US2570660A - Transfer mechanism - Google Patents

Description

Oct. 9, 1951 R. M. GAMBLE TRANSFER MECHANISM 7 Sheets-Sheet 1 Filed April 6, 1945 1 02 ZzZj% MZ MWzZ/ TRANSFER MECHANISM Filed April 6, 1945 '7 Sheets-Sheet 2 R. M. GAMBLE TRANSFER MECHANISM Oct. 9, 1951 7 Sheets-Sheet 5 Filed April 6, 1945 Oct. 9, 1951 R. M. GAMBLE TRANSFER MECHANISM '7 Sheets-Sheet 4 Filed April. 6, 1945 R. M. GAMBLE TRANSFER MECHANISM Oct. 9, 1951 7 Sheets-Sheet 5 Filed April 6, 1945 Oct. 9, 1951 R. M. GAMBLE TRANSFER MECHANISM 7 Sheets-Sheet 6 Filed April 6, 1945 EEYkEan z WY?! Oct. 9, 1951 R. M. GAMBLE TRANSFER MECHANISM Filed April 6, 1945 7 She et sSheet 7 eing m ve to a de ivers: s atics, Wh le he set:

Patented Oct. 9, 1951 UNITED STATES PATENT OFF ICE 2,570,660 1 5.43%?! G I N 'SM Ralph M. Gamble, Springfield, Vt., assignor to Jones & Lam'soii Machine Company, Spring field, Vt a corporation of Vermont Application April6, 1945, Serial No. 586,935

'eclaims. (o1. 2 141 is heine' e eh it m time? sta ieni t," e'

. 3? v et work piece removed from the tooling stat nd k ie e s in test d it m. the. hhh y t n o he too in s ation. The m chan m then retires tov an intermediate positiQn out of the way whe t r ma ns d e tool n operai on he w rk hieee resumes at he teh i s station, k

A rther obj ct of he iii-tenths s t rov d u h nism we l adapted to, he, carried by an automatic machine tool sugh, as, a lathe, and to be a uat d. bi; m ch ne contro me h nism a t m el v n me. wit the o erative y e of e m h ne, o l. If de ired. els the s r h ni m me be mad te Positi el grip the work, the work bein automatie ny e? leased atsuitable times in the c an,

A further object of the invention to provide for accurate positioning of the work piece, par-t ticularly at the toolingstation, and for manila: ulation of the work holding means at-the tooling station in proper timed relation to the actuation of the transfer mechanism, a

For a complete understanding of this invene tion, reference may be had to. the accompanying drawings in W iQ I i re 1 is. a f a me tar tmht el s ieh of an automatic lathe of the well known Faytype showing the mechanism embodying the invention applied thereto.

Figure la is a fragmentary view partly in sec.- tion showing the work hold-hack for the tail:

tock, wh h is also sh wn a smel s? scale and in a different position in Figure; 1

Fi e 2 is a fr gmentar rea ele tion of the same.

ure 3 i end lev ti n t the mec ani m certain of t e the ar s bein shew in r l tihn thereto. f

Figure s a rs ect e. iew or ork, iece en ag ng el men of. the mec nism su 5 is a. v e simi a s a her ie Lei Fi ur 3 but to a larg scale, nd with est te P rts be n s own. n section.

Figure 6 a View this? ts her semen but ts a lair-set ens omitting ce n dotteq l s empty conditions, respectively.

Figure 13 is a sectional view on line l3+liiv of Fi ure 9.

Figure 14 is an exploded isometric view of oer? thin o the parts hewh in Figure Figure 15 is an end elevation of a work transfer arm provided withv a work gripper in opera: tive relation to a work holding spindle.

Figure 16 is a fragmentary view partly in elevation and partly in section showing the work centers and the transfer mechanism in position o e a e a WQrk piece of a diffeernt type tha shown in Figure 9 between the centers.

Figures 17 and 18 are detail sectional views, on ines Il'-l 1 nd i i-18 r pe ti e o Fi ur 16.

Figure 12 is a perspective View of a work piece els h wn Fi r 6-.

Figure 2.0 is a View similar to Figure 11, but to a larger scale and. showing a modif ed construction, the chuch being closed onto the work shown n br ken. ines.

Figure 21 is a sectional view on line 2l -2| of Figur 2.0-

Figure 22 is a detail sectional view on line Z 2 Of i u 2Q- Figure 23 is a detail section on line 2 323 of Figure 21, but showin the chuck jaw open.

