US2533197A - Trimmer mechanism for sewing machines - Google Patents

Description

Dec. 5, 1950 a. P. PINKVOSS TRIMMER MECHANISM FOR SEWING MACHINES Filed Feb. 6, 1947 4 Sheets-Sheet 1 albbozney Dec. 5, 1950 B. P. PINKVOSS mm macmmxsm FOR sawmc mcamns '4 Sheets-Shea 2 Filed Fb. 6, 1947 atbom'veu/ Dec 5, 1950 B. P. PiNKvoss TRIMMER MECHANISM FOR SEWINGYMACHINES '4 Sheets-Sheet 3 Filed Feb. 6, 1947 dktoeweq/ B. P- PINKVOSS TRIMMER MECHANISM FOR SEWING MACHINES 4 Sheets-Sheet 4 Fi] .ed Feb. 6, 1947 I; u. d w M e B Mbomau/ Patented Dec. 5, 1950 TRIMMER MEGHANISM FOR SEWING MACHINES Bcrthold P. Pinkvoss, Stratford, Conn, assignor to The Singer Manufacturing Company, Elizabeth, N. J a corporation of New Jersey Application February '6, 1947, Serial No. 726,909

17 Claims.

tions to reduce the speed of operation of the trimmer-knife as the speed of operation of the sewing machine increases and vice versa.

Another object of the present invention is to provide a trimmer-knife actuating mechanism with an improved form of latching means effective for maintaining the trimmer in its retract-- ed or inoperative position.

In prior combination stitching and trimmer machines, it has been customary to actuate the trimmer-knife a plurality of times for each reciprocation of the sewing machine needle to effect the production of smoothly trimmed edges about a sharp curve in the work. Such a machine is disclosed in the U. S. Patent of R. S. Painter, No. 2,108,138, issued Feb. 15, 1938. In the machine disclosed in this patent, the trimmer-knife is actuated from a separate electric motor which drives the trimmer-knife" at a constant speed. By varying the speed of the sewing machine from high speed operation during straightaway stitching to lower speed operation when stitching about a sharp curve, the ratio of the relative frequencies of reciprocation of the trimmer and sewing needle is increased from one to man times one. While the large number of reciprocations of the trimmer-knife relative to the needle produces a smooth seam about a sharp curve, the reciprocations are excessive and result in a rapid dulling of the trimmer-knife cutting edge as it repeatedly passes the cooperating stationary ledger-member or blade.

The present trimmer-knife actuating mechanism. is designed preferably to impart one reciprocation to the knife for each reciprocation of the need-lecturing the high speed operation of the machine, and then in response-to the decrease in.

the speed of the sewing machine automatically to increase the frequency of reciprocation of the knife relative to that of the needle, the increase being of the: order of about two or: three, to" one. The effect of. this speed responsive drive: is a reduction in the total number oi reciprocations of the: trimmer-knife past. its cooperating ledger- The present invention consists in the trimmer knife-bar actuating mechanism hereinafter described in connection with the accompanying drawings which illustrate a preferred embodiment of the invention and in which:

Fig. l is a rear side elevation of a sewing machine provided with the improved trimmer actuating mechanism, the lower portion of the sewing machine frame being broken away.

Fig. 2 represents a top plan View of the sewing machine with a portion of the bracket-arm in section to illustrate the gear drive with the mainshaft of the sewing machine.

Fig. 3 represents an enlarged sectional view taken substantially along the line 3-3, Fig. 2.

Fig. 4 represents an enlarged top plan View of the speed-responsive drive with certain Of the parts in section to illustrate more clearly the details thereof.

Fig. 5- is an enlarged elevational view of the trimmer-bar, the hearing support therefor, and the actuating toggle linkage for reciprocating said trimmer-bar.

Fig. 6 represents a sectional View taken longi tudinally of the trimmer-bar actuating toggle showing the spring detent'for maintaining the the toggle-links in their straightened position.

Fig. '7 represents an enlarged sectional view taken substantially along the line 'i-l, Fig. 5'. Fig. 8' represents an enlarged sectional view taken substantially along the line 88, Fig. 5. Fig. Qrepresents a sectional view similar tothe upper portion of Fig. 4, hut with the two weightsswung outwardly into a position such that the tails of the weight-carrying levers bias the beltpulley flanges a'partto reduce the pulleys efiS-ective diameter and thereby reduce the spe'edoi reciprocation of the'trimmer-knife.

