US2728238A - Motion converting mechanism - Google Patents

Description

Dec. 27, 1955 A, P S E 2,728,238

MOTION CONVERTING MECHANISM Filed June 17, 1952 2 Sheets-Sheet l Dec. 27, 1955 J p sc g 2,728,238

MOTION CONVERTING MECHANISM Filed June 17, 1952 2 Sheets-Sheet 2 United States Patent MOTION fiONVERTWG MECHANISM Jens A. Paasche, Chicago, Ill., assignor to Cline Electric Manufacturing Company, Chicago, Ill., a corporation of Illinois Application June 17, 1952, Serial No. 294,039

14 Claims. (Cl. 74-99) This invention relates to oscillatory coating apparatus and more particularly to a cam and cam follower mechanism for use in controlling the operation of spray guns in oscillatory coating apparatus.

In certain types of continuous coating processes oscillating devices are used in combination with endless work conveyors. The spray guns of the coating apparatus and the article are moved relative to each other, the spray guns being swept from one side of the article to be coated to the other. In order to save paint or other material being sprayed, it is desirable to interrupt the operation of the spray guns when they approach the edge of the article being coated. Inertia of the parts and the time required for the material being sprayed to-move from the exit orifices of the spray guns to the article to be coated necessitate interruption of the flow of coating material before the guns are positioned over the edge of the article. After turning ofi the flow of coating material the spray guns are carried past the edge of the article. Movement of the guns is then reversed and the guns are moved toward the article and then across the article. It is necessary to initiate flow of coating material at such a time that the material strikes the edge and fully coats the edge of the article. It has been found that the point of interruption of the flow of coating material and the point at which fiow of material must be initiated do not coincide.

Accordingly it is an object of the present invention to provide a control mechanism for spray guns of the type set forth that will effect an economy of material being sprayed.

Another object of the invention is to provide control mechanism for spray guns which can selectively turn off and turn on the flow of coating material so that the stream of coating material hitting the article to be coated is interrupted and again initiated at the precise desired point.

Yet another object of the invention is to provide in a control apparatus of the type set forth cam and cam followers which are individually and universally adjustable whereby to obtain the necessary degree of control.

A further object of the invention is to provide an improved double acting cam and cam follower arrangement which will achieve the objects set forth above.

Although the control mechanism of the present invention has general application, its advantages are most fully realized when the control mechanism is used in conjunction with a spray coating apparatus. Accordingly, the mechanism is hereinafter described in conjunction with such a spray coating apparatus.

A still further object of the invention is to provide an improved carriage for use in spraying apparatus of the type set forth.

The above and other objects of the invention will be more fully understood from the following description when taken in conjunction with the accompanying drawings. In the drawings wherein like reference numerals have been used to indicate like parts throughout:

Fig. 1 is an elevational view partly in cross section illustrating a spraying apparatus incorporating therein the control mechanism of the present invention, the spraying apparatus being shown in operative position over a conveyor carrying articles to be sprayed;

Fig. 2 is a view in vertical section substantially as seen in the direction of the arrows along the lines 22 of Fig. l;

Fig. 3 is a diagrammatic view on an enlarged scale of the cam and cam follower mechanism of the present in- Fig. 7 is an enlarged view in vertical section of they cam follower of the present invention substantially as seen in the direction of the arrows along the line 7-7 of Fig. 3.

Referring now to the drawings and more particularly to Fig. 1, there is shown an oscillatory spraying apparatus including as a part thereof a control mechanism made in accordance with and embodying the principles of the present invention. The spraying apparatus includes generally a conveyor 10, an oscillatory spraying unit 12, a frame 14 for supporting spraying unit 12, and a pair of control cam units 16 and 18. Conveyor 10 includes a pair of legs 20 on which are mounted a pair of spaced apart flanges 22 and 24. Mounted between the flanges 22 and 24 are chains 26 and 28, one of the chains being positioned along either side of and supporting a work support member 30. Mechanism (not shown) is provided to drive the chains 26 and 23 whereby to move them within the support flanges 2224. The support member 30 is adapted to receive and carry a work piece 32. As viewed in Fig. l, the support member 30 and associated parts are moved in a direction perpendicular to the sheet and out of the sheet whereby to carry the work piece 32 in a uniform manner beneath the oscillatory spray unit 12.

