US2531837A - Safety guard for presses - Google Patents

Description

Nov. 28, 1950 a. F. BEE'BME SAFETY GUARD FOR PRESSES 2 Sheets-Sheet 1 Filed Nov. 2, 1948 INVENTOR. BEER BE FBEEBE T TORNE Y Patented Nov. 28, 1950 UNITED STATES PATENT OFFICE 2,531,837 SAFETY GUARD roa PRESSES George F. Beebe, Waterbury, Conn.

Application November 2, 1948, Serial N 0. 58,000 '1 Claims. (01.192 13?) This invention relates to new and useful improvements in safety devices and has particular relation to a guard for machines of the type including a vertically movable plunger although, as herein disclosed, the guard is specifically for a foot operated type of press.

An object of the invention is .to provide a guard for and in a machine of the character indicated and including a feeler means movable in advance of the machine tool and a lock means for positively locking the machine plunger against downward movement, the former being interconnected with the latter in such a manner as to bring about locking of the plunger against complete downward movement or a complete downward stroke on said feeler means contacting an object, as the hand or finger of an operator, short of its full movement or its movement to which it is adapted in the usual safe operation of the machine.

Another object is to provide for and in a machine a safety guard means movable downwardly by gravity in advance of the machine plunger and upwardly by the machine plunger on return movement of the latter in combination with means under the control of said feeler means to cause stoppage of downward movement of the plunger on said feeler means engaging an object short of its normal full downward movement.

A further and more specific object is to provide in a machine including a head having a vertical way therein and a punch carrying plunger reciprocable in said way, a block rigidly attached to said plunger and projecting forwardly from said way, a mounting plate fixed to said head at one side of said way, a locking cam pivoted to said plate for movement into and out of the path of movement of said block, a pair of vertically spaced a'rms pivoted each at one end to said plate, a carrier plate spaced horizontally from said mounting plate, means pivoting the other ends of said arms to said carrier plate in the same spaced relation as the first mentioned ends of the arms are pivoted to the mounting plate whereby a pantograph-like structure is provided in which the carrier plate is movable in substantially parallel relation with the mounting plate, a feeler bar mounted on said carrier'plate and extending downwardly therefrom said plunger, means on one of said arms and having a pin and slot connection with said cam for moving the latter to and from the path of said block to release said plunger for downward movement and to lock it against downward movement, and a connection between one of said arms and said.

arms move about the pivots at their first men-. tioned ends and said cam is moved out of the path of movement of said plunger carried block and whereby as said plunger and block move upwardly on return movement of these parts said carrier plate and feeler rod are returned to their normal positions as the arms are rocked back.

on the pivots at their first mentioned ends and on predetermined movement of one such arm the pin and slot connection between its extension and the cam brings the latter back into the path of downward movement of said block. 7

Other objects and advantages of the invention will become apparent from a consideration of the following detailed description taken in connection with the accompanying drawings wherein a satisfactory embodiment of the invention is shown. However, it is to be understood that the invention is not limited to the details disclosed but includes all such variations and modifications as fall within the spirit of the invention and the scope of the appended claims.

In the drawings:

Fig. l is a side elevational view showing a foot press equipped with the safety means or guard of the invention;

Fig. 2 is a front elevational viewof said press,

the view being taken as looking from the right in Fig. 1;

Fig. 3 is a front elevational View on a larger showing the parts as when the press plunger has been arrested or locked due to engagement of the fingers of an operator by the feeler device of the present safety means or guard;

Fig. 6 is a somewhat similar view showing the relation of the parts at the limit of normal downward movement of the press plunger and punch; and

Fig. '7 is an enlarged front elevational view of certain. of the parts shown in Fig. 5.