Fig. 10 is an enlarged front elevational view, partly in section, of the trimmer loracketand the mechanism supported thereby, showing, in dotted lines, the manually controlled trimmer throw-out lever in its trimmer operating position, and, in full lines, the trimmer throw-out lever in an intermediate toggle breaking position.

Fig. 11 is a view similar to Fig. 10, but with the trimmer throw-out lever in its trimmer inoperative position with the trimmer knife latched in its raised or inoperative position.

Fig. 12 is a side elevational View of the togglelinkage taken in the direction of the arrow 12 in Fig. 11.

Referring to the drawings which illustrate a preferred embodiment of the present invention, the sewing machine has a frame including a basestandard as supporting the arm-standard 21 of a bracket-arm 22 terminating in a head 23 which overhangs an upright work-supporting post 2 1.

Journaled in the bracket-arm 22 is a horizontal 1nain-shaft 25 carrying at its rear end a combined beit-pulley and balance-wheel 25 adapted to be connected to any suitable power source by means of which the sewing machine is brought into and controlled as to its speed of operation. At its forward end the main-shaft 25 is connected in the usual way to a needle-carrying endwise reciprocatory needle-bar (not shown). During the stitching and feeding operations, the work is yieldingly depressed toward and into cooperation with a conventional feeding element 2'! operating through a throat-plate 27 provided on the work-supportin post 2d, by a roller-presser 28 carried on a spring-biased presser-bar Secured to a suitable boss 3% provided on the under side of the bracket-arm 22 is a trimmer bracket 3i having a verticall inclined portion thereof provided with vertically spaced bearing lugs 32 and 33 (Fig. The bearing- lugs 32 and 33 are provided with apertures which are alined in a vertically inclined direction, the upper bearing-lug 32 having a bearing-bushing 3 5, and the lower bearing-lug 33 a bearing bushing 35. Journaled for endwise reciprocation in the bearing-bushings 3d and 35 is a knife-carrier or -bar to the lower end of which a knife-holder plate 3? is adjustabl secured by a screw 38. Adjustably attached by screws 39 to the knife-holder plate 3? is the vertically slotted shank of a trimmer-kniie id provided with a cutting edge at. Cooperating with the trimmer-knife id in severing the work is a stationary ledger-blade 42 supported on the throat-plate 27. The trimmerknife G9 has a path of movement to sever the work substantially parallel to the line of seam formation, and the movement of the knife in a vertically inclined path transverse to the plane of the work results in the production of undercut trimmed edges. Accordingly, in the trimming of shoe linings, the trimmed edge of the lining is concealed by the beveled edge of the shoe upper, as is well understood in the art.

To facilitate in properly feeding the work to the trimmer-knife 66, there is provided the usual edge-guide 43 (Fig. 5) adjustabiy carried on a spring-depressed rod 8 3 endwise shiftable in the bearing- lugs 32 and 33 of the bracket 3i. The edge-guide 2-3 may be retained in its raised or inoperative position, as shown in Fig. 5, by a latch-lever 55, the spring d6 serving to bias the edge-guide downwardly into its operative position when the latch-lever is released.

To reciprocate the knife-bar 35, the latter has suitably secured thereto a collar i! having a fiat sided lateral extension 38 which is slidably disposed in a guide-slot 59 formed in a guide-block 53 integral with the trimmer-bracket 3|. The guide-block 53 functions to restrain the knifebar 35 against turning in its bearings, and the guide-slot is open at the lower end of the guideblock so that the slot may be adjusted as to width by means of a bolt ii to take up wear. Threaded into the end of the lateral extension 23 is a stud (Fig. (5), the conical body-portion of which is embraced by the lower end of a pair of interconnected toggle-links 53 and E4. The stud 52 is prevented from loosening accidentally in the lateral extension 2'8 by means of a screw 55 which 4 is adapted to draw together the split portions of the ex ension 38.