The oscillatory unit 12 is mounted upon the frame and 36 which are positioned on opposite sides of the conveyor 10 but positioned adjacent thereto. The upper ends of base members 34 and 36 are hollow whereby to receive a pair of upstanding end members 38 and 40. The end members 33 and 4b are telescopically received in and adjustable in the upper ends of the bases 34 and 36. Clamp members 42 and 44 are provided to lock the end members 38 and in any desired position within the base members 34 and 36 respectively. The upper ends of end members 38 and 40 are provided with hemispherical caps 46 and 48 which close the ends of these members. Each of the end members is provided with a pair of bosses, these bosses being hollow and having an axis extending substantially perpendicular to the lonigtudinal axis of the associated end member. End member 38 is provided with bosses 50 and 52 and end member 40 is provided with bosses 54 and 56. The bosses 50 and 54 which are positioned adjacent the upper ends of the end members 38 and 40 support an upper support member or track 58. The ends of tracks 58 are threadedly received by the bosses 50 and 54 and are held in firm relationship thereto by means of hexagonal nuts 60 and 62. The lower bosses 52 and 56 similarly support a lower track 64 whose ends are threadedly received by the bosses and held in Patented Dec. 27, 1955' Frame 14 includes a pair of base members 34 as: a hollow tube or pipe and thereby presents: curved outer. surfaces.

Mounted uponthe tracks 58 and 641 is the carriage of the spraying apparatus 12. The carriage as may bebest seen in Fig. 2' includes apairof castings and 72 which have shapes substantially as illustrated in Fig. l. 76 hold. the castings in. assembled relationship to form the bodyfor; the carriage. The carriage includes a pair of. outwardly directed arms 78 and: 80- formed on thempper end thereof. Mounted withinthese arms 78- and 80 are wheels 82 and 84, these wheels-beinggmounted onsuitableaxles-86-and 8S; Immediately below the wheels 82 and 84 there are provided openings in the castings 7.0- and 82, these openings receiving the upper track 58; see Fig. 2. The wheels 82 and 84 ride upon the upper surface of track 58 whereby to support the carriage thereon.

The. lower end of the carriage is also provided with outwardly extending arms, these arms being indicated by the numerals 80 and 92. Arms 90 and 92 also extend. laterally outwardly as best seen in Fig. 2 wherebyto accommodate a pair of Wheels 94- and 96. The

wheels 94 and 96 are supported upon axles that are mounted by means of bolts 98 and 100. The wheels 94 and 96 are spaced apart whereby to receive the a lowertrack 64- therebetween, the track 64 extending through suitable apertures in the castings 70 and 72.

A second pair of wheels 89 is mounted on the carn'age in position to contact the upper rail 58. A suitable housing 91- is provided to enclose each of the wheels 89.

It is to be notedthat all of the wheels 82, 84, 89, 94 and. 96 have concave grooves formed on the surface thereon to cooperate with the tracks 58 and 64. The

wheels 82 and 84 contact the upper surface of track 5 8, wheels 89 contactthe sides of' track 58, and the wheels 94.and= 96 contact the sides of track 64. The wheels 82 and 84 support the carriage in a vertical direction and the wheels 94 and 96 stabilize the carriage in; a horizontal direction. This arrangement of the wheels provides'for easy movement along the tracks 58 and 64 with a minimum of vibration and otherirregnlaritiesin the path of travel of thecarriage.

Means isprovided to reciprocate the carriage upon the; tracks 58 and. 64; This reciprocating mechanism includes a motor 102, a speed reducer'104, and a pair of sprocket wheels 106 and 108ithat drive a continuous or endless chain 110. Motor 102 is provided with an output shaft 112 on the end of which is mounted a v shaped pulley 114. Connection is made between motor 102 and the speed reducer 104 by means of a- V -shaped belt 116' thatengages a policy 118 attached to the input shaft 120: of the speed reducer 104.

drive the speed reducer 104. The output shaft 122 of speed reducer 104 has mounted. thereon thesprocket 108. Referring'to Fig. 2 in the drawings there isshown that supports sprocket wheel 106. Rotation of sprocket-wheel 108 drives chain llti-which in turn drives the supporting sprocket wheel 106.

Referring now'to Fig. 2 it will be seenthat thechain.

Stud.