Figure 24 is, a View similar to Figure 2 3, but showing the chuck jaw closed and the. chuck empty.

Figures 25, 2 6 and 27 are fragmentary views partly in, elevation and party in section showing the relationship between a work-gripping jaw and its opening member, corresponding to, the jaw positions of Figures 20,, 23 and 2?, respective y,

Referring to, Figures 1 to 8, the subject matter of this invention is shown as applied to a lathe of the. well known Fay type. This lathe comprises a former cam 9. This former cam is moved generally lengthwise of the machine, and if desired in an inclined directioni by suitable cams carried by a cam drum l0. This cam drum l and sec 0nd and third cam drums I I and l2 secured to a common cam drum shaft determine the cycle of operations of the machine. The tool bar 5 carries the back tool arm l5 provided with one or more tools at l6. This arm I5 is also controlled by a former cam |5a (Figure 2) somewhat similar to the former cam 9 at the back of the machine. This is the standard construction of the well known Fay lathe.

For the purpose of the present invention, the

headstock 2 has mounted thereon a support 20 to which a bracket 2| is attached. This bracket 2| has fixed thereto a pivot member 22 on which is journaled a pair of blocks 23 and 24. These blocks 23 and 24 form parts of a pair of transfer arms, each arm comprising a pair of parallel bars 25 and 26 spaced on opposite sides of the pivot 22 and slidable through their respective blocks 23 or 24. The bars 25 and 2B are connected together at their end portions by the cross members 21 and 28, and as best shown in Figure 6, the cross members 2'! at the upper ends of the pairs of bars have, between the bars 25 and 26, threaded stops 29 which may be fixed in adjusted position as by means of set screws 30.

These stops 29, when they engage against the blocks 23 or 24, determine the limits to which the arms may be extended from the pivot 22 and thus determine the final extended positions of these arms when a work engaging element 3| carried by each end member 28 is positioned to present the work into the tooling position between the centers 35 and, 36 of the head and tailstocks or into the extreme supply or delivery positions. The tailstock center 36 is mounted for axial motion in order to free the work piece from between the centers when desired, this being accomplished by the rocking of a lever 40 pivoted at 4| on the front face of the machine, the upper end of this lever operatively engaging a slide 42 in the well known manner which carries the tailstock center 36. One ejector rod 43a for the center is normally held retracted therefrom as by means of a spring 43. The lower end of the lever 40 is connected through a link 44 to a slide 45 actuated by cams on the cam drum l2 by which the tailstock center is retracted and advanced at suitable times in the automatic cycle of the machine.

The headstock spindle is also provided with work-ejecting means movable in time with the retraction and advancement of the tailstock center, one such means being shown in Figures 9 to 14, inclusive, the ejector 50 engaging the end of the work piece 5| and being movable axially of the center 35 by axial motion of a rod 52 which extends entirely through the headstock and is actuated by the rocking of a lever 55 fulcrumed on a fixed pivot 56. The upper end of this lever 55 carries a member 58 which engages the outer end of the ejector rod 51 and the lower end of the lever 55 extends down into the operative relation to suitable cams on the drum II by which the lever 55 may be oscillated in proper timed relation in the machine cycle. The head and tailstock centers define between them a tooling station for the work pieces.

A work piece 5| may be held against. retraction all the way with the tailstock center by a bracket 400 having a hole through which the dead center may project and carried by a spring pressed 4 plunger 40| slidable within a casing 402 secured to the slide 42. When the tailstock is in its projected position shown in Figure 1, the tailstock center projects through the hole in the bracket 400 and into engagement with the work piece, and the head 403 of the plunger MM is out of contact with the tailstock. As the tailstock slide isretracted, the head 403 of the plunger contacts the tailstock and stops retraction of the bracket 400 as shown in Figure 1a, while the tailstock slide continues to retract to the dotted line position with its center retracted from the forward face of the bracket 400. This allows the work to be ejected from the headstock spindle as far as the bracket,

the hole in the bracket through which the dead center extends being too small to pas the work piece. 'Thus after the work piece has been engaged by the transfer arm, as will later appear, the ejector frees the work from the headstock center and the bracket 400 insures the separation of the work piece from the tailstock center so that the work piece is free to be removed by the trans fer mechanism and another work piece placed in position between the centers. The tailstock center may then be advanced to engage the work piece and then move it axially, while retracting the ejector, into engagement with the headstock center ready for a succeeding machining opera-. tion.