Referring in detail to the drawings, a kicker 011' foot operated type of press is shown and is generally designated l0. Such press comprises a base H supporting an upright l2, the upper forward portion of which is'laterally enlarged as at 13- providing a, head. Such headis recessed in its forward face and in opposite edge portions of said recess are located guides I4 and I5 having V-shaped ways I6 and I1 therein and which ways are in opposing relation. The guide I5 is secured in place as by a series of bolts I8 while the guide I4 is also secured in place by three bolts, one of which, designated I9, passes through the upper portion of the guide and the other two of which are designated and pass not only through the guide but also through a mounting plate 2 I, the purpose of which will later be set forth. All of these bolts are threaded into the head portion of the upright I3, as best shown in Fig. 4.

Vertically slidable in the ways It and I1 of the guides I4 and I5 is a plunger 22 adapted in its lower end to mount a punch or other tool 23, depending on the job to be performed. As best shown in Fig. 4, the plunger 22 projects forwardly out of the guide way provided for it and as shown in Figs. 1 and 2, at its upper end, the plunger has a rearward extension or projection 24 through which is threaded .a screw 25 comprising an adjustablestop for limiting downward movement of the plunger with respect to the above mentioned head formed on the upper portion of the upright I2.

A tread1e'26 isintegral with or otherwise made rigid with an arm 21 shown as having its upper portion curved forwardly as at 28. Inwardly.

of its upper end, arm 21 is pivotally mounted. at 29 on the upright I2 and then the forward .end of said arm is, by means of a pin orthe like 30, secured to the plunger 22. This forward end of arm 21 I have designated 3 I and it will. be noted that the same passes through the plunger-22 as well. as being secured to the latterby the pin or other pivot 30. With this construction it will be understood, especially with reference to Fig. 1, that on the treadle 26 being rocked downwardly and rearwardly, the arm 21 turns on a pivot .29 whereby the forwardend 3| of said arm moves downwardly carrying the plunger 22 with it.

Downward movement of the plunger will be limited by the screw 25 and/or by the .punch 23 engagin or completing its work. In this connection, a die holder or work supportin block or the like 32 is shown as secured to the upper side of base II by machine screws 33, such die holder or work support being located beneath the punch 23. Base H is shown as in its opposite edges provided with openings or channels 34 for the passage of clamps or clampbolts for anchoring the press to anysuitable support. The press, as thus far described, is old and well known and is disclosed here in order that the application and operation of my guard or safety device may be better understood- Such guard or safety device includes the mounting plate 2I previously mentioned. A pivot means. 35 piv'otally secures one end of an arm of link 36 to the mounting plate 2|,whilea pivot means 31 pivotally secures the other end of said arm or link to a lower portion of a carrier plate 38.. Fixed to this carrier plate, .inany suitable manner, as by means of a screw 39 is a clamp 40 through which passes a vertically disposed feeler rod 4|. Clearly, on loosening of the screw 39 such feeler rod may be adjusted vertically through the clamp 40 and thereafter on tight- "is also pivoted for free movement.

means 42, here disclosed as a U-shaped means, the arms of which straddle the punch 23. The position of the U-shaped means is controlled by a lock nut 43 adjustable on the lower portion of said feeler rod 4I although, generally speaking, any adjustment made and involvin the feeler rod is made on loosening and thereafter tightening of the clamp 40 as above set forth.

A second arm 44 is pivotally mounted on the plate 2| by a pivot means 45 located in vertically spaced aligned relation with the pivot means 35. Also, a pivot means 46 pivotally secures the other end of the arm 44 to the carrier plate 38 in aligned vertically spaced relation to the pivot means-31. Thus, it will be seen that a pantograph-like structure is formed.

. A notch or recess 41 is formed opening through the forward face and the inner edge of the mounting plate 2| and such notch or recess is of a size and shape to wholly or substantially wholly receive a cam 48 when such cam is in unlocked or released position, as shown in Fig. 6. This .camis mounted on a pivot 45 and includes an upper curved or arcuate surface 50. Additionally, rigid with the cam and extending forwardly therefrom is a pin 5I projecting into or through aslot 52 in a plate-like extension 53 of the arm44. vAs here shown, this plate-like extension and-the .arm 44 are all blanked or otherwise formedfrom a single piece of metal. Slot52'is somewhat L-shaped .and includes a verticaltoe-like portion 54 as well as an arcuate portion55.