The toggle-links 53 and 5d are pivotally interconnected by a hollow knuckle-pin 55; the straightened position of the toggle-links 53 and 5 being determined by a stop-lip El integral wi h the upper end of the link 53 and adapted to engage the link To maintain the toggle-links 53 and 5-4 in straightened position, there is provided in the upper toggle-link 5d a detent in the form of a pin 58 (Fig. 6) biased by a coil-spring 59 into a suitable pin-receiving cavity 56 formed in the upper end of the lower toggle-link As will be seen in Figs. 4 and 6, the toggle-link Ed at its upper end is shaped to embrace a needlebearing iii mounted on a rotary actuator in the Torr. of an eccentric 62 preferably integral with a rotary shaft 63. The rotary shaft $3 is journaled in a needle-bearing 8d and a ball-bearing carried in the downwardly inclined pair of limbs 235, 8'5 of a substantially H-shaped supporting bracket 6 removably secured to a flat seat 59 (Fig. 2) milled on the back of the bracketarm The rotary shaft 53 is adapted to be driven by mechanism to be described later this specification. From the above description it will be understood that as the shaft $3 is rotated the eccentric through the straightened togglelinks 53 and will effect a reciprocation of the trimmer-bar in its bearings 3d and 35. The knife 45? carried by the trimmer-bar 35 thus is caused to cooperate with the stationary ledgermember 32 in severing the work presented to the trimmer-knife.

In machines of the present type it is frequently desirable to render the trimming mechanism inoperative and to that end manualy operable lever-means is provided for buckling or area..- ing the toggle link whereby the trimmerknife actuating means is disabled and the knife it? is raised to an inoperative or retracted position. The lever-means, in the present machine comprises a hand-1ever id pivoted at its upper end on a stud ll threaded into the limb of the bracket 58. The hand-lever id intermediate its ends is provided with an angular extension or limb l2 slotted adjacent its free end, as at 3, to form opposed abutment or side walls E i and 75 disposed to loosely straddle the extended end of the knuckle-pin 55 of the toggle-links 53, 5d. To provide for holding the trimmer-knife in its raised or retracted position as shown in Fig. 11, the angular extension '52 has pivoted thereto, as at it, a. latch i'l having an onset lower end affording a horizontal stop-ledge 18 adapted to cooperate with the trimmer-kniie carrier, and in the present case preferably with the projecting head it; of the toggle-stud 52. At its forward end the stop-ledge i8 is formed with a depending lip 3%. As viewed in Fig. 1, the latch ii is normally biased in a, counterclockwise direction by a spring @i into a position such that a trip-lug 82 on the latch it engages the lower edge of the hand-lever extension 72.

Consider now the operation of the hand-lever 19 in moving the toggle- links 53, 54 from a straightened position, in which they constitute a pitman for reciprocating the knife-bar 36 from the eccentric 52, to a broken pisition, in which the trimmer knife is inoperative. Referring to Fig. l, the trimmer-knife 46 is shown in its normal operative position; the hand-lever it) being retained in its illustrated position, with the side Walls M and '15 of the hand-lever extension 12 spaced from the knuckle-pin 56, by a spring catch. 83 seated in a suitable notch 84 formed in the upper end of the hand-lever Hi. When it is desired to render the trimmer-knife inoperative, the hand-lever I is manually swung from the position shown in Fig. 1 and in dotted lines in Fig. 10, to the position shown in Fig. 11. The sequence of operations caused by the swinging of the hand-lever is as follows: Manual pressure applied to the hand-lever IIl swings the same in a counterclockwise direction (Fig. 1) moving the side-wall I4 of the hand-lever extension I2 into contact with the knuckle-pin 53. Sufficient pressure applied on the hand-lever 'lli overcomes the resistance offered by the toggle detent 58, thus initially breaking the: teg 1elinks 53, As. the hand-lever IE3 continues to move the toggle-links are. further, broken, thus retracting the trimmer-bar 3.6 and moving the latch IT on the hand-lever extension i2 into a position, as shown in Fig. 10, in which position the depending lip 89 on they latch ii contacts the 12, with the stop-ledge T8 underlying the togglestud-head 19. Thus, the trimmer-bar 35 is latched in its fully retracted position with the knuckle-pin 53 disposed in spaced relation relative to the side-walls I4 and 75 of the hand-lever extension I2. With the trimmer-bar 3B securely held in retracted position, continued rotation of the eccentric -52 merely results in a slight. pivotal movement of the toggle- links 53, 54 about the axes of the stud 52, knuckle-pin, 56 and eccentric 52 without imparting any actuations whatever to the trimmer-bar 36. The absence of the customary spring means for retaining the trimmer-knife 49 in its inoperative position and the existence of clearance between the knuckle-pin- 56 and the side walls It and of the hand-lever extension I2 minimizes the load applied to the eccentric 62 during the operation of the machine with the trimmer-bar 3t retracted. The clearance between the knucklepin 56. and the extension 52 eliminates wear on the knuckle-pin 62 or side walls M and E5, and also permits the hand-lever It toremain stationary in the retracted position of the trimmer knife 48 (Fig. 11) or in the operative position of the trimmer-knife (Fig. 1)-. The spring catch 83 seated in the notch 84 maintains the handlever I0 stationary and in the position illustrated in Fig. 11.

