US2362238A - Glue spreader, surface coater, and the like - Google Patents

Description

NOV. 7, 1944. 5 BLACK ET AL 2,362,238

GLUE SPREADERS, SURFACE COATERS, AND THE LIKE Filed Aug. '1, 1942 6 Sheets-Sheet l Ihvnfora JohHIEZBIQcK 3w NOV. 7, 1944. J 5 BLACK ETAL 2,362,238

GLUE SPREADERS, SURFACE COATERS, AND'THE LIKE Filed Aug. 1, 1942 6 Sheets-Sheet 2 Q :r n

70 7| J in Invenl'or's JbhnEIBlack 13c LROEeM'QS.

N 1944- J. E. BLACK ETAL 2,362,238

GLUE SPREADERS, SURFACE COATERS, AND THE IJIKE Filed Aug. 1, 1942 6 Sheets-Sheet 3 Inventor's: J'OhHE-IBIQcK 8:

Nov. 7, 1944. J. E. BLACK ET AL ,2

GLUE SPREADER-S, SURFACE COAT'ERS, AND THE LIKE Filed Aug. 1, 1942 s Sheets-Sheet 4 IrNenTofis: \TohnE'B lack, 3r

1944- J. E. BLACK ET AL GLUE SPREADERS', SURFACE COATERS, AND THE LIKE Filed Aug. 1, 1942 6 Sheets-Sheet 5 Tb oF (9 lnvenfo r5:

JohriEZfBlack 3r J. E. BLACK ET AL GLUE SPREADERS, SURFACE COATERS, AND THE LIKE Nov. 7, 1944.

Filed- Aug. 1, 1942 6 Sheets-Sheet 6 Invenror'sl hnElBiack 3 Patented Nov. 7, 1944 John E. Black and Robert Sl Black, Mendota, m.-

Application August 1, 1942, Serial No. 453,208

2 Claims. (01. 192-130) This invention has to do with improvements in glue spreaders, surface coaters, and the like. More particularly, the present invention has to do with improvements, of such machines of that type in which there are provided rolls between which the material is passed during treatment.

Generally there are provided a pair of such rolls, one above the other, and both rotating on horizontal parallel axes, the stockor material passing between these rolls while such stock lies in a generally horizontal plane. These rolls may be herein referred to as the .main or master rolls. They are supplied with the surface coating of glue or-other material to be transferred to the surfaces of the stock passing between such rolls; and for this purpose there are also generally rovided suitable "doctor rolls which lie parallel to the respective main rolls and horizontally displaced from said rolls a slight, but adjustable distance, so that the glue or other material to be supplied to the main rolls may be contained in a pocket above and between each main roll and its companion doctor roll. During operation the several rolls are rotated in such directions as to ensure passage of the sheet of stock horizontally between the main-rolls; and also to ensure proper transfer of the glue or other material from each pocket onto the surface of a main roll, being thereby carried around to the point or line of application of such glu or other material to the surface of the stock.

From the above it appears that a simple form of machine is one in which there are provided th two main rolls lying parallel to each other, one above the other, and also two doctorrolls, one lying in the horizontal plane of each of the main rolls, and one lying. to one side of the pair of main rolls, and the other lying to the other side of such pair of main rolls.

. Machines of the foregoing general type are disclosed in our co-pending application for Letters Patent-of the United States, Serial No. 391,324, filed May 1, 1941, and also herein illustrated and described. Such machines are frequently provided with means for adJusting the vertical separation between the two main rolls, one above the other, according to the thickness of the sheet stock to be passed between said ro1ls,but generally the distance of such separation is not more than a fraction of an inch, according to the thickness of such stock material. In case ofusing the rise in cas of entry ofabnormally thick ma-. 7

terial between such main rolls, but due to the weight of each main roll, and the provision of spring means to retain the uppermain roll in lowered position against a suitable adjustable stop, a large force is required to lift theupper -main roll, and thereby enlarge the separation between the main rolls, in case of emergency.

Likewise, means are sometimes provided for retaining each doctor roll in adjusted position with respect to its main roll, and under spring pressure, and with a very small clearance between a each main roll and its doctor roll, according to machine for surface coating veneer and the a like the separation is Ve y small, depending on e thickness of such veneer. Sometimes, also, provision is made for permitting the upper main roll to the thickness of the film of glue or other material to be surface coated on the stock, but in case of emergency a large force is required to shift such doctor roll laterally away from its main roll to enlarge the clearance between such rolls.