.In additionto the extension53 which projects from .theunder .orlower side of arm 44, thereis integral .with such arm and projecting from the upper side or-edge thereof, adjacent the .end mounted on the pivot45, a second extension 55 carrying a pin 51 projecting at the inner sideof said extension 56. This projecting portion of the pin cooperates with the horizontal surface 59 atone upper corner of a locking plate 611. secured to the forward side or face of the plunger 22 asby machine screws 6|. One lower corner of this plate 60 is cutaway providing an arcuate surface 62 on the same length radius as and. for cooperation with the curved surface 50 of thecam 48,as will be set forth.

When. mounting thepresent guard or-safety device on the press In, it is preferred to remove the two screws which normally occupy the position of the screws-- 20 and then locate the mountingplate by aligning holes in it with the screw holes in the guide I4 and then-employing the longer bolts 20 to secure this mounting plate in place. The lock plated!) is positioned on the plunger .22 in accordance with the location of the mounting plate 2|- As-this descriptionproceeds, it willtbecome apparent that the lockplate E0 is butaportion rigid with the plunger 22 and but for inconvenience and expense in manufactureand-assembly of a new press could be anintegral part of the plunger of such new press.

The above described pantograph-like means including the arms Y36 and 44 and the carrying plate and the feeler mechanism mounted on. the latter-are all adapted for pantograph-like movement .on rocking of the arms about the respective pivot means 35 and 45. The cam 48 since the stud or-pin 51 is.rigid withthe arm extension 56, when the plunger 22 is moved toward itsreturn or upper position, its lower surface 59 engaging the extension of pin '51 carries the same upwardly thereby througntheextension 56. rockv 5.1 ing the arm 44 in a clockwise direction whereby said arm is swung upwardly, as from any of the positions of Figs. 5, 6 and 7 to the position of Figs. 2 and 3.

This arm being attached to the carrier plate and through its connection by pivot 31 with arm 36 carries said arm upwardly. Also, this de--- scribed upward movement of the plate 38 results in upward or return movement of the feeler rod 4|. turn movement of the plunger 22, the parts of the present guard or safety device are given a return movement. Also, it isnoted that since at the end of any return movement the extension of pin 51 will be in engagement with the lock block 60, the parts of the safety device will be held in their upper or return or normal positions.

In connection with this matter of the return of the parts by the plunger 22 on return movement of the latter, it is noted that a channel-or groove'or elongated corner notch 58 is provided in the forward corner of the upper inner edge of the mounting plate 2|. The right hand edge of the lock plate 60 is adjacent this inner edge of the mounting plate 2|. Also, the projecting portion of pin 5'! is of a diameter to be received in the notch 58 as seen in Figs. 2 and 3. Therefore, on the return movement of the plunger 22, the lock plate 88 carried by said plunger through its portion 59 engages and raises the pin and the other parts of the safety device as previously described. However, since the raising movements of the guard parts includes a swinging movement of arm 44 on pivot 45, the pin 51 moves on an arc upwardly and to the right as the machine is shown in front elevation. The parts are movable sufficiently to have the projecting portion of the pin move entirely into the notch 58. This allows for excessive upward movement of the plunger 22 and lock plate 60 without damage to the pin 57 or any other part. When any such movement occurs, the pin will be held by a side or vertical edge of plate 60, rather than by a horizontal or top edge of the latter.

The mentioned return or upper positions are as especially shown in Figs. 2 and 3. There it will be noted that the pin 5| of the cam 48 is in the curved portion 55 of the slot 52 and that such cam is tilted partly out of its pocket or socket 4'! so as to partly project under the lock block 50. Specifically, a portion of the curved surface 5!) of the cam is below and in alignment with a portion of the curved surface 62 of the lock block. The slot portion 55 is shown as somewhat excessive in length to allow for a greater return movement of the plunger than that here illustrated should such return movement be desired.