One of the work transferring arms compris ing a pair .of rods 25 and 26 shown in Figures 1 to 6, inclusive, as the one nearest to the bracket 2|, is arranged to take the" work pieces one by one" from the tooling station and move them to a delivery station at 60, while'the other transfer arm is adapted to move between the tooling station and a work supply station 6 I to transfer work pieces one by onefrom the supply station to the tooling station. 7

The work piece 5| is shown as a cylindrical piecejprovided with a hole therethrough, this cy= lindrical piece being adapted to be gripped at the headstock in thetooling station as shown in Figures 10 and 11 by a pair of gripping jaws 65 hav ing gripping surfaces 66 eccentric to the pivots 61 about which the jaws 65 are turnable. These jaws are normally urged toward the gripping position shown in Figure 10 with the jaw portions 06 engaging the work piece 5| as by spring pressed plugs 68. V V

The ejector 50 as shown best in Figure 14, has an enlarged diameter portion 10 provided with a pair of angularly disposed slots 'I| within which ride pins 12 projecting inwardly from a sleeve 13 within'which the portion 10 is axially slidable, The forward end of the sleeve 13 is provided with a pair of arcuate fingers 14 which are adapted to extend between the jaws'65 and to be rockableabout the axis of the ejector rod 52 between the positions shown in Figures l0, l1 and 12. In Figure 10, these fingers 14 are out of contact with the jaws 65 and permit the jaws to grip the work piece. By rocking the sleeve 13 in counterclockwise direction from the position shown in Figure 10 to that, shown in Figure 11, the fingers 14 engage the jaws 65 and retract them, freeingthe work piece, the jaws then being open as shown in Figure 11. In Figure 12 the sleeve 14' has been returned to the angular position of Figure. 10 which allows the jaws 65 to take the position shown therein in case no work piece is positioned between them. This rocking action of the sleeve 13 is occasioned by the relative axial motion between the portion 10 and the sleeve 13, and when the workhas been 5 released, forwardaxial motion of the rod. 52' pushesthe ejector 50 forward and ejects the 51 from. the headstock" center' 35, this be.- ing done in time with the retraction of the tai1- stock center so that the work isfreed frombotln This ejection of the work causes. the work, to. be moved axially, and this. is done while. the work.- engagingmember 3|: of the transfer arm which is to remove the work piece from the tooling station and transfer it: to: the: delivery station is in engagement therewith.

As shown in Figure.- 4, this work-engaging member 3I' comprises: a pair of spring jaws 80 having curved portions BI: adapted to; embrace the Work and flaring end portions 82, which when pressed against the. work, cause. the jaws to be sprung apart. to permit the. work to enter between the curved" portions 8|. These spring po1ttions 80 are secured to a block 83 positioned fiierebetween, which, in turn, is secured to. the end piece 20 of each of the transfer arms.

The: reverse motion of the head and tailstock centers by which the. tailstock center is advanced to contact a work piece and force the work piece onto the. headstock center while; the ejector is in retracted position is. accomplished while the work-engaging element. 5| of that arm which is moved to transfer the work pieces one by one from the supply station to the tooling station is at the tooling station, the work sliding through the. work holding member 31 but: in. the reverse direction to. that. when the. work piece is to be removed from the tooling stations In Figures 3: and 5' a supply station is illustrated, comprising a. suitable hopper I having a bottom wall, I-0I sloping downwardly and an end wall E02 spaced therefrom. at. a distance such as to permit a single layer ofworkpieces only to pass between the two. The lowest of these work pieces in this layer comes; to rest against a dog I03; pivoted at I04 to the bottom wall I 0! and normally held in position to obstruct the. free passage of the work pieces as by a spring pressed plug 05 which engages its. under side; A second dog I06 is fulcrumed at I01 on an extension I08 from the wall I02 and is provided with a downwardly projecting hump I09. This hump I09 is adapted to be contactedv by the end wall 28 of one of the transfer arms and to be rocked upwardly as shown. in full lines in Figure 5 out of obstructing relation to the lowest work piece 51 in. the single layer which has passed beneath the end wall I02. This permits the work-engaging member of the transfer arm to be pushed over this lowest work piece so that when this arm is retracted therefrom, it carries. the lowest. work piece therewith, causing the dog I03 tobe depressed against. the action of the plug I05 tofree the last work piece from the delivery station, while the dog I06 drops back into position to hold back the next work piece until such time as the dog I103 has been permitted to return to its obstructing position.

