US2330119A

US2330119A - Stock-feeding mechanism

Info

Publication number: US2330119A
Application number: US435395A
Authority: US
Inventors: James L Giffen
Original assignee: V & O Press Co
Current assignee: V & O Press Co
Priority date: 1942-03-19
Filing date: 1942-03-19
Publication date: 1943-09-21
Anticipated expiration: 1960-09-21

Description

Sept. 21, 1943. J. L. GIFFEN 2,330,119

STOCK FEEDING MECHANISM Filed March 19, 1942 3 Sheets-Sheet l ATTORNEY Sept. 21, 1943. v GlFFEN v 2,330,119

STOCK FEEDING MECHANISM Filed March 19, 1942 3 Sheets-Sheet 2 INVENTOR James L. fiz'flen ATTORNEY Patented Sept. 21, 1943 STOCK-FEEDING MECHANISM James L. Gifien, Hudson, N. Y., assignor, by

mesne assignments, to The V & Press Company, Hudson, N. Y., a partnership consisting of Marshall Field and Charles G. Cushlng Application March 19, 1942, Serial No. 435,395

20 Claims.

This invention relates to stock feeding mechanism and more particularly to mechanism adapted to intermittently feed relatively thin sheet stock generally supplied in strip form and wound in coils.

Considerable difficulty has been experienced in properly, and efiiciently, automatically feeding relatively thin strip stock into position between the tools of a punch press, and many forms of feeding mechanisms have been provided for this purpose, the most common being of the type known as roll feeds. In roll feeds cooperating rotating rollers are provided to grip the stock and, as they rotate, to feed it along step by step as conditions require. In such feeds the stock often slipped, or over-ran, and in an attempt to avoid these faults and to drive the rollers in timed relation with the press, various forms of rather complicated and expensive roll actuating mechanisms were provided. Although roll feeds have been found preferable, plain friction feeds have also been provided wherein the stock was intermittently gripped and pushed along the desired amount and then released to stop the feed thereof. In this form the stock was particularly liable to be damaged by scratching should the gripping members slip thereon, although the possibility of over-running was practically avoided.

One of the objects of this invention is to provide a stock feeding mechanism wherein the desirable features of roll feed and of the friction feed are combined whereby the stock will be firmly gripped without possibility of it slipping, moved along by swinging or rotary motion of the feeding members, and intermittently gripped and released to insure positive stopping and starting of the feed thereof.

Another object is to provide, in a mechanism of the above nature, superior means to adjust the pressure applied by the feeding members upon the stock, while the mechanism is in operation.

Still another object is to provide means, in a mechanism of the above type, whereby slight variations in the amount of feed of the stock may be made while the machine is in operation.

A further object is to provide, in a stock feeding mechanism, means actuated by swinging or the rotary movement of the feeding means to cause the latter to apply pressure upon the stock to insure proper and positive feeding thereof.

It is also an object of this invention to provide a stock feeding mechanism of improved construction, whereby the same will be relatively simple, durable and inexpensive in construction, as well 7 struction hereinafter described and claimed, it

being understood that various changes in the precise embodiments of the invention herein disclosed may be made within the scope of what is claimed, without departing from the spirit of the invention.

The essential features and principles of this invention are fully shown embodied in the mechanisms illustrated in the accompanying drawings, wherein:

Figure 1 is an end view of a punch press having a stock feeding mechanism embodying the features and principles of this invention in operable association therewith;

Figure 2 is an enlarged front view of the stock feeding mechanism shown in Figure 1 looking in the direction of arrow 2 in that figure and showing strip stock leading to said mechanism from a coil thereof;

Figure 3 is an enlarged top plan view of the stock feeding mechanism of this invention and looking in the direction of arrow 3 of Figure 2;

Figure 4 is a side view of the mechanism looking in the direction of arrow 4 in Figure 3;

Figure 5 is a sectional view taken along the line 5-5 of Figure 3;

Figure 6 is a sectional view taken along the line 6-6 of Figure 3;

Figure! is a sectional view taken along the line 'I--'l of Figure 3;

Figure 8 is a side view of a somewhat modified form of stock feeding mechanism which embodies certain of the essential features and principles of this invention;

Figure 9 is a side view of another modified form of feeding mechanism shown in cooperating relation with a conventional form of punch press;

Figure 10 is an enlarged side view of the form of feeding mechanism shown in Figure 9;

Figure 11 is an end view of the same; and

Figure 12 is a top plan view of the same.