'The plunger 22 being in its upper position, the operator will place a piece of work on the holder 32 and then operate the lever 21 to depress the plunger and bring the punch 23 against the Thus, it will be understood that on any rework. At the start of this movement, the parts when loading the press. However; as the plunger 22 starts downwardly and the safety assembly is released, it falls ahead of the punch so that the feeler device 42 moves to a position below the lower end of the punch. Also, as such safety device rocks about the pivots 35 and 45, the extension 53 of the arm 44 is rocked as fromthe position of Fig. 3 to thatof Fig. 6. As this occurs, the toe portion '54'of the slot 52 comes opposite thepin 5| and the wall portion 63 of said slot engages the pin and pressing on the latter, as the movement of the extension 53 continues, forces the pin and thereby the cam 48 tomove in a clockwise direction about the pivot 49 of the cam (during such movement, as the cam moves on its pivot, the pin 5| enters the slot portion 54) so that the cam is moved from its locking position of Fig. 3 to its released position of Fig. 6.

In the former of these positions, it will be seen that the cam is projecting into the path of movement of the lock blocl; -68 while in the'latter of these positions the cam is wholly or substantially wholly within the socket 41 and clear of the path of movement of the said lock block. Thus, the lock block and therefore the plunger 22 may be given a complete downward movement to have the punch 23 perform its desired function. At this time, the feeler rod 4| is moved all the way down but since there was no obstruction has not performed any function. Now, on release of the treadle 26, the plunger 22 is returned to its upper or normal position and by: engagement of the surface or shoulder 59 of the lock block 68 with the pin 51 has brought about return movement of the various parts of the present safety device or guard.

The above describes the normal operation of the press or the operation of the press when the operator has been careful to keep his hands or fingers from any dangerous position with respect to the punch 23. Fig. 5 illustrates what occurs when the operator carelessly or otherwise has his fingers in a position to be injured. In such view, a portion of the operators hand is suggested at 84. According to the disclosure in Fig.

5, the plunger '22 has started downwardly, the surface 59 of the lock block 60 has moved downwardly from under the pin 51 and the various elements of the present safety device (which elements include the arms 36 and 44 and the carrier plate 38) have also started downwardly. However, the feeler 42 could not complete its downward movement and moving ahead of the punch 23 has engaged the fingers of the hand 64. It is to be borne in mind that this safety device including the feeler 42 moves downwardly only under the influence of gravity. Thus, there is not enough weight or momentum to injure the operators hand or fingers.

arrested, the carrier plate 38 is held against'further downward movement and thus the arms 36 and 44 (and at this time we are particularly concerned with the latter) have had but limited movements about their pivots 35 and 45, respectively. Since movement of the arm 44 has been limited, its extension 53 has had limited movement and has not moved sufiiciently to pick up the pin 5| and shift it and the cam 48 about thestill positioned with a portion of its arcuate surface 58 in the path of movement of the arcuate surface 62 of the lock block and has engagement Downward movement of the feeler having been I With such latter ,surtace. Therefore, the cam is presenting. a positive. lock preventing movement of. the plunger 22 downwardly for any distance greater than that illustrated. The distance between the arcuate surfaces. 50' and 62, when the parts are in their upper positions or their normal positions, represents the length of. movement which'may be imparted to the punch 23 following'engagement of anobject by'the feeler device 42. Usually I'construct the parts so as to have downward movement of the punch: 23 stopped in about one quarter of :an inch of movement following engagement of the fingers orthe like by the: feeler device 42.

When the. treadle is released with the parts positioned as in Fig. 5-, the plunger 22 is free to move upwardly and since it moves the lock block 68, the latter will engage pin 51 and. the. parts of the present safety devicewill be carried upwardly. This has no particular efiecton the cam-48 since the longpart or portion '55 of the slot 52 provides for a rocking movement of thearm 44 and its extension 55 on the pivot 45 without any'binding against the pinil. The arcuate surfacesiD-and 62 being complemental: or on equal length radii, there'ls no tendency for one to cam the other aside whenthey come into contact.