110 has fixedly attached thereto a stud. 132. 132 is providedzwith an enlarged head 134-that engages apairofvertically positiontrackmembers 136 fastened to the rear of casting 72. The track members' -.136.re.-

ceive the head 1340f stud-132 andaccordingly movement of stud 132- will move the carriage. and its asso- A plurality of bolts such as bolts 74 and It will be seen that operation of motor. 102 will serve to- 4. ciated parts. More particularly when the chain 110 is travelling in the directionv of the arrow the carriage will be moving to the right as viewed in Figure 1, the stud 132 being positioned at the upper end of track 136. When the carriage reaches the vicinity of sprocket wheel 108, the stud 132 will be moved downwardly within track 136 and will. reverse its direction of travel. This in turn will reverse the direction of travel of the carriage whereby to give a complete cycle of operation of the conveying mechanism.

The apparatus of the present invention is capable of coating articles travelling at extremely high rates; In order to coat articles travelling at high rates of speed it is necessary to oscillate the carriage and associated spray guns at correspondingly high rates of speed. Inasmuch as the ca riage and its associated parts must reverse its direction of travel completely at each end of the spraying stroke, considerable stress is placed upon the operative parts. due to the inertia of the, carriage anditsa attachments. Means is provided to reduce the shock incident to=thereversal of the direction of travel of the carriage at the end of its strokes andsto aid in starting the-carriage on-its return stroke. Means is also provided to minimize vibration and related movements. "[0 this end a heavy' coiiedspring 155 is provided'adjacent eachend of the path:-

of traveltof the carriage. One endof the spring is=lefti open and free, and the other end 137' of the spring is clamped between' a nut 139 and an internally threaded: cap 1.41: Both the nut 13? and the cap 141% are threadedi uporvv a stud 143 that is firmly aihxed as by weldingto:

the end members 38-40. The external diameter of. cap:

141 is slightly less than the inner diameter of spring whereby the cap supports'thespring for a portion of its length; The position of the end of the springs 135- can. be; adjusted by means of the screw t reads on the stud l43-andithe cooperating threads on the nut 139 and cap 141; A-pad 145 made of any suitable material, such as leather, is affixed to'each side of the carriage in position. to contact the free end'of springs: 135'- when the carriage reaches the end of its path of travel. Preferably the springs. 135 extend inwardly toward each other a-distance such thatithespring is compressed thereby absorbing any shock and vibrationandalso-serving to aid in'movingthe carriage in-the opposite direction.

Mounted on the translatable carriage is a pair of? spray guns 138'that are supported-charms 140. Suitable clamps 147 and clamping nuts 14-9 are provided adjustably. to'

positionithesprayguns 138 on arms 1403 Arms are carried by a rod 142 that is adjustably supportedin' a tubular member 144-. More particularly rod-1'42- fits within tubular. member 144: and is adjustable upwardly and downwardlyby means ofa clamp 146; Tube lM-is carriage. The; other endof' conduit 162iconnectswith a line 164 which interconnects the source of material to be sprayed with the spray guns 1-38; inasmuch as the carriage reciprocatesupon' the tracks 58" and 64; means is providedto holdthe flexible lines 148' and'15itabovc' the apparatus whereby. to give free movementv of the carriage. To this enda pair of telescoping support members 1'66a'nd 168' are provided, the lines 158 and 148 being'mounted ontheupper end of member 1681 The lower support member.166 ismounted upon thesupport 12,4.which is stationary. A. elarnp. 1370. is provided so Accordingly when the carriage. moves that the level of the lines as supported by member 168 can be adjusted.

When the conduit is connected to the spray guns 138, operation of the spray guns is obtained by introducing air from line 148 into the spray guns. This is accomplished by actuating the air control valve 152. Referring now to Fig. 6 the structure of valve 152 will be described in detail. Coupling pipe 158 is threaded as at 172 for attachment to a union member 174. Extending around the lower end of union member 174 is an outwardly directed flange 176. Surrounding the union member 174 is a ring 178 which has an inwardly directed flange 180 formed around the upper edge thereof. The inner diameter of flange 184) is smaller than the outer diameter of flange 176 whereby to cause engagement between these flanges. The lower internal circumference of ring 178 is provided with screw threads 182 which engage complementarily shaped screw threads on the body 184 of valve 152. Pipe 150 communicates with a chamber 186 formed in body 184 and further passages 188 and 190 are provided which communicate with pipe 192 which is threadedly mounted in body 184. Pipe 122 is connected through suitable coupling members to the air line 154.

A valve head 194 is reciprocably mounted within valve body 134. Also provided is a valve stem or control member 196 which is vertically and reciprocably mounted within valve body 184. The valve head 194 is attached to the control member 196 by means of a screw 19?. The lower end of valve control member 196 is provided with a nut 200 having a rounded lower side 201 and a spring 202 is positioned between nut 2% and the valve member 184 whereby to urge valve head 194 to the seated position. in the seated position valve head 194 efiectively closes passage 188 thereby preventing compressed air from reaching the spray guns 138.