The toggle-links 53-, 54 may" be moved into their straightened position and thereby sl-idably shift the trimmer-bar into the operative position thereof by actuation of the hand-lever it. Beginning with the parts. in the position shown in Fig, 11, movement of the hand-lever it about its fulcrum ll,- ina clockwise direction, will first move. the hand-lever extension 12 into contact with the trip-lug 82 after which continued movement of the; hand-lever 13 will force the latch lever 'i'l to pivot about it against the action of the spring 8I, thus. shifting the stop-ledge F8 from beneath the toggle-studi-head 1.9.. About the time the stop-ledge 78 has cleared the togglestudehead l9; the side wall I5 of the hand-lever extension l2 has moved into contact with the knuckle-pin, 56, and further movement of the hand-lever I0 effects a straightening of the toggle-links 53, 5A, thus depressing the trimmerbar 36. The normal straightened position of the toggle- links 53, 54 is determined by the stop-lip 51 on the toggle-link 53 engaging the toggle-link 54, the detent 58 serving to maintain said togglelinks 53 and 54 in their straightened position.

The preferred form of speed-responsive means for reciprocating the trimmer-bar 36 will now be described. Referring to Fig. 4, the rotary shaft 63, between its bearing supports 64 and 65, has. mounted thereon a belt-driven pulleyassembly, generally indicated as 85, the pulleyassembly including two separable flanges 86 and. 81 having opposed divergent side- walls 88 and 89 defining a belt-groove adapted to accommodate a V-belt at. The pulley-flange 86 is provided with a hub 9i which is fixed on the shaft 63 by a set-screw 92. The pulley-flange 81 has integral therewith an elongated hub 93 bored to slide endwise on the shaft (53 relative to the fixed pulley-flange 35. To prevent relative turning between the two pulley-flanges 86 and 8?, there is preferably provided a cylindrical locking pin 94 fixed at one end in the flange-hub .93 and having its other end slidably received in an aperture in the flange-hub 3|. The locking-pin 34 keys the two pulley flanges 86 and 87 together so that they rotate as one, but permits the pulleyflange 87 to shift lengthwise of the shaft 63 relative to the fixed pulley flange 86, whereby the effective pitch diameter of the pulleyassembly can be varied.

The \/-belt 33 derives its driving power from a second pulley-assembly 35 carried on a rotary shaft EEG journaied at one end in the ball-bearing 9? and at its other end in a needle-bearing 98, the ball-bearing and the needle-bearing being supported in the upwardly inclined limbs t9 and I05 of the H-shaped supporting bracket 68. The shaft 95 at its inner end is driven through the bevel gears lei, m2 (Fig. 2) by the arm-shaft 25 of the machine. lhe pulley-assembly 95, like the pu1leyassembly 35, comprises two separable flanges ids and Mi having opposed divergent side walls Hi5 and H76 defining a belt-groove for the V-belt 96. As shown in Figs. 4 and 9 the pulley-flange 533 is provided with a hub E57 secured to the shaft 96 by the set-screws I08. The pulley-flange I84 is formed with a hub I09 bored to slide lengthwise of the shaft 95 toward and away from the fixed pulley-flange I83. To prevent relative rotation between the pulley-flanges I83 and i5 1, the hub iii? of the pulley-flange 63 has pressed into it a locking pin H0 having its projecting end slidingly disposed in a hole II I (Fig. 9) drilled in the hub I529 of the pulleyiiange Hi l.