When the plunger has been given the full movement, assuggested in Fig. 6, for the normal return of'the parts the surface. portion 85 of the toe portionil oi slotiz forcesthe pin 5| out of such toe portion. of the slot and into the long portion of the slot whereby the "extension 530i the. arm 44, swingingon the pivot 45, doesnot' bind or in- .any way tightly engage with the pin 5|.

Having thus setv forth the nature of my invention, what I. claim is:

.1. In a machine, a stationary head and a plunger mounted on said head for vertical reciprocating movement, .a lock platerigid with saidplunger and protecting at theiorward side of. said head, amounting plate on the forward side of saidhead-at one edge of said lock plate, said mounting plate having a notch opening through itsforward side and its inne-r'edge, a cam, means pivotally mounting said cam for movements between a position substantially wholly within saidnotch and out of the way of said lock plate and a. locking position projecting through the edge of'said'notch and into the path of movement of said lock plate, .a carrier plate movable vertically in a'plane forwardly of said lockplate, a pair of vertically spaced. parallel arms pivoted at their respective ends to said mounting plate and carrier plate, a vertical feeler rod; means securing said feeler rod to said carrier plate for vertical adjustmentrelative thereto, a feeler means on the lowerend ofsaid feelerrod, an extension-like part rigid with the upper of said arms: and having a slot therein including substantially right angularlyrelated portions,,a pin rigid with said cam:in spaced relation to the .pivotal mounting'of the cam and'extending through the open side of said notch and through said slot, said parts related whereby when said upper arm is in its upper position said pin is in the first portion of said slot and said cam is projecting through the edge of said notch into the pathof downward movement of. said locking plate to positivelylimit-downward movement of said plunger andwhereby when said upper arm is in its lowest position said i'eeler' means is in its lowest position and said extension like' part is positioned with said pin in thesecond portion of within said notch and clear of the-path of downward movement of said locking plate, a stud rigid with the upper of said arms and movable with the latter from av position'at a side of the path of movement; of said locking plate to a position in. such path and extending over the upperedge of the locking plate whereby as said plunger and plate-move downwardly saidstud is released and said arms, carrier plate and feeler rodgravitate'downwardly as said arms turn about the means pivoting them to the mounting plate and said feeler means .moves ahead of the plunger, andas said plungerand plate move upwardly the upper edge of the plate engages said stud and moves the same upwardly moving said arms in the opposite'direction on their mentioned pivots and raising the'feeler rod and means.