Referring now to the drawings wherein like reference numerals designate like parts throughout the several views, the numeral H (see Figure 1), denotes the frame of a punch press having the usual crank shaft l2 adapted to be rotated through a flywheel l3 and belt H by any suitable source of power (not shown); The crank shaft l2 by means of a pitman I5 is adapted to reciprocate a punch carrying slide l8 toward and away from a die (not shown) but usually secured to a die block l1 seated upon the machine bed l8. Strip stock l9 (see Figure 2) wound into a coil 2| which is loosely supported upon the arms of a reel 22 is shown as being provided to be fed by mechanism embodying the features and principles of this invention across the bed l8 and between the punch and die (not shown) to form it into the desired product.

The crank-shaft I2 is extended through the press frame H and has an adjustable driving crank 23 for the strip feeding mechanism secured thereto. The driving crank 23 includes a crank knuckle 24 adapted to be adjusted along a slide 25 by means of an adjusting screw 28, to vary the eccentricity between the axis of the knuckle 24 with the axis of the crank-shaft I2 and thus vary the throw of a connecting rod 21 pivotally secured at its upper end to the knuckle 24. The lower end of the rod 21 is connected to an arm 28 adapted to actuate the strip feeding mechanism, due to the above described connection with the crank shaft l2, in timed relation with the press action and particularly the action of the punch carrying slide l8. The rod 21 is adapted to be adjusted in length, for instance, by means of a turnbuckle 29.

The strip stock I9 is led into the mechanism of this invention in between cooperating rockable members 3| and 32, (see Figures 4 and 7), whose opposing surfaces are arcuate in cross-section and which are herein shown in the form of opposing and cooperating rollers, from the coil 2| through a friction device comprising upper and

lower plates

33 and 34. The

plates

33 and 34 are adapted to be drawn together to vary their pressure on the stock l9 by means of

clamp screws

35 and 36. The rollers, or members, 3| and 32 are securedto, or formed integral with,

shafts

31 and 38 respectively. The shaft 38 extends between and is journaled in

opposing side frames

39 and 4|, the arrangement being such that the shaft 38 and the roller 32 rotate about a fixed axis.

The shaft 31 extends between and is journaled in

opposing arms

42 and 43 which are, respectively, pivotally mounted to

uprights

44 and 45 by means of

stud shafts

46 and 41, secured in the

uprights

44 and 45, respectively, by set screws 48. The axes of the rollers 3| and 32 are substantially in vertical alignment whereby the roller 3| is adapted to swing toward and away from the roller 32 in substantially a straight line,-when the

arms

42 and 43 are rocked on the

respective stud shafts

46 and 41, the axis of the roller 3| and of the

stud shafts

46 and 41 being on a line substantially at right angles to the vertical line of the axes of the rollers 3| and 32. The aforesaid mechanism actuating arm 28 is secured to the shaft 31 whereby reciprocating movement imparted thereto from the crank shaft |2, through the crank knuckle 24, the slide 25 and the rod 21, will rock the roller 3| about the axis of the

shafts

46 and 41. The rocking of the roller 3| in one direction, for instance in the proper direction to fed stock I9 is caused, when the arm 28 moves downwardly, and in the other direction when the arm 28 moves upwardly. Thus if one of the rollers 3| and 32 is moved relatively toward the other to grip the stock l9 therebetween said stock will be fed along when the arm 28 moves downwardly.

It is required, when the arm 28 moves upwardly under the above conditions, that the rollers be separated to avoid a back feed of the stock.

In accordance with the features and principles of this invention, the means whereby one of the rollers 3| and 32, in this instance roller 3|, is moved toward the roller 32 to grip the stock l8 therebetween, includes

rockable members

48, 5|, and 52 and these, with another rockable member 63, are also arranged to impart corresponding stock feeding rocking movement to the roller 32 in timed relation to the stock feeding movement of the roller 3|, imparted thereto by the arm 28 and the aforesaid associated parts. In this instance the

rockable members

49, 5|, 52, and 53 are in the form of toothed gears, gears, 48 being secured to the shaft 31 of the roller 3|, gear 5| being freely rotatable on the

stud shafts

41 and 48, a gear 52 being secured to each end of a shaft 54, and gears 53 being secured to the shaft 38 of the roller 32. The shaft 54 extends between and is journaled in the

side frames

39 and 4|.