Generally, also, during the operation of such a machine there are stationed two operators, one at th in-feed side of the machine, and-the other at the out-delivery side thereof; the former operator starting each sheet of stock between the main rolls, and attending to the'feed of the stock; and the latter operator receiving the sheet stock' as it comes through between the main rolls, and attending to the disposition of the same as the operation is completed. It will be manifest that there is danger to the operator at .the in-feed side of the machine, due to possibility that he may have his hand or some portion of his body or clothing caught between the main rolls, which are rotating in such direction that they would tend to draw the hand or other object 'in between them; and there is danger to chine, clue to the possibility that he may have his hand or some object of clothing caught between the lower main roll and the companion doctor roll which are rotating in such directions as to tend to draw materials downwardly between them.

Thus it appears that with such double pair roll type of machine there is danger to both of the operators, due to the directions in which the rolls turn. T

It to be noted that when feeding and coating such thin stock as veneer and thelike,

it sometimes happens that a sheet of such stock will follow one"0f the main rolls after the veneer sheet has started to deliver between said rolls; and in such case such veneer sheet may either wrap itself around one of the main rolls, or may become jammed between the lower main roll and the corresponding doctor roll at the delivery side .jammed between the main roll and the doctor roll,

to catch the edge of the sheet and properly guide it to prevent such action. This is a very dangerous function, and especially so in case of tendency of such thin sheet to jam between the main and doctor rolls.

It is further noted that when a thin sheet such as a sheet of veneer becomes jammed between a main roll and its doctor roll, such veneer sheet generally breaks up and slivers thereof become lodged between said rolls, with damage to the rolls, and with the causingof much trouble in cleaning outthe space between the rolls. In this 7 connection, it is frequently the practice to surface the main rolls with rubber or neoprene, giving a yielding surface to such rolls, and in case,-

of such jamming as just mentioned much damage may be caused to such yieldable surface rolls, requiring resurfacing thereof, with attendant costs of such resurfacing, as well as the much more expensive loss of time in the use of the machine itself.

Heretofore various expedients have been devised to prevent the sheet of stock from following around the doctor roll. One such expedient comprises the {formation of circular: grooves 1 around the main rolls, such grooves being formed in the rubber or neoprene surface, or other yieldable surface; together with fingers which are mounted stationary and having their tips reaching into such grooves. Said finger tips are intended, when used,'to catch the edge of the outdelivering sheet, anddirect it away from the roll, 4

thus starting the sheet in proper fashion. How-: ever, it is found that such fingers, when used,

- frequently catch the rubber or yieldable surface, or globs of glue or other material form on the tips of such fingers, catching the edges of such grooves, and soon damaging the yieldable surface, requiring resurfacing thereof, with much expense, and with corresponding tying up of the machine during such work.

It is a principal object of the present invention to provide means at each side of the machine, both in -feeding side and delivery side, whereby the driving motor or other drive for the rolls may be immediately stopped in case of emergency;

such means. taking the form of rods or bars which extend lengthwise of the machine in position for ready engagement and pressure by the drive; but so that in case of great emergency a further pressure exerted on either of such bars will result in actual reversal of the driving motor so as to reverse the rolls and thereby release the sheet of stock or the hand or other part which may have become caught between the rolls.

In connection with the foregoing it is a further object of the invention to so arrange this protective device that it may readily be attached to machines which are already in service, and with little machine work of any kind on such machines, and without the need of any rebuilding thereof. In this connection it is a principal object of theinvention to make such provision for attachment to machines such as disclosed in the aforesaid application, Serial No. 391,324, as well as other similar machines.

It is a further principal object of the invention to make provision for the stoppage of the drive by the operator at the delivery or out-feed side of the machine, very quickly and certainly, in case the sheet coming through between the rolls should tend to wrap around either roll, or follow between the main roll and the doctor roll at that side: of the machine. By such provision much trouble and expense will be avoided, since at the instant that the operator at the out-feed side sees that the sheet is not being properly delivered he may stop the drive, even before any damage has been done.