In the operation of the spraying apparatus, it is desirable to have the spray guns in operation when they are positioned above and directed toward the work piece 32. At the ends of the path of travel of the carriage, it is highly desirable to turn off the spray guns to save material being sprayed and to eliminate difliculties occasioned by spraying paint and similar materials on parts of the spraying apparatus. Further it is desirable to have the spray guns travel past the edges of the work piece 32 as viewed in Fig. 1 to insure that the edges of the work piece are properly coated. Similarly it is necessary to turn on the spray guns at the proper moment when they again travel toward the work piece 32 on the return path of travel of the carriage.

It has been found that due to inertia and other factors the spray guns must be turned off at a point in time slightly prior to that at which the spray guns reach the edge of work piece 32. Similarly in turning on the spray guns it has been found necessary to initiate operation thereof at a point in time prior to the arrival of the spray guns along the edges of the work piece 32. Furthermore the point at which the spray guns are to be turned 01f and the point at which the spray guns are to be turned on do not coincide and accordingly separate means must be provided for turning off and turning on the spray guns 138.

To this end a cam and cam follower arrangement are provided in the present invention so that proper operation of the spray guns is obtained. In addition the cams and cam followers of the present invention are so constructed that they can be individually adjusted and universally adjusted to obtain the optimum efficiency of operation.

The means for operating the valve 152 include a double acting cam follower member generally designated by the numeral 204 and a plurality of cams 206, 208, 210 and 212. The cams 206 and 208 are mounted on a rod 218 that extends substantially parallel to and spaced between the tracks 58 and 64.

One end of rod 218 is received in an adjustable cam mounting rod support 220 which is in turn supported by a C clamp 222 held together by a plurality of bolts 224. The support 220 is provided with an adjustment clamp 226 which permits adjustment of the position of rod 218 inwardly and outwardly with respect to the end member 38. A similar support structure is used to support the cams 210 and 212. Accordingly like reference numerals have been used in designating these parts. It would mean that this construction permits the cams to be adjusted vertically and horizontally and inwardly and outwardly with respect to the tracks 58 and 64.

Referring now to Fig. 3 the structure of the double acting cam follower 204 and the cams 210 and 212 will be described in detail. The double acting cam follower 204 includes a body 228 that is pivotally mount. ed on a stud 236 on casting 70. A bearing support plate 232 is mounted on the casting in a recess therein and movement between the casting '70 and the bearing plate 232 is prevented positively by means of a pin 234. Three roller bearings 236 are disposed around and mounted upon the plate 232, the axis of rotation of each bearing lying parallel to the plane of rotation of the cam follower 204. The bearings 236 are positively retained in mounted position by means of a retainer ring 238 that surrounds the plate 232 and associated bearings.

A hardened contact plate 240 is mounted on the surface of body 228 that is disposed toward the bearings 238. Relative movement between the plate 240 and body 228 is prevented by the means of a plurality of pins 242.

As is best seen in Figure 3, body 228 is substantially tear drop shape and is positioned with the pointed end disposed upwardly. A relatively large recess 243 is formed in the larger portion of the body 228. Disposed within recess 243 is a ball bearing assembly 244 which provides for smooth rotation of the body 228 about the stud 230. In order to provide for easy repair a bearing sleeve 246 surrounds the stud 230 at the point at which the ball bearing assembly 244 is positioned. Inasmuch as the cam follower 204 is to assume any one of three distinct positions, the contact plate 240 is provided with suitably spaced recesses corresponding to each of the three positions. Rotation of the body 228 necessitates movement of the body 228 along the axis of stud 230 since the bearings 236 must be moved out of the grooves in plate 240 before they can be moved to the next groove. To this end there is provided a spring 248 and a cap 250 that are disposed between the head 252 of stud 236 and the bearing sleeve 246. The cap 250 serves to retain the spring 248 and the spring continually urges the body 228 toward the bearings 236. All of the parts are held in assembled relationship by means of a nut 251 which engages the threaded end of stud 230 and a washer 253. This structure insures that the cam follower retains the desired position when once in position, yet permits change in the position of the cam follower.