Brake

drums

55 and 56 are secured to the shaft 54, one at each of its ends, and

suitable brake bands

51 and 58 are provided for these

drums

55 and 56, respectively. The

brake bands

51 and 58 are adjustable while the mechanism is operating, to vary the pressure thereof upon the

drums

55 and 56, by means of an adjusting screw 69 and a compression spring 6| in the usual manner. In this instance the

brake bands

51 and 58 are anchored to prevent them rotating, by being secured to the shaft 31 of the roller 3| by means of

links

62 and 63 respectively. By this arrangement the combined action of the brake drums and bands resists the rocking movement of the shaft 54 and, through the

gears

52, 5|, and 49, resist the rocking movement of the roller 3| by the arm 28. This brake action on the part of the brake drums and bands causes the

arms

42 and 43 to swing downwardly about their pivot point at the

stud shafts

46 and 41, the rocking force imposed on the shaft 31 causing the gears 49 to fulcrumat their engaging point with the gears 5| and impose a forceupon the

arms

42 and 43 to swing them downwardly, when the arm 28 is moved downwardly by the crank-shaft I2. This action causes the roller 3| to first move toward the roller 32 and to grip the stock I 9 therebetween, whereby it is then fed along due to the immediately following rocking movement imparted to the roller 3| by the arm 28 and, through the gears, to the roller 32. The stock |9 between the rollers 3| and 32, under these conditions, is gripped thereby by pressure imposed, to some extent by the force of the downward thrust of the arm 28, and, to a greater extent by the braking action of the brake drums and bands upon the roller 3|, to cause the aforesaid fulcrum action between the meshed teeth of the

gears

49 and 5| and the downward swinging of the

arms

42 and 43.

Reversely, the upward movement of the arm 28 rocks the roller 3| but before such rocking movement takes place the roller 3| is raised from the roller 32 to release the grip upon the stock due to the combined action of the brake drums and bands and the aforesaid fulcrumming action between the

gears

49 and 5 I. During this period of no feeding of the stock, the press is in operation to cause the punch, or other tool, carried by the slide I6 to operate upon the stock presented thereto by the subsequent feeding operation of the rollers 3| and 32.

In addition to the pressure applied to the stock I 9 by the roller 3|, as above described, the arrangement of anchoring the

brake bands

51 and 58 to the shaft 31 of the roller 3| by th

links

62 and 63 imposes an additional pressure thereon through the shaft 31 and the roller 3|. Thus the brake mechanism, comprising the

drums

55 and 56 and the

bands

51 and 58, causes two distinct pressures to be imposed on the stock I9 insuring a tight non-slip gripping of the same by the rollers 3| and 32, both pressures being in the same direction and added together. In instances where still more pressure is required means is provided, as shown herein, to do so, and this means includes

compression springs

54 and 85, which react respectively, between

nuts

65 and 61 screw-threaded on studs 88 and 89 respectively which are respectively screwed into the side frames 39 and M, and the outer ends of the

arms

42 and 43 respectively. Adjustment of the

nuts

68 and 51 on the respective studs 88 and 89 may be made while the mechanism is in operation to vary the effective pressure between the rollers 3i and 32 caused by the

springs

68 and 85. It will be understood that the brake action on the

arms

42 and 43, causing them to raise, to release the stock I9 from gripping action of th rollers 3t and 32, is sufficiently strong to overcome the compression of the

springs

68 and 65 to permit the

arms

42 and 43 to be raised.

While under ordinary conditions the amount the stock is fed at each downward stroke of the arm 28 may be varied by adjustment of the crank-knuckle 28 on the slide 25 to change the eccentricity thereof in respect to the crank-shaft I2, it is often desirable to make relatively fine adjustments while the machine is in operation, ad justment of the crank-knuckle 24 being impractical and dangerous when the machine is in operation. Means is herein provided for the above purpose and comprises threaded studs H screwthreaded into the side frames 39 and M and extending upwardly through the

arms

42 and 43 at their free ends. A flanged nut I2 is screwthreaded onto each of these studs II with its flanged portion 13 adapted to engage with the

respective arm

42 and 43 when they are moved up- Wardly. Adjustment of the nuts I2 varies the.

amount the

arms

42 and 43 may raise at the release operation as above described, whereby, upon the downward stroke of the arm 28, a slight delayed action will take place before the

rollers

35 and 32 are rocked, thus varying the amount the stock I9 is fed. For instance, screwing down on the nuts 12 will slightly lengthen the length of stock fed while screwing up thereon will slightly shorten the length of the stock fed.