It will be understood from the above description that power to drive the endwise reciprocating trimmer-bar 35 is obtained from the rotary arm-shaft 25 of the sewing machine and that the power is transmitted from the rotary shaft 96 which is geared to the arm-shaft through the pulley-and-belt drive to the rotary shaft 63, the eccentric $52 on the shaft 63 reciprocating the trimmer-bar 55 through the toggle-links 53 and 5d when they are in their straightened position. When the sewing machine is operating at slow speed, i. e. of the order of below approximately 1090 stitches per minute, the component parts of the speed-responsive drive are in the position shown in Fig. 4. When in this position, it will be seen thatthe effective diameter of the pulley-assembly 35 is greater each of the arms is formed with a than the effective diameter of the pulley-assembly 85, resulting in a frequency of reciprocation of the trimmer-bar 36 of about twice that of the sewing needle.

To effect a decrease in the number of reciprocations of the trimmerbar 35 as the speed of the machine increases, there is provided a speedresponsive governor mounted on the rotary shaft 96 adjacent the pulley-assembly 95. The governor, as shown in Figs. 2, 4 and 9, comprises a collar H2 fixed on the shaft 96 by a set screw I IS, the collar II2 having at one end a cylindrical head or flange lid. The collar-flange M4 is provided with two diametrically arranged slots H5 each opening at its outer end in the periphery of the collar-flange H4 and at its inner end in a counterbore Iii: coaxial with the shaft-bore in the collar H2. Disposed in the slots I55 are two bell-crank arms I I7 fulcrumed on the transverse pivot-pins H8 pressed into the collarflange IE4. Each of the arms is weighted at its outer end, as indicated at IIB. At its inner ends, tail I29 adapted to engage the outer face of a thrustwasher I23 (Figs. 4 and 9) mounted on and slidable longitudinally of the rotary shaft 96. The inner face of the thrust-washer 52! contacts the ends of four thrust-pins I22 endwise slidable as shown in Figs. 3 and 9 in alined apertures formed in the collar H2 and the pulley-flange hub IN, the other ends of the four thrust-pins bearing upon the inner face I23 of the pulleyflange-hub ISQ. The two bell-crank arms Ill are normally biased into a collapsed or closed position, as shown in l, by two coil-sprin s I25 disposed on opposite sides of the rotary shaft 96 and connected at their opposite ends to spacer-pins i255 passing through the body of each of the bell-crank arms II'I.

When the speed of rotation of the shaft 95 exceeds a certain amount, centrifugal force causes the bell-crank arms II"! to swing about their pivots H3 into an open position, such as illustrated in Fig. 9. In moving from closed position to open position, the tails I29 of the two bell-crank levers ill acting on the thrustwasher lZI shift the thrust-pins I22 endwise. cause the movable pulley-flange ltd to separate from the fixed pulley-flange Hi3. This separation of the two pulley-flanges I83, mil increases the width of the V-belt groove defined by the divergent faces IE5 and I66, thus permitting the belt 9i? to move closer towards the axis of rotation of the pulley-assembly es, whereby the effective diameter of the pulley-assembly is decreased.

To effect a simultaneous increase in the ef fective diameter of the pulley-assembly when the effective diameter of the pulley-assembly is automatically decreased, a linkage is provided which connects the movable flange-member of the pulley-assembly -95 to the movable flangemember of the pulley-assembly 85. Referring to Fig. 4, the extended hub Hi9 of the pulley-flange 6 2 is reduced to accommodate a thrust-bearing I23 which is engaged by the bifurcated upper end of a lever 52? iulcrumed at I28 on the supporting bracket 38. The lower end of the lever 22? is shaped to receive one end of a two-piece extensible push-rod I29, the other end of which rides in a seat provided in the upper end of a second l ver I38 fulcrumed at I35 on the supporting bracket es. At its lower end the lever I38 is bifurcated to straddle the rotary shaft 53 and bear against a thrust-bearing I 32 mounted on the reduced portion of the pulley-fiange-hub 8's. A coil-spring I33 connected at one end to the upper end of the lever I30 and at its other end to an eye I33 on the bracket 68 normally biases the pulley assemblies and into the position shown in Fig. 4, which is the position occupied by these parts during low speed operation of the sewing machine. A suitable belttightener is provided for taking up slack in the belt Qt and, in its preferred form (Fig. 1), comprises a belt-engaging wheel I35 freely journaled on the lower end of a flat sided rod I36 adjustably clamped by a set-screw I37 in the supporting bracket 68.