The transfer arm is then. moved axially and about the pivot 22 to present the. Work into the loading position. This is accomplished by the swinging of a lever II5 pivoted to the end plate a. guide bar I24. and; controlled; by s itable.- cams on the cam drum I0. I

like other transfer arm is at: the same tim moved from a..- nosition where its. worhe rieag ng member 31I engages a. workpiece. at; the. toolin station. to the delivery station 60. This; ac;- complished; by the swinging of an arm 2 criuned at I20: on a fixed frame member I21, which. also carries, the. pivot II'IS, this. arm. I25 being actuated. by the same. link [[3 through an arm I228. of the bell. crank lever II! which; is connected through an adjustable link" I219 to, an

' arm I30 connected to the. arm. I215.

The. delivery station, comprisesv means for stripping a work: piece. fromv the work-engaging elememt; 3.1. This consists of a base member I;3.5 secured to a portion. of the bracket 2I and; having: a. lower wall member I 36. onto which the ork piece is. presented by the transfer arm. A pivoted dog i 31 supported above the Workpiece yields to permit the. work: piece to be pushed therepast and then falls. down back of it in the position show-n Figure 3, with its; lower end enga n the: work piece, its upper end at I58 being pressed against a. stop member E39 of the stripper which prevents the dog from counterclockwise rotation from the position shown in Figure 3, so that when the member 3.I' is. retracted it forcibly moves the Work piece out. from between the work piece jaws. The work thus freed rolls down the support I36, and falls; into a. suitable receptacle I40. beneath it; as shown in Figure 3.

During the tooling operation performed on, the work at. the tooling station, the transfer arms are moved to positions of rest between the end positions and out of contact with the work, such posittions of rest being shown in dotted lines in Figure 3, the arm for transferring the work from the tooling station to the. delivery station beingshown as substantially vertical, and the arm for delivering from the supply station to the toolingstation being shown substantially horizontal.

In Figure 7 a modification isv shown in which the supply and delivery stations are on opposite sides of the tooling station from that shown in Figure 3, the forward transfer arm then taking the work piece from the receiving station I and transferring it to the. tooling station while a workpiece at the tooling station is transferred therefrom to the delivery station at I5'I. The receiving station I50 as shown in Figures '7 and 8., comprises a chute in which a single layer of work pieces may r011 toward its mouth, the lowest of the Work pieces in the chute being normally stopped by a dog I52 fulcrumed at I53 and pressed upward by a leaf spring I54 into position to receive the lowest work piece in a depression I55 therein, a stop pin I55 limiting the upward movement of the dog I52. Above this dog I52 is pivoted at I51 a second dog I58, the lower end portion I50 of which is h ld by gravity in obstructing relation to. the lowest work piece held in the depression I55 of the dog I52. A stop pin I limits this downward limit. of motion. The dog I58 is. provided with a projection I6I adapted to be contacted by the end member 20 of the transfer arm and to be rocked up thereby o that the work-engaging elementv 3| may grasp the lowest work piece. Then by outward motion of the element 3i, this work piece is removed from the dog I52, the dog I58 droppin as. the transfer arm leaves to prevent the release of the next. work piece which then takes its position as the. lowest work piece at the station when the dog I52 springs upwardly into the position shown in Figure 8.

The delivery station l! shown in Figure '7 comprises a chute for a single layer of work pieces at I65 inclined downwardly with its upper end adapted to be normally somewhat obstructed by a dog I66. This dog !66 is gravity pressed against a stop pin I6! in such position that after it has been lifted by the introduction of a work piece beneath it into the chute I65, and drops into the obstructing position shown it prevents the removal of the work piece by the transfer arm on retraction of the transfer arm therefrom. I

In some cases it may be found desirable to firmly grip the work while it is being trans ferred, locking it from accidental lateral displacement from the work-engaging portions of the transfer mechanism. Such a construction is shown in Figures to 17, and a work piece of a somewhat different form than that previously described, and which may be handied by such mechanism, is shown in Figure 19. Only one of the transfer arms is illustrated in these figures, but it should be understood that two arms of identical construction would be employed. In place of the spring jaws previously described, the work-engaging part of the transfer arm comprises a head this head having sockets to receive the ends of the bars and 26 which are secured therein as by the pins 20!. The head 200 is provided with a pair of spaced side plates 203 between which are pivoted on the pivots 204, a pair of jaws 205. The upper portions of these jaws above the pivots 204 are formed on their adjacent edges with tapered walls 206 which may be engaged by the outer faces of a pair of spring pressed plungers 201. Each of these plungers has an enlarged diameter portion 208 mounted for sliding motion through openings in one of the side plates 203, the other side plate having bushings 209 seated in the correspondingopenings and forming guides for reduced diameter shank portions 2! of the plungers 201. These reduced diameter portions extend through enlarged diameter sockets 2!! in the bushings 209 and are normally pressed axially into the position shown in Figure 17 by coil springs 2l2 surrounding these shanks and reacting between the bases of the sockets I20 and heads 2 l4 pinned to the end portions of the shanks. shown in Figure 1'? with the enlarged diameter portions 208 of the plungers located between the jaws 205, the lower ends of these jaws are pressed toward each other in the position shown in Figure 18 to close about the work. The outer faces of the upper end portions of the jaws may engage stop pins 2l5 which limit the closed positions of the jaws. Above the stop pins a spring 2!! is housed within telescopicaly related casing members H8 and H9 which engage upward extremities of the jaws and tend to hold them in closed position. The end plates 203 are provided with serrated edge portions 220 which coact with widened extremities 22! of the jaws to engage the work and hold it firmly.