Provision is also made and shown herein whereby the rollers 33! and 32 may be manually separated, for instance to initially thread stock I9 therebetween, and the means for so doing includes a cylindrical member 14, secured to the shaft 58. As herein shown the member 18 is an extension of the brake drum 55 and is provided with peripherally spaced apart holes 15 in which a tool may be inserted to rock the shaft 54 to swing the roller 3| upwardly away from the roller 32.

There is illustrated in Figure 8 a form of stock feeding mechanism which is somewhat simpler in construction and wherein some of the features above referred to are omitted. In this form a fixed axis roller 8i, corresponding to roller 32 of the preceding form, cooperates with a roller 82, journaled in bearing boxes 83 at each end of its shaft 84. The bearing boxes 83 are arranged to slide vertically in slots 85, provided in side frames 88 for this purpose. The upward sliding movement of the boxes 83 is limited by adjusting screws 81 threaded in plates 88 secured to the side frames 88. A gear 89 secured to the the fixed axis roller 8| and is also in mesh with a gear 94 secured to a shaft 95 journaled in the side frame 88.

A brake drum 96 secured to the shaft 95 is arranged to be acted on by a brake band 91 which, as in the preceding form, is adjustable by means of a screw 98 and a spring 99. In this instance the brake band 91 is anchored to the side frame 88 by a pin IIJI. In this form the roller 82 is first forced downwardly toward the roller M to grip stock therebetween when the rack 9B is reciprocated downwardly by the crank-shaft I2 and is then rocked to feed the stock to the tools carried by the slide It. Action of the brake mechanism through the gears 99 and 89, as in the preceding form, causes the gear 89 to fill crum on the gear 94 to slide the bearing boxes 83 and withthem the roller 82 toward the roller 8% when the gear 89 is acted on by the rack 9i, after which the rollers 82 and Eli are rocked to feed stock. Upward movement of the rack 9i reverses these operations whereby the roller 82 is first raised to release the stock and then the rollers 8i and 82 are rocked into their initial position, the amount the rollers and t2 are separated being limited by the size of the teeth'on the gears 89 and 92 so that they will not become out of mesh, whereby this form of mechanism differs from the preceding form wherein. this inconvenience is not present.

The form of mechanism shown in Figures 9 to 12 inclusive, embodies certain of the features and principles of this invention and is somewhat simpler in construction than the preceding forms. In this form a swingable, or rockable, member III is used in place of the upper roller 3I. The member II! constitutes one arm of a bell crank H2 secured by a set screw H3 to a shaft H4. The other arm II 5 of the bell-crank H2 extends substantially at right angles to the member III andis connected by suitable means, such as the rod 27, to the crankshaft I2 of the punch press, and as in the form shown in Figures 1-8 inclusive, whereby the member II! will be rocked in timed relation with the press operation.

The shaft H4 extends between and is journaled at its ends in spaced apart arms H8 and II! of a part II8 which is pivotally mounted to an upright H9 upon a shaft If. The upright I I9 is, in this instance, formed integral with a base I22 which is adapted to seat upon the press bed, or bolster plate, I23 and be secured thereto by bolts I28.

A roller I25, rotatably mounted on a shaft I28, is in operative alignment with the rockable member III. The shaft I26 extends through a bearing, lug I21 formed on the base I22 and is secured thereto against movement therein by a nut I28. By this arrangement the roller I 25 is free to rotate when stock is gripped between it and the lower end I29 of the rocking member III and the latter is rocked. The lower end I29 of the member III is arcuately shaped to correspond to the periphery of a roller much larger in diameter than the roller I25, the length of the chord of the arc, which are is struck from the center of the shaft H4, being sufiicient to provide the desired arcuate stock feeding surface.