The upper or pointed end of body 228 has a slot formed therein to provide a pair of arms 254 and 256. These arms are provided with apertures which receive an axle 258 that supports a contact roller 260. In order to center roller 26d and insure its smooth operation a pair of washers 262 are provided on either side thereof. The roller 260 contacts an arm 264 which is pivoted on casting 70 by means of a screw 266. Arm 264 is actually disposed between the roller 260 and nut 200 as may be best seen in Figures 3 and 6.

In order to provide means for moving or changing the position of cam follower 204 a plurality of arms 265, 267 and 269 is provided. Arm 267 is diametrically opposed to roller 260 and the arms 265 and 269 extend radially outward along lines that intersect at the center of stud 230. Preferably the angular dispositions between arms 265 and 267 is the same as that between 267 and 269.

2' The structure of cams 210. and 212 is best shown in. Figs. 4 and 5. Cam 219 will. be described in detail. A circular collar 26% is provided; the internal diameter.

of the collar heing slightly greater than the external" diameter of rod 218; Extending radially outwardly from collar 268' is a projection 270 which is provided with an aperture. Mounted on either side of the projection 270 are plates 272 and 274, these plates having apertures that are aligned with the aperture in projection 270. Extending. through the aligned apertures is a stud 276 having an enlarged portion 278, a. head 280, and

a threaded end 282'. The stud, the plates and the projection are held in assembled relationship by means of a nut.28'4 that. engages the threaded end of stud 276. The

upper ends of plates 272 and 274 receive a rivet 286' on whichis rotatably mounted a contact roller. 233.

Referring now particularly to Figure 4 it will be seen that the plates 272 and 274 have a lower edge 2% that is straight for a portion thereof and is then curved upwardly as at 292. The plates are held in the position shown in Figure 4 by means of a coiled spring2 3 having one end attached to the head 280 as at 294 and the other end attached to-plate 272 as at 296.

Although the spring 293 holds the plates in the position shown in. Figure 4, pressure applied from the right as viewed in Figure 4 can move the plates to the left, the plates pivoting about the stud 276. This is diagrammatically illustrated in Figure 3. In order to hold the cam in. the desired position upon rod 218 and yet permit adjustment of the position of the cam, a set screw 298 position of the cam follower is changed. More specifically, the finger 267 contacts the roller 286 of cam 210, thus moving cam follower 294 to position B. This movement of the cam follower removes roiler 260 from contact with arm 264 and thus closes valve 152. The cam follower retains this position until moved.

When the cam follower approaches cam 212, the finger 269-will be in position to contact the roller 23%. However, cam 212'will be ineffective to change the position of the cam follower since the cam will be moved to the position shown in dotted lines. passes cam 212 the direction of travel of the carriage is reversed and arm 269 again contacts roller 288. This time the cam' will remain in an upright position due to the surface 290, and will be effective to move the cam follower to position C. This, in turn, initiates the operation of the spray guns 1328 by opening valve 152. Continued movement of the carriage brings finger 267 into contact with the roller 238 of cam 211i; Cam 210 will be ineffective to change the position of cam follower 204 and will be moved to the position shown in dotted lines. This sequence of operation is repeated when the cam follower engages the cams 2M and 208-.

ItWlll be seeen that there has been provided a carriage and a cam and cam follower structure which fulfills all the objects and advantages set forth above. Although certain preferred forms of the invention have been given for the purpose of illustration, it is to be understood that various changes can be made therein without departing from the spirit and the scope of the invention. Accordingly, the invention is to be limited only as set forth in the following claims.

Theinvention is hereby claimed as follows:

1. The combination comprising a cam follower, said cam followerhaving an operative and inoperative position, apair of'cams positioned adjacent said cam f'ol- After the cam follower lower, means to move said cam follower and said cams relative to each other, one of said cams actuating said cam follower when the cam follower is moved past said cams in one direction, and the other of said cams actuating the said cam follower when the cam follower movespast said cams in the other direction.

2.'The combination comprising a camfollower, said cam follower having operative and inoperative positions, a pair of cams positioned adjacent said cam follower, means to move said cam follower and said cams relative to each other, one of said cams being effective to move said cam follower to the inoperative position when saidcam follower is moved past said cams in one direction, and. the other. of said cams being effective to move said cam follower to the operative position when said cam follower and said cams are moved past. each other in. the opposite direction.

3. The combination comprising a cam follower, said cam follower having an operative and an inoperative position, a pair of cams positioned adjacent said cam follower, means to move said cam. follower and said cams relative to each other, one of said cams being effective only to move said cam follower to the operative position when said cam follower is moved past said cams, and the other of said cams being effective only to move said camfollower to the inoperative position when the cam follower is moved past said cams.