In connection with this tendency of the thin sheet to not deliver properly, but to follow around one or the other roll, we wish to point out that sometimes it is necessary, in the case of sheets of excessive dimension transverse to the grain of the wood, to feed such sheets between the rolls with the grain parallel to the axis of roll rotation. In such case the tendency. of the sheet to operator at such side of the machine.- In this connectionv it is a further object of the invention to soplace and locate such bars that they may 7 60 be readily engaged by the hand, elbow or arm of the operator, and pressed thereby to caiise stoppage of the drive with great rapidity, and with exercise of smalliforce. Also, to" Pr vide such protection rods or bars at-both sides of the machine, so that either of the. operators may, in case of emergency. protect himself by emergency stoppageof the machine. and without the need of giving a signal to the vother operator for that pm i v direction of In connectionwith the fowl n8, it afiirther object of the invention to so arrange gencybarsthatwhenprenedeitheroneofthem will immediately bend and follow around the roll surface is exaggerated, and improper delivery frequently results. Sometimes this tendency is partly overcome by feed of the sheets on the bias, but still the tendency will persist to a greater or lesser degree. All such damages anddangers are prevented by ability to immediately stop the drive before damage may have occurred. These veneer sheets are expensive, and sometimes are scant, so that prevention of such damage is very important.

It is a further object of the invention to make provision in the form of protective plates and the like, for reducing the possibility of the hand 'or other part or object from finding its way between the rolls. In' this connection, it is an object to provide a protective plate at the in-feed side-of the machine whereby the clearance between the doctor roll and such plate at that side is made so small that it is very difficult for the hand or other object to reach the space between the main rolls. Also, in this connection, to so arrange this plate and its location, that the tendency of the doctor roll at the in-feed side, will be to resist such insertion of the hand or other object. This is because of the direction of rotation of such doctor roll with reference to the insertion of the hand or other object.

.' Likewme, in connection with the out-feed side of the machine it is an object of the invention to make provision for larg ly preventing the insertion of the or other object, between the lower main roll and the companion doctor roll at the out-feed side of the machine. ralso tfprotect thespacebetweentheimpermainrollandthe win mmemt mo eomponiondoctorrollao-ostolarpdypraventinaaeaass sertion of the hand or other object at such location.

Other objects and uses of the invention will appear from a detailed description of the same, which consists in the features of construction, and combinations of parts hereinafter described and claimed.

In the drawings:

Figure 1 shows a side elevation of a machine embodying the features of our present invention,

onto the surfaces of the main rolls. Such adjustments may be eflected in any and all vertical adjustments of the end plates 28 and 29; and the details of these constructions are not shown herein. i

Furthermore, the mountings or joumallings of the several parts just above referred to, and their constructions, are such that for any given adjustment or setting of the main rolls vertically (by looking towards the in-feed side of the machine;

. Figure 2 shows a side elevation corresponding to Figure, l, but showing the out feed or delivery side of the machine;

plate for attachment to one end stand ofthe machine, to carry the emergency control bars, and to carry the controlling switch and the connectionsof the control bars thereto,'and connecting parts;

Figure 7 shows an edge view corresponding to Figure 6;

Figure 8 shows a fragmentary planview of portions of thetop set of main and-doctor rolls, together with a protecting screen or shield set above said rolls; and

Figure 9 shows a cross-section taken on the line 9-9 of Figure 8, looking in the direction of the arrows. J

We have shown the features of our present invention embodied in a four roll machine, including a pair of main rolls placed one directly above the other, both rotating on horizontal axes; and also including companion doctor rolls placed alongside said main rolls and in horizontal alignment therewith. Thus, in Figure 9, in

I particular, there are the upper and lower; main rolls and 2|, rotating on the axes 22 and 23; and the companion doctor rolls 24 and 25, rotating on the axes 26 and 21. These rolls are suitably journalled in or adjacent to the end plates such as 28 (for the upper set) and 29 (for the lower set), there being corresponding end plates at both ends of the machine. The

machine illustrated also. includes the end stands 30and 3| for the drive end and the opposite end,

respectively; and the-end plates just above referred to are 'suitably mounted with respect to these end stands. Such mountings are of a nature permitting vertical adjustments of the upper-plates 28 by means of the caps 32 on top of the end stands, thereby adjusting the vertical position of the upper set ,of rolls 2024; and'such mountings for the lower end plates 23 are of a nature to permit vertical adjustment-thereofwith respect to the. end stands, such vertical adjustments being effected by means of the hand wheel a; and shaft 34, through the means of suitable connections, not shown in detail herein. Fur! thermore, the mountings or journallings of the doctor rolls are such that said rolls may be adjusted back and forth with respect to the respective main rolls by. means of the hand wheels or knobs 33, with very small and accurate adjustments to thus accurately adjust the clearances between the main and doctor rolls for adjust ment of the thickness of thefilm beingtaken the hand wheel and shaft arrangement 33-34 for the lower main roll, and by the caps 32 for the upper main roll) to thereby adjust the spac- .onto the surface of such main roll, suchsetting is so made that by exertion of considerable force such doctor roll may be forced back slightly from itssetting, against spring force; but in this case, also, the exertion of considerable force is required to effect such separation. I