The downward gripping pressureof the member III upon the stock I9 is produced by the use of a cooperating brake drum and brake band I3I and I32 respectively as in the previous forms, although the arrangement is somewhat diiferent. In this instance, the adjustable brake band I32 is secured to the member III by a screw member I33 which forms the pivot pin for the two parts of the brake band, and the brake drum I3I is secured to the arm II1 of the part II8 by a.

screw I34. The action of the brake drum I3I and the brake band I32 is similar to that the corresponding parts of the previously described forms, the brake band I32 rocking with the member II I and cooperating with the stationary brake drum I 3| to cause the arms I I8 and H1 and with them the member III to swing about the pivot shaft I2I to move the member III downwardly to grip stock I9 between the arcuately shaped end I29 of the member III and the roller I25 before the member III is rocked to feed stock under the tool, mounted in the press slide I8, when the crank-shaft I2 actuates the rod 21 to swing the arm II of the bell-crank II2 downwardly. Reverse action of the crank-shaft I2 upon the rod 21 will swing the arm H5 and cause the member I I I to be raised away from the roller I25 to release the gripping action thereof on the stock I9 before the member I II is rocked in stock nonieeding direction.

Additional pressure upon the stock I9 and adjustment of the amount or length of stock fed is also provided for. The means for providing additional pressure includes a screw-threaded rod I35 having its lower end screw-threaded into the base I22 and which extends upwardly through suitable slots I38 formed in the outer end I31 of the arm III of the part II8. A spring I38 is provided to react between the upper surface of the arm H1 and an adjusting nut I39 screwthreaded on the upper end of the rod I35. Adjustment of the nut I39 on the rod I35 varies the tension of the spring I38 to vary additional pressure imposed on the stock I9 by the member III.

The arm H1 is bifurcated at its outer'end I31 to provide a cross-slot I in which an adjusting nut I42, also screw-threaded upon the rod I35, is disposed. Adjustment of the nut I42 upon the rod I35 varies the length of feedof the stock I9. For instance screwing down on the nut I42 will slightly lengthen the length of stock fed while screwing up thereon will slightly shorten the length of stock fed. By this arrangement the length of stock being fed may be finely varied while the machine is operating to insure proper operation of the tools thereon.

As will be readily ascertained from the above description of mechanisms embodying the features and principles of this invention, stock feeding mechanism is provided which is particularly efiicient and practical in use. The provision of the

clamp plates

33 and 34 between which the stock I9 is led, before it reaches the rollers 3| and 32, securely grips the stock I9 to prevent it being drawn backwardly or pushed forwardly due to any movement of the coil of stock 2| or slight,

back creeping of the stock due to its engagement with the lower roller 32 as this roller is rocked backwardiy during the up-stroke of the arm 28.

Positive stopping of the feed of the stock I9 in proper position is insured at the end of its feed and while gripped by the rollers 3I and 32, by the rollers 8| and 82, or by the member II I and the roller I25, due to the crank-knuckle 24 being at the low point in its rotation with the crankshaft I2, continued movement of the arm 28, rack 9|, or arm III, immediately releasing the stock as above described. Positive starting of the feeding action is likewise insured due to the crankknuckle 24 being at the high point in its rotation with the crank-shaft I2. A plurality-of points of adjustment of the pressure applied to the stock are provided, all capable of being made while the machine is in operation, for instance, by adjustment of the brake bands 88, 91, or I32, and

by adjustment of the nuts 88 and 81 or nut I38. The length of stock fed by the mechanisms shown may be coarsely varied by adjustment of the crank-knuckle. 24 on the slide 25, and finely varied by the adjustment of the nuts 12, the screws 81, or the nut I43, the latter adjustment of nuts 12, screws 81, or nut I43, being made possible while the press is operating.

While there has been shown herein three forms of mechanisms in which the features and principles of this invention may be embodied, it will be understood that the same may be embodied in other forms without departing from the spirit or essential attributes thereof, and it is therefore desired that the present embodiments be considered in all respects as illustrative and not restrictive, reference being had to the claims rather than to the foregoing description to indicate the scope of the invention.

Having thus fully described the invention, what is claimed as new and for which it is desired to secure Letters Patent, is:

1. In stock feeding mechanism, cooperating ing movable toward the other member to grip the stock therebetween and adapted to feed stock along between said members when so moved and the stock is gripped between and by said members, a first means to cause said movable member to so move in stock feeding direction, and a second means actuated by the actuation of said first means to resist feeding movement of said movable member and to move it toward the other member to grip the. stock therebetween before feeding the same.