Referring to Fig. 4, it will be understood that the coil-spring I33 normally biases the flangesections I93 and I04 of the pulley-assembly 95 into their closed position, in which position the efiective diameter of the pulley-assembly 95 is at a maximum. Since the length of the belt 99 is fixed, the tension thereon, as it runs on the pulley-assembly 85, is sufiicient to force the belt towards the axis of the shaft 63 and, in so doing, the flange-sections 86 and 81 of the pulleyassembly 85 are urged into their separated relation, which is determined by the position of the lever I30, and which position can be regulated by adjustment of the length of the push-rod i29. As previously indicated, the tension of the coil-spring I 33 is sufiicient to maintain the pulleyassemblies in the positions shown in Fig. 4 during low speed operation of the machine. When the speed of the machine is increased beyond a certain extent, the weighted arms II! of the speedresponsive device swing outwardly in response to centrifugal force into a position shown in Fig. 9. When this occurs, the tails I20 of the weighted arms II'I move inwardly against the thrustwasher I2I causing it to engage and shift the four thrust-pins I22 against the inner face of the pulley-flange-hub I01, thus forcing the pulley-flange I04 to separate from the fixed pulley-flange I03. This movement of the pulleyflange I64, through the thrust-bearing I26, lever I21 and push-rod I29, swings the lever I30 in a counterclockwise direction (Fig. 4) so that its bifurcated lower end bears heavily against the thrust-bearing I32 and forces the pulley flange 87 toward the pulley-flange 86, thus increasing its effective diameter.

From the above it will be seen that an increase in speed beyond a predetermined amount will result in a simultaneous change in the effective diameters of the two pulley-assemblies B5 and. 95, the change in diameters being of a character to decrease the ratio of the relative frequencies of the trimmer and stitching mechanisms.

Having thus set forth the nature of the invention, what I claim herein is:

1. In a sewing machine having stitch-forming mechanism including a movable needle, actuating mechanism for operating said needle, a trimmer associated with said stitch-forming mecha nism including a movable knife, actuating mechanism for operating said knife, and a device rendered effective by centrifugal force and included in one of said actuating mechanisms for automatically controlling the frequency of movement of one of said movable members.

2. In a sewing machine having stitch-forming mechanism including a movable needle, actuating mechanism for operating said needle, a trimmer associated with said stitch-forming mechanism including a movable knife, actuating mecha- :3 nism for operating said knife, and a device responsive to centrifugal force included in one of said actuating mechanismsfor automatically decreasing the frequency of movement of one of said movable members as the frequency of movement of said other movable member is increased.

3. In a sewing machine having stitch-forming mechanism including a reciprocatory needle, mechanism including a rotary shaft for actuating said needle, a trimmer associated with said stitch-forming mechanism including a reciproeating knife, actuating mechanism connected to said rotary shaft for reciprocating said knife, and a device operated by centrifugal force and associated with said trimmer actuating mechanism for varying the frequency of reciprocation of said knife with respect to said needle.

4. In a sewing machine having a frame, stitchforming mechanism including a reciprocatory needle, mechanism including an actuating shaft for reciprocating said needle, a trimmer associated with said stitch-forming mechanism including a reciprocatory knife, and mechanism for actuating said knife, said last-named mechanism including spaced rotary shafts, a variable diameter pulley-assembly mounted on each of said rotary shafts, a belt connecting said pulleyassemblies together, and means including a speed responsive device mounted on one of said rotary shafts for varying the size of each of said pulleyassemblies.

5. In a sewing machine having a frame, stitchforming mechanism including a reciprocatory needle. a rotary shaft journaled in said frame and operatively connected to reciprocate said needle, a trimmer mechanism supported by said frame and including a movable knife adapted to operate adjacent said needle, and operative connections for actuating said knife, said operative connections including a first shaft driven by said rotary shaft, a second shaft spaced from said first shaft, variable diameter pulley-assemblies mounted on said first and s cond shafts, a belt connecting said pulley-assemblies, and means responsive to centrifugal force for varying the diameters of the respective pulley-assemblies to change the frequency of movement of the trimmer-knife with respect to that of said needle.

6. In a trimming having a frame, a rotary shaft journaied in said frame, trimmer mechanism supported by said frame and including a movable knife, means connecting said movable knife to said rotary shaft, and speed-responsive means rendered effective by the speed of rotation of said rotary shaft for varying the frequency of movement of said movable knife inversely to the speed of rotation of said rotary shaft.