A suitable driving motor 38 is provided, generally mounted on the end stand 30, and carried by a bracket 3'lthereon; such driving motor being connected to the shafts or. driving axes for the several rolls by connections and instrumentalities not herein shown in detail. Such connections herein shown, however, include the chain 38 riding over the sprockets 39 and 40; andthereare also provided suitable driving connections between each main-roll and its doctor roll so that said rolls are driven in proper harmony. All such connections are so' made that for normal forward drive the rolls will rotate as shown by the arrows in Figure 9, for the passage of stock between the main rolls in the direction of'the arrow ll-in Figure 9. It is noted in that figure that upon introducing a sheet of stock between said main rolls there is a tendency to draw same towards and between said rolls, so that the hand I I or other part or object of the operator at that in-feed side of the machine might be drawn between said rolls and injured thereby, or the machine become' clogged or injured by such object.

It is also noted that during such normal operation of the rolls the directions of the main roll 20 and its doctor roll 24 are such that an object above said rolls might be drawn down between them with. similar damage or injury. Likewise it is noted that the normal directions of rotation of the main roll 2| and its doctor, roll 25 are such that an object above said rolls might be drawn down between them with similar damage or injury. This latter condition exists at the out-feed side of the machine and at-the location of the operator there stationed.

Now all of the constructions and features previously referred to in the foregoing description exist and are shown in previous machines; and

v the details thereof are fully shown and described in our co-pen i g application, Serial No, 391,324,-

filed May 1, 1941; so for this and otherreasons we deem it unnecessary to illustrate and describe f said details herein.

Generally the main rolls in anti 2| are surfaced with rubber or neoprene or other suitable yieldable material, either plain or grooved, and the with similar results.

glue or other material being applied by said rolls is carried-in the pockets above and between the main rolls and their doctor rolls, as shown at 42 and 43. The downward surface movement of Now when passing thin stock such as veneer sheets bttween the main rolls, it sometimes happens that such thin sheet tends to flex around the surface of one of the main rolls and follow such surface at the delivery side (generally this happens in the case of the lower main roll); and such tendency is aggravated when such sheet of stock is fed between the rolls with its grain parallel to the axis of rotation. Such tendency is further aggravated by the stickiness of the film of material on the roll surface, and being applied to the surface of the sheet of stock. When such unintended action occ s such sheet of veneer or stock generally ante between the lower main roll 2| and its doctor roll 25, with corresponding damage to such main roll, destruction of such sheet of stock, damage to the rubber or other yieldable surface of the main roll, and

general tying up of the operations and other damage to the machine.

such controls working through a common connection to the motor or other control.

W provide a bracket 44 on one of the and stands, preferably the stand 30-at the motor drive end; and such bracket 44 carries a plate 55 on whichis mounted the control switch 46. Said control switch has therein suitable contacts for forward," off, and for reverse, generally with the control lever 4'! rockingly carried in the switch, as well shown in Figures 3, 6 and 7. The off positionis the central position, with forward above it, and with reverse below it, as shown by the designations in Figure 6. Said bracket 44 also carries the bell-cranks 48 and Gil, pivoted thereon, at the points 60 and and the horizontal arms of these bell-cranks are connected by the links 52 and 53 to the switch arm The operator at the out-feed side of the machine watches the edge ofthe sheet of stock as it appears from between the rolls, and in case of any tendency of such edge to follow the main roll he should catch the edge of the sheet of stock and prevent it from following around the roll; but in so doing there is great danger that he may have his hand or finger or some object caught between the main roll 2| and its doctor roll 25. Such danger and such damage to the machine and to the stock itself may be prevented by suddenly stopping the machine by a suitable action of the operator at that out-feed side of the machine; and it is animportant object and feature of our present invention to make provision for such stoppage, or even for actual reversal of the machine in such case.