2. In a machine, a stationary head and a plunger mounted on said head'for vertical reciprocating movement, :a lock plate rigid with said plunger and projecting at the'forward side of said headya mounting plate on the'forward side o fisaid head. at one edge of said lock plate, said mountingplate having a'notch opening through its forward side and its inner-edge, a. cam, means pivotally' mounting saidcam. for movements between a position substantially wholly within said notch and out of the Way of said lock plate and a loeking'position projjecting'through the edge of said notch and into the path of movement of said lock'plate, a carrier plate movable vertically in a plane. forwardly of said lock plate, a pair of vertically spaced parallel arms pivoted at :their respective ends'to said mounting plate andcarrier plate, a vertical feeler'rod, means securing'said feeler rod to said carrier plate for vertical adjustment relative thereto, a feeler means. on the lower end of said feeler rod, an extension-like part rigid with the upper of said arms and having a slot "therein including substantially right angularly' related portions, a pin rigid with said cam in spaced relation to the pivotal mounting of the. cam and extending through an open side of said notchand through said slot, said parts related wherebywhen said upper arm is in its upper position said pin is in the first portion of said slot and said cam is projecting through the edge of said notch into the path of downward movement of said locking plate to positively limit downward movement of said plunger and whereby when said upper arm is in its lower position said feeler means is in its lower position and said-extension-like part is positioned with said pin in the second portion of said'slot and said cam is substantially wholly within said notch and clear of the path' of downward movement of said locking-plate, a stud rigid with the upper of said arms and movable with the latter from a position'at a side of thepath of-movement of said locking plate to a position in such path and extending over the upper edge of the locking plate whereby as said plunger and plate move downwardly said stud is released and said arms, carrierplate and feeler rod gravitate downwardly as said arms turnabout the means pivoting them to the mounting plate and said feeler means moves ahead of the plunger, as said plunger and plate move upwardly the upper edge of the plate engages said stud and moves the same upwardly movingsaid arms in theopposite direction on their mentioned pivots and-raising the feeler rod and means, and said feeler means adapted on engagement with an object during downward gravitational-movement of saidfeeler means to of said head, a mounting plate on the forward side of said head at one edge of said lock plate, a cam, means pivotally mounting said cam on said mounting plate for movements between a position projecting into the path of downward movement of said lock plate and a position clear of such path of movement, a carrier plate movable vertically in a plane forwardly of said lock plate, a pair of vertically spaced parallel arms pivoted at their respective ends to said mounting plate and carrier plate, a vertical feeler rod, means securing said feeler rod to said carrier plate for vertical adjustment relative thereto, a feeler means on the lower end of said feeler rod, an extension-like part rigid with the upper of said arms and having a slot therein including by When said upper arm is in its lowest position said feeler means is in its lowest position and said extension-like part is positioned with said pin in the second portion'of said slot and said cam is clear of the path of downward moveof said locking plate to a position in such path and extending over the upper edge of the locking plate whereby as said plunger and plate move downwardly said stud is released and said arms, carrier plate and feeler rod gravitate downwardly as said arms turn about the means pivoting them to the mounting plate and said feeler means moves ahead of the plunger, and as said plunger and plate move upwardly the upper edge of the plate engages said 'stud and moves the same upwardly moving said arms in the opposite direction on their mentioned pivots and raising the feeler rod and means.

4. In a machine, a stationary head and a plunger mounted on said head for vertical reciprocating movement, a lock plate rigid with said plunger and projecting at the forward side of said head, a mounting plate on the forward side of said head at one edge of said lock plate, a cam, means pivotally mounting said cam on said mounting plate for movements between a position projecting into the path of downward movement of said lock plate and a position clear of such path of movement, a carrier plate movable vertically in a plane forwardly of said lock plate, a pair of vertically spaced parallel arms pivoted at their respective ends to said mounting plate and carrier plate, a vertical feeler rod, means securing said feeler rOd to said carrier plate for vertical adjustment relative thereto, a feeler means on the lower end of said feeler rod, an extension-like part rigid with the upper of said arms and having a slot therein including substantially right angularly related portions, a pin rigid with said cam in spaced relation to the pivotal mounting of the cam and extending through said slot, said parts related whereby when said upper arm is in its upper position said pin is in the first portion of said slot and said cam is projecting into the path of downward movement of said locking plate to positively limit downward movement of said plunger and whereby when said upper arm is in its lowest position said feeler means is in its lowest position and said extension-like part is positioned with said pin in the second porton of said slot and said cam is clear of the path of downward movement-of saidlocking plate, a stud rigid with the upper of said arms and projecting rearwardly therefrom into the path of movement of said'lock plate whereby on upward movement of said plunger said stud is engaged by said plate and said carrier plate, arms and said feeler rod are moved upwardly as said arms swing on their pivotal mountings on the mounting plate. and whereby on downward movement of the plunger said stud is released and said arms and carrier plate gravitate downwardly as said arms pivot in the opposite direction, and said feeler means adapted 0n engagement with an object during downward movement of said feeler means to act through said feeler rod and maintain said carrier plate and arms against further movement in a direction to have the extension-like part of the upper arm move to receive the pin in the second portion of said slot whereby said plunger is locked against all but limited downward movement.

