progresses, whereby the abutment pressure is transmitted by generally rolling contact, as distinguished from sliding contact, directly between the said surface portions.

22. A device including a plurality of relatively movable head members and a toggle operatively associated with said members including a plurality of link members, one of said members having a convex surface portion, and an adjacent member having an abutment surface portion cooperating therewith so that as the toggle is expanded or collapsed the convex surface portion contacts the abutment surface portion at diiferent successive points for a rolling engagement about an axis, a coaxial fragmentary shaft on one of said members having one face portion forming an extension of the surface portion of said member, the other member having a surface portion cooperating with the surface portion of the fragmentary shaft to permit angular movement thereof, and a bearing extending around the fragmentary shaft for interconnecting the adjacent members.

' PETER DE MATTIA.

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