At each of the stations where the work is to be released is positioned a cam plate 225 (see Figure 16), such a plate being shown at the tooling station and having a hole for the passage of the retractible tailstock center 226. This plate 225 is so related to the transfer arms that when these arms are brought into the corresponding position, the cam plate 225 engages against the caps 2!4 of the plungers and pushes these plungers inwardly, bringing the smaller diameter por- In the position 0 tions of the shanks 2l0 opposite to the jaws 205, thus releasing these jaws so that their lower ends may b swung outwardly when subjected to pressure from the work, as it is when placed or removed from between the jaws. A work piece which may be held by the jaws 205 is shown in Figure 19 and comprises a cylindrical portion 230, provided at one end with a head 23! extending diametrically outwardly from the portion 230, The portion 230 is arranged to be held by the gripping arms 205 and to be slid axially thereof by the action of the tailstock center when it moves forwardly and presses the work piece against th headstock center 235 in the position shown in Figure 16.

For machining purposes, the headstock spindle chuck 235 is shown as provided with a pairof driving dogs 236 having flat face portions 23'! for engagement with the sides of the extensions 23! of the work piece. The work may be ejected from the headstock center when the tailstock center is retracted, by spring pressed ejector plugs 24!] carried by th chuck and engaging the adjacent end face of the work. Each plug may be removably secured in the chuck 235 by a set screw 24! having a reduced extremity with. which the plug slidably engages through a slot 242 in the plug.

When work pieces of the type shown in Figure 19 are to be machined, it is desirable that the work spindle be stationary in a predetermined angular position when work pieces are being removed and replaced but as mechanism for accomplishing this forms no part of the present invention it has not been illustrated herein.

In Figures 20 to 2'? is shown work gripping and eject ng mechanism of a type somewhat modified from the construction shown in Figures 10 to 14. Referring first to Figure 21, at 250 is shown the nose of the spindle to which is secured a chuck comprising a body 25!, this body being secured to the spindle nose as by the screws 252 shown in Figure 20. The forward face of the body 25! is recessed as at 25'! and within the recess are pivoted a pair of work-engaging jaws 253, screws 254 forming the pivots for these jaws. Each of the jaws has a serrated work-engaging face 255 eccentric to its pivot 254 and the jaws are nor mally held toward closed angular positions by means of a pair of spring pressed plugs 256 seated in sockets in the body 25! and bearing against one edge of each of the jaws 253. Centrally of the body it is provided with a tapered hole 258 for the reception of a headstock center 259, the outer end of which is formed to engage within the central'bore of the work piece 5! shown in broken lines in Figure 21.

The forward end of the center 259 extends into a deepened portion of the recess 25! and within this deepened portion is positioned a work ejector 260 which has a hol therethro-ugh, as shown in Figure 22, through which the center 259 projects, so that the ejector is in a position to impinge upon the end of the work piece and by outward motion exerted thereon eject it from engagement with the center 259. In order to produce this ejecting motion, the ejector 260 is provided with a pair of rods 26! (see Figure 20), each of which is formed as a headed screw threaded through holes 262 in the ejector and extending slidably through holes 253 through the body, the heads 264 of these screws riding within a recess 265 in the back face of the body and provided with extensions 266' into which the heads 264 may be pressed. In line with the heads 264 is an actuating member 279 which, as shown, is a circular plate having a rearwardly extended hub 211 into which the forward end of an actuating rod 272 is threaded. This rod extends through the head stock of the machine and takes the plac of the bar 51 shown in Figure 1. secured therein a pair of forwardly extending rods 214 slidable through holes through the head 25] and parallel to the rods 255 of the ejector and to the axis of the work. These rods 214 are provided with reduced rear extremities riveted over in holes 2'55 through the actuator 215. Their forward ends are formed frusto conical as at 216 and cooperate with mating faces of a pair of plugs 211' projecting from the rear faces of the jaws 253.