4. The combination comprising a cam follower, said.

cam follower having an inoperative and an operative position, a pair of cams mounted adjacent said cam follower, and means for moving said cam. follower. and said camsrelative to each other,.one. of said cams being effec tive to-actuate said cam follower when the cam follower moves in one direction past said cams, the other of; said cams actuating said cam follower when the cam follower returns in the other direction.

5. The combination set forth in claim 4;.wherein said.

cams include cam fingers pivotally mounted, spring means urging said cam fingers to an upright cam follower engaging position, and abutment means preventing pivotalmovement of said cam fingers in one direction.

6. The combination set forth in claimv 5, wherein said cam fingers are mounted to pivot only outwardly away from each other.

7. The combination comprising acam follower, means rotatably mounting said cam follower for rotation about said cams in one direction, and the other of. said: camsbeing effective to rotatesaid cant follower to the operative position when said cam follower is moved past said cams: in the opposite direction.

8. The combinationcomprising acam: follower, said cam follower having an operative and-an inoperativeposition, means to reciprocate said camfollower alonga-predetermined path of travel,.a pair of cams-fixed adjacent.

each extre. 1. y of thepath of travel of said cam follower,

one of said cams at each end of said path of. travel sew-- ing to move said follower to the inoperative: position:

and the other of said cams servingto move-saidcamfollower to the operative position.

9. The combination comprising a cam follower, said cam follower having an operative and an inoperative POSi? tion, means to rcciprocatesaid carnfollower along a-predetermined pats of travel, a pair of cams fixed adjacent each extremity of the path of. travel of said cam follower said cams being arranged in a'line substantially parallel.

to the path of travelof said carn follower, the outer cam of each pair of cams being effective to move said cam follower to the operative position and the innermost cam of each pair of cams being effective to move said cam follower to the inoperative position.

10. The combination comprising a cam follower, said cam follower having an operative and an inoperative position, means to reciprocate said cam follower along a predetermined path of travel, a support positioned adjacent each extremity of the path of travel of said cam follower, a pair of cams fixed to each support, said cams being arranged in a line substantially parallel to the path of travel of said cam follower, the outer cam of each pair of cams being effective to move said cam follower to the operative position, and the innermost cam of each pair of cams being effective to move said cam follower to the inoperative position, each of said cams being individually and independently adjustable with respect to each other and the associated support.

11. The combination comprising a cam follower, said cam follower having an operative and an inoperative position, means to reciprocate said cam follower along a predetermined path of travel, a pair of cams fixed adjacent each extremity of the path of travel of said cam follower, said cams being arranged in a line substantially parallel to the path of travel of said cam follower, each of said cams including a pivotally mounted cam finger, spring means urging said cam fingers to an upright cam follower engaging position, abutment means preventing pivotal movement of said fingers in one direction, the outer cam of each pair of cams being effective to move said cam follower to the operative position, and the innermost cam of each pair of cams being effective to move said cam follower to the inoperative position.

12. The combination as set forth in claim 11, wherein said cam fingers are mounted to pivot only outwardly away from each other.

13. The combination, as defined in claim 8, wherein said cam follower is pivotally mounted and includes three cam engageable elements extending for selective engagement with certain of said cams, one of said elements between the others being actuated by said cams serving to move the cam follower to the inoperative position, a second element being actuated by the cam at one extremity of the path of travel serving to move the cam follower to the operative position, and a third element being actuated by the cam at the opposite extremity of the path of travel serving to move the cam follower to the operative position.

14. The combination, as defined in claim 12, wherein said cam follower is pivotally mounted and includes three cam engageable elements extending for selective engagement with certain of said cam fingers, one of said elements between the others being actuated by said innermost cam fingers to move the cam follower to the inoperative position, a second of said elements being actuated by one of said outermost cam fingers to move the cam follower to the inoperative position, and the third of said elements being actuated by the other of said outermost cam fingers to move the cam follower to the operative position.

References Cited in the file of this patent UNITED STATES PATENTS 1,447,895 Schafer Mar. 6, 1923 1,973,927 Motley Sept. 18, 1934 2,246,502 Bramsen June 24, 1941 2,360,869 Gilbert Oct. 24, 1944 2,512,612 Deakin June 27, 1950 2,610,605 Paasche Sept. 16, 1952 2,613,634 Johns et a1 Oct. 14, 1952 2,648,234 Lester Aug. 11, 1953

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