Heretofore it has sometimes also been the practice to provide circular grooves in the surface of the yieldable surfacing on the main rolls, and to provide fingers reaching into such grooves to catch the edge of the stock arriving from between the main rolls; but such fingers, when used, frequentl become bent or deformed so that they make actual contact with the "rubber or other surface, damaging the same and requiring resurfacing thereof; or sometimes globs of glue or material will adhere to the points of such fingers At the in-fed side of the machine there is, as

'hertofore shown, danger to the operator at that side of the machine, in case he should find it necessary to reach to a point close. to the approaclfing surfaces of the main rolls 20 and 2|. Therefore, it is desirable to make provision for emergency stoppage or even for reversal of the drive,

in case of such emergencies at the in-feed side.

It is not sufficient to make provision for such stoppage or reversal from one side only, of the machine, since in case of emergency occurring at the otherside it would be necessary to call out to the operator atisuch other side, with consequent delays, and with possible failure to hear or properly react. It is therefore an important featfire and object of our present invention to ,make provision for such stoppage or reversal in emergency from either side of the machine, both 41 by the pin 54, so that rocking of either bellcrank will control the switch arm. Suitable arms 55 and 56 are also pivoted to the other end stand 3 I, or to a plate carried thereby; and control rods 5i and 58, for the in-feed and out-feed sides of the machine extend-between the bracketarms 4855 and 4956, respectively, so that movements of these control rods serve to actuate the switch arm 41 as will be readily apparent. Furthermore, it will be seen that pressure against either of these control rods 51 or 58, moving the same towards the machine, will move the switch arm 41 downwardly, to either shut off said switch, or, by full movement of either of said rods, to shift the switch arm 41 fully down, to reverse the switch connections. If desired, the control switch itself may be provided with suitable means tending to retain the switch in any position to which it may be moved, so that a slight force must be exerted to shift said switch from such position to another position. Thus, when in the forward position, ,a slight force is needed to shift said am 41 to the off position, and when in such ofl position a slight force is needed to shift said switch to the reverse position. These forces are, however, slight.

It will be understood that this switch 46 may be of any suitable construction, and that the connections thereof to the motor 36 should be such as to ensure proper current supplies onstoppages, according to the switch positions; and we do not deem it necessary to illustrate the same in detail herein, as such arrangements are well known and understood in the arts.

The bracket plate 44 also carries sfiitablestop pins 59 and 60, which may be adjusted, and which serve to limit the rocking movementspf the bellcranks. These pins are set to limit movemen s in the forward and reverse" directions, respectively;

Now, generally the emergency/movement of 4 either of the rods 51 or as, should be only to the. off position, since it will generally be sufllcient or 58. In order to ensure, however, that such rod movement will ordinarily stop at the off position, we prefer to provide on the bracket 44 the spring pressed pin 6|, having the top plate 62 against which the bell-crank 48 will come to rest at the off position, said pin andplate 6l-62 being pressed up by the'spring 63 to a limited positor's hand or member be extended inwardly'iar tion determined by the plate or head 84 on the lower end of said pin I With this arrangement, when either of the rods 51 or 58 is suddenly moved towards the machine by either of the operators, such movement will stop at the 0135" position; but still, if desired, further pressure may be made against such rod 51 or 58, to shift it momentarily to the'revers e position, thereby causing reversal to occur as long as such extreme movement is intentionally maintained. It will be noted in this connection, that when stoppage only, is intended, such stoppage should continue for an indefinite time, once it has been caused, and until the machine is again intended to be brought into operation; but reversal should continue only for a very short interval, to release some object from between the rolls, so that such reversal should continue only as long as the rod is held in the fully: moved position, and against the force of the spring 63. Then when released the parts will be moved back, by such spring 63, to the ,ofi position where they will remain until the machine is again intentionally started.

Thus we have provided means to shift the control parts to the ofl position, leaving them in such position indefinitely, and until intentionally again moved to the-running position; together with means to shift said control parts to the "reverse position, but normally returning them to the "off" position when released. In this connection the following facts shouldalso be kept enough to become caught between the main rolls.

We have also shown a guard screen or plate 60 above the space between th upper set of rolls, -24, such screen or plate 68 being carried by suitable end brackets or the like mounted on theend plates 28 for the upper set of rolls. Thus this guard screen or plate 68 will always be main-v tained at the proper position relative to said upper set of rolls. If desired, suitable handles or the like, iilmay be provided for this guard so that it can be readily set into place or removed from position to gain access to said rolls.