When the actuator 275 is in its fully retracted position shown in Figure 21, the rods 274 are retracted and engage the jaw plugs 21! in the position shown in Figures 24 and 27 when the chuck is empty. When a Work piece is between the jaws, the gripping faces are somewhat more widely spaced, depending in amount upon the precise diameter of the work piece, the parts'then being in the positions in Figures 23 and 25, the

jaws being rocked somewhat toward open position with their plugs 27? out of contact with the chuck-opening rods 214. 7

When a work piece is to be ejected, .the actuator 210 is moved to the right as shown in Figures :1:

21 and 22, this action projecting the rod 214 and causing their cone faces to contact with the cone faces of the corresponding jaws and to wedge the jaws apart to their open positions,

one jaw being shown in that position in Figure 23 and its rod 214 in the dotted line position of Figure 26. When the jaws have been moved to fully open position, but While the actuator 21!! The actuator 270 has is still back from its extreme forward position,

it contacts with the heads 264 of the ejector rods 26L Further forward motion of the actuator 210 which has no further opening action on the jaws, then moves the ejector outwardly and forces the work off of the center 259, the opening rods 214 then taking the full line position of Figure 26. It will be noted that the jaw motion takes place during lost motion between the actuator 210 and the motion of the ejector. On retraction of the actuator 27!], when a new work piece is positioned between the centers by the transfer mechanism, the forward motion of the tailstock center engaging the work, moves the ejector 260 to its backward position as the work is forced onto the headstock center 259, and as the actuator 270 further retracts, it permits the spring pressed plugs 256 to close the jaws in upon the new work piece as soon as the work piece has been moved to fully loaded position between the jaws. At the end of the machining operation, the tailstock center retracts and the ejector then forces the work out of the chuck after releasing the jaws therefrom, the work sliding axially within the work holder of the transfer mechanism.

From the foregoing description of an embodiment of this invention, it should be evident to those skilled in the art that various changes and modifications might be made without departing from the spirit or scope of this invention.

I claim:

1. A work transfer mechanism comprising two pairs of parallel bars, a fixed pivot between the bars of each pair and with reference to which said bars may pivot and move axially, a work gripper carried by each pair of bars, a pivoted arm for each pair of bars having connection thereto, a lever connected to both of said arms, and means for rocking said lever, said arms and bars being proportioned and related to cause one of said work grippers to move away from one position while the other of said work grippers is moving toward said position as said lever is rocked.

2. A work transfer mechanism comprising a pair of elongated "members each having a work gripper at one end, a pivot about which both of said members may rock and move lengthwise, a rock member, and connections between said rock member and elongated members causing simultaneous motions of said elongated members as said rock member is rocked, said elongated members being proportioned and related to cause one of said work grippers to move toward a predetermined position while the other of said gripper members is moving away from the same position.

3. The combination of a pair of spaced worksupporting means, a stationary pivot member spaced from said supporting means, two pairs of bars, the bars of each pair being parallel and spaced apart on opposite sides of said pivot to rock on said pivot and move lengthwise of said bars, the bars of the two pairs being movable in two parallel planes, a work-engaging element carried by each pair of bars for engagement with a work piece, and means for moving said pairs of bars lengthwise and about said pivot, one pair of bars with its Work-engaging element from one to the other of said work-supporting means to transfer work pieces one at a time from the one to the other of said work-supporting means, and the other of said pairs of bars with its workengaging element from said other work-supporting means to transfer work pieces one by one away from said other work-supporting means.

RALPH M. GAMBLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 447,144 Clyne Feb. 24, 1891 644,279 Couch Feb. 27, 1900 666,486 Brown Jan. 22, 1901 959,456 Campbell May 31, 1910 1,596,733 Higgins Aug. 17, 1926 1,645,123 Thacher Oct. 11, 1927 1,817,099 Reed Aug. 4, 1931 1,838,692 Lovely Dec. 29, 1931 1,841,988 Smith Jan. 19, 1932 1,933,226 Smith et a1. Oct. 31, 1933 1,993,754 Smith et al Mar. 12, 1935 1,994,242 Clouse Mar. 12, 1935 2,059,546 Brandenburg Nov. 3, 1936

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