2. In stock feeding mechanism, cooperating rockable members adapted to receive stock between the opposing surfaces thereof, a first means to move one of said members toward the other to grip stock therebetween, and a second means to actuate said first means and to rock one of said members to feed the stock gripped between the members. 3. In stock feeding mechanism, cooperating rockable members adapted to receive stock between the opposing surfaces thereof, a first means to rock a first one of said members, and a second means to resist the actuation of the first means to cause the first one of the members to move toward the other member to grip stock therebetween.

4. In a stock feeding mechanism in accordance with claim 3 and in which means is provided to vary the actuation resisting action of the said second means.

-5. In stock feeding mechanism in accordance with claim 8 and in which means is provided to resiliently press one Of said members toward the other.

6. In a stock feeding mechanism in accordance with claim 3 and in which connecting means is provided between the actuation resisting means, and the member moved thereby toward the other member, to press said moved' member toward the other member.

'7. In stock feeding mechanism, cooperating rockable members, means to rock a first one of said members, driving connections between the first member and a second one of said members; to rock the latter in timed relation with the rock-' ing movement of the first member, one of said members being movable toward and away from the other to first grip and then release stock disposed therebetween, and brake means acting on the movable member to resist rocking movement thereof to move it toward the other member when said members are rocked in one direction and to move it away from theother member when the said members are rocked in the other direction.

8. In stock feeding mechanism in accordance with claim 7 and in which means is providesd'to adjust the braking action of said brake means, and means is provided to adjustably limit the movement of the movable member away from the other member.

9. In stock feeding mechanism, a first rockable member journaled in fixed bearings, a second rockable member journaled in movable bearings, means to rock said second member, and means actuated by the rocking mov ment of said second member to move the movab e bearing and thus move the second member toward the first member to grip stock between the members.

10. In stock feeding mechanism in accordance with claim 9 and in which the means to move the movable bearings includes a brake acting on the second member to resist rocking movement thereof.

11. In stock feeding mechanism in accordance with claim 9 and in which the means to move the movable bearings includes a brake acting on the second member to resist rocking movement thereof, and means connecting the brake means to the second member to press it toward the first member.

12. In stock feeding mechanism, cooperatmg lockable-members adapted to receive stock and to feed it therebetween, and means to move one of said members toward the other including, means to rock both of the members, means rotatively driven by said rocking means, and brake means acting on said driven means to resist its rotative movement and through it the rocking movement of said members.

13. In stock feeding mechanism in accordance with claim 12 and in which the brake means comprises a brake drum operably connected to said driven means, and a brake band anchored to one of said rockable member to press the same tor feed it therebetween, means to rock said members in unison, and means to move a first one of said members toward and away from the second one including means driven by said rocking means, and brake means acting on said driven means to resist it movement in one direction to move the first member away from the second member and its movement in the other direction to move the first member toward the second member.

15. In stock feeding mechanism in accordance with claim 14 and in which the brake means includes a brake drum connected to the driven means, and an anchored brake band acting on the brake drum.

16. In stock feeding mechanism in accordance with claim 14 and in whichthe brake means includes a brake drum connected to the driven means, and a brake band acting on the brake drum and being anchored to the movable first member to press the same toward the second member when said brake means acts to resist the movement of said driven means in the direction causing movement of the first member toward the second member.

17. In stock feeding mechanism in accordance with claim 14 and in which the brake means is adjustable, and other adjustable means is provided to resiliently press the members together.

18. In stock feeding mechanism in accordance with claim 14 and in which the brake means isadjustable, and adjustable means is provided to limit the movement of the movable first member away from the second member.

19. In stock feeding mechanism, a pair of cooperating members between which stock is received to be gripped and fed thereby, a reciprocable member connected to a first one of said members to rock it forwardly and backwardly, the first member being mounted for movement toward and away from the other member when its rocking movement is resisted, a stationary brake drum, a brake band connected to said first member, and operably associated with said brake drum to resist rocking movement of said first member in one direction to move it toward the other member and in the other direction to move it away from the other member.

20. In stock feeding mechanism, cooperating members between which stock is received to be gripped and fed along, a first of said members being mounted for rocking movement forwardly and rearwardly and for movement toward and away from the other member, means to resist the rocking movement of the first member to move it in respect to the other member, and common -means to rock the first member and to actuate the said movement resisting means.

JAMES L. GH'FEN.