We have also shown a series of fingers Ill, carried by longitudinally extending bars II, which in turn are carriedby the end plates 29 for the a lower set of rolls, said fingers being placed at the Ject of the combination of the main and doctor rolls is to make possible control of the thickness of the film of material taken onto the main rolls;

and in case of reversal of rotation such control below the doctor roll 24, and reacliing to a position close to the point of entry of the sheet of stock between the main rolls. This guard plate is conveniently carried by end flanges or brackets 66 which are secured to the end plates 29 for the lower set of rolls, so that such guard plate rises and falls with the vertical adjustments of such a lower set of rolls. Preferably the front edge 61 of such guard plate 65 is bent downwardly to provide'a protective edge. Such guard plate is located slightly beneath'the upper doctor roll 24, so that the hand-or other member of the operator a at the in-feed side of the machine cannot be ex- 1 tended inwardly far enough to reach the two mainrolls and become caught between them, except by a forceful insertion of such hand or-member.

Furthermore, it is noted that during such insertion of the handor member it will contact against therlower portion ofthe upper doctor roll, which is turning away from the point of entry between the main rolls; and thus it would tend to exert a out-feed side of the machine. The inner ends of these fingers are slightly pointed and are brought close to the surface of the lower main roll, 2 I and close to the point of exit of the sheet of treated stock from between the main rolls. These fingers, when provided, are intended to catch the delivering sheetof stock and ensure fingers or other members or partscaught between the lower set of rolls, which, it will be noted, are rotating in such directions as to tend to draw materials downwardly between them. Further protection in this connection, and at this point,

is afforded by means of the screen or the like,.

12 secured to the fingers 10, and suitably located to prevent access to the space immediately between the lower set of rolls.

If desired, additional control rods 13 and 14 may be provided at the in-feed and out-feed sides of the machine, carriedby bell-cranks 15 and I6 on the end stands, said end stands being suitably recessed, if necessary. to permit proper-operation of 'these parts; and the horizontal arms of such bell-cranks may be connected to the bell- cranks 48 and 49 by means of links 11 and 18 as shown. By this means the emergency operations may be effected by pressuresagainst these supplemental control rods and in manner and with results and functions. similar to those already explained herein. Thesev supplemental control rods, when used, may be located at a height convenient for actuation by; the operators knee or lower limbs, thereby affording supplemental protection if desired.

While we have herein shown and described only certain embodiments of the features of our present invention, still we do not intend to limit ourselves thereto, except as we may do so in the claims to follow. a

We claim:

1. In a surface coater, the combination with a Y alignment with each main roll, together with connections between all said rolls to ensure rotation *of the main rollsin opposite directions androtaforce against such insertion of such hand. For 7 all of the above reasons it will be evident that only by an intentional movement can the operation of each main roll and its doctor roll in op- Posite directions, and a driving motor for all said rolls, of a control switch for said driving motor,

said switch a central off. position, and

also having forward and reverse positions at opposite sides of said off position, of a horizontally extending control bar along each side of the machine, means to support both said control bars for movement back and forth towards and from each other and towards and from the central portion of the machine, interconnections between said bars to ensure movement of said bars towards or from each other simultaneously,

and connections between said bars and said switch effective to ensure switch forward closing posiof said bars and switch device from the switch off towards the switch reverse position, sub-' stantially as described.

2. In a surface coater, the combination with a pair main rolls located in vertical alignment with each other, and a doctor roll in horizontal alignment with each main roll, together with connections between all said rolls to ensure rotation of the main rolls in opposite directions and rotation of each main roll and its doctor roll in opposite directions, and a driving motor for all said rolls, of a control switch for said driving motor, said switch having a central ofi position, and also having "forward and reverse positions at opposite sides of said off position, of a horizontally extending control bar along each side of the machine, means to support both said control bars for movement back and forth towards and from each other and towards and from the central portion .of the machine, interconnections between said bars to ensure movement of said bars towards or from each other simultaneously, and connections between said bars and said switch effective to ensure switch forward closing position when the bars are moved farthest away from each other, and to ensure switch "off positioning when the bars are moved partially towards each other, and to ensure switch "reverse positioning when the bars are moved closest to each other, substantially as described.

JOHN E. BLACK. ROBERT S. BLACK.

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