'7. In a trimming machine having a frame including a work-support, feeding means for advaneing work through the machine, a movable work-severing knife, and means for moving said knife including a rotary device responsive to centrifugal force for varyin the frequency of movement of said knife relative to the work-advancing speed of said feeding means.

8. In a trimming machine having a frame including a work-support, feeding means for advancing work through the machine, a movable work-severing knife, and means for moving said knife including a rotary device responsive to centrifugal force for effecting a decrease in the relative speed ratio of the movable knife and the feeding means during an increase in the workadvancing speed of said feeding means.

9 In a trimming machine having a frame including a work-supporafeeding means for ad-' vancing Work through the machine, a movable work-severing knife, and means for moving said knife, said means including spaced rotary shafts, variable diameter pulley-assemblies mounted on said shafts, a belt connecting said pulley-assemblies, a speed-responsive device mounted on one of said shafts and effective for varying the diameter of one of said pulley-assemblies, and means interconnecting said pulley-assemblies and rendered effective by the changing of said pulleyassembly for simultaneously producing a change in the diameter of the other of said pulleyassemblies.

II). In a trimming machine having a frame including a work-support, a movable Work-severing knife, and means for moving said knife, said means including spaced rotary shafts, variable diameter .pulley-assembiies mounted on said shafts and including'relatively separable flangesections, a beltconnecting said pulley-assemblies, means on one o'fsaid rotary shafts responsive to I centrifugal force for effecting a separation'of the flange sections of one of. said pulley-assemblies, and means actuated by the separation of said pulley fian'ge-sec'tionsfoi' causing a relative approach of the flange-sections of said other pulleyassembly.

11. In a trimming machine having a frame including a work-support, a movable work-severing knife, and means for moving said knife, said means including spaced rotary shafts, a variable diameter pulley-assembly mounted on each of said shafts and including relatively separable fiange-sections, a belt connecting said pulleyassemblies, a linkage interconnecting said pulleyassemblies, a spring acting on said linkage for biasing the flange-sections of one of said pulleyassemblies into a closed position and the flangesections of said other pulley assembly into an open position, and means on one of said rotary shafts responsive to centrifugal force for overcoming the force of said spring and causing a reversal in the flange positions of said pulleyassemblies.

12. In a trimming machine, in combination, a work-advancing feeding-element and a movable trimmer-element operable at a variable ratio of relative frequencies, means for actuating said feeding-element, means for moving said trimmerelement, and means for varying said ratio including a rotary device responsive to centrifugal force for operating said trimmer-element at different speeds.

13. In a trimming machine, an actuating element, a movable trimmer-knife carrier, connections for actuating said carrier from said ele-' ment including a pair of toggle-links relatively movable into and out of toggle-straightened operative position, a manually controlled levermember for straightening and for buckling said toggle-links, and a latch-device carried on said lever-member for maintaining said toggle-links in their buckled position.

14. In a trimming machine, an actuating element, a movable trimmer-knife carrier, connections for actuating said carrier from said element including a pair of toggle-links relatively mo'vable into and out of toggle-straightened operative position, a manually controlled lever-member op- .erable for straightening and for buckling said toggle-links, and a latch-device carried on said lever-member and disposed to cooperate with said carrier in maintaining said toggle-links in their buckled position.

15. In a trimmin machine, an actuating element, a movable trimmer-knife carrier, connections for actuating said carrier from said element including a pair of toggle-links relatively movable into and out of toggle-straightened operative position, a manually controlled lever-member operable for straightening and for buckling said toggle-links, and a latch-device for maintaining said toggle-links in their buckled position, said latch-device having a stop-ledge disposed to underlie a projection on said trimmer-knife carrier when the latter is in its retracted position.

16. In a trimming machine, an actuating element, a movable trimmer-knife carrier, connections for actuatin said carrier from said element including a pair of toggle links relatively movable into and out of toggle-straightened operative position, a knuckle-pin having a portion extending beyond said toggle-links, a single manually controlled hand-lever having spaced abutment walls disposed on opposite sides of the extended portion of said knuckle-pin whereby movement of said hand-lever in opposite directions will straighten and buckle said toggle-links, and releasable means for locking said toggle-links in straightened and buckled positions thereof,

17. In a trimming machine, an actuating ele REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 498,617 Borton May 30, 1893 2,323,750 Frey July 6, 1943

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