5. In a machine, a stationary head and a plunger mounted on said head for vertical reciprocating movement, a lock plate rigid with said plunger and projecting at the forward side of said head, a mounting plate on the forward side of said head at one edge of said lock plate, a cam, means pivotally mounting said cam on said mounting plate for movements between a position projecting into the path of downward movement of said lock plate and a position clear of such path of movement, a carrier plate movable vertically in a plane forwardly of said lock plate, a pair of vertically spaced parallel arms pivoted at their respective ends to said mounting plate and carrier plate, a vertical feeler rod, means securing said feeler rod to said carrier plate for vertical adjustment relative thereto, a feeler means on the lower end of said feeler rod, an extension-like part rigid with the upper of said arms and having a slot therein including sub stantially right angularly related portions, a pin rigid with said cam in spaced relation to the pivotal mounting of the cam and extending through said slot, said parts related whereby when said upper arm is in its upper position said pin is in the first portion of said slot and said cam is projecting into the path of downward movement of said locking plate to positively limit downward movement of said plunger and whereby when said upper arm is in its lowest position said feeler means is in its lowest position and said extension-like part is positioned with said pin in the second portion of said slot and said cam is clear of the path of downward movement of said locking plate, means whereby on its upward movement said plunger moves said arms, carrier plate and feeler means upwardly swinging said arms on their pivotal connections with the mounting plate and whereby on downward movement of the plunger said arms, carrier plate and feeler means are released to gravitate downwardly as said arms swing in the opposite direction, 'and'said i'eeler means adapted on engagement with an object during downward movement ofw-said f'eeler means to act through said feeler rod and maintain said carrier plate and arms against further movement in a direction to have theextension-liike part of the upper-arm move" to receive the pin in the second portion of said slot.

6. In a machine, a stationary head and a plunger mounted said head for vertical reciprocating movement, a lock plate rigid with said plunger and projecting at the forward side of said head, a mounting plate on the forward side of said head at o'needge of said lock plate, said mounting plate having a notch opening through its forward side and its inner edge, a cam, means pivotally' mounting said cam for movements between a position substantially wholly within said notch and out of the way of said lock plate and alocking position projecting through the edge of said notch and into the path of movement of said lock plate, a carrier plate movahly vertically in a plane forwardly-of said lock plate, a pair of vertically-spaced parallel arms pivoted at their res'pe'ctive ends to said mounting plate and carrierplate, a vertical feeler rod, means securing said feeler rod' to said carrier plate for vertica-l'adjustment relative thereto, a feeler means on the lower end of said feeler rod, an extension-like partrigidwith i the upper of said arms and having a slot therein including substantially right angularly related portions, a-piri 'ri'gid with said cam in spaced relatibn to the pivotal mounting of the cam and extending through the open side of said notch and throug-h'said slot, said parts related whereby when saidupper arm is in its upper position-said pin is in the first portion of said slot and said cam is projecting through the edge-of said notch into the path of downward movement of said locking plate to positively limit downward movement of said-plunger and whereby when said upper arm is in its lowest position said'feeler means is in its lowest position and said extension-like part is positioned with said pin in the second portion of said slotand said cam is substantially wholly withinsaid notch and clear of the path of downward movement of said locking plate, cooperating means between said plunger and one of said arms for raising said arms and carrier plate by swinging the arms on their pivotedconnections with the mounting plate as said plunger is moved upwardly in said head, said means adapted to release said parts as said plunger moves downwardly in-said head, and said parts adapted on release to gravitate downwardly whereby on said feeler .means engaging an obstruction further downward gravitational movement of said parts 12 is pie've-ntexlandsaid cam remains' in the first mentioned position and said plunger is locked against all but limited downward movement in said'head.

'7. In a machine, a stationary head and a plunger mounted on said head forverticalreciprocating movement-a lock plate rigid with said plunger, a mountingv plate on said head, a cam, means pivotallymounting said cam on said mounting plate for movements between a position projecting into'the path of downward :movement of said lockplate" and a position clear of such path of movement, a 'c'arrierplate movable vertically in asingle plane, a pair of vertically spaced parallel arms pivoted at their respective ends to said mounting plate and carrierplate, a vertical f'eeler, means securing said feeler to said carrierplate for vertical reciprocating movement therewith, an extension-like part rigid with one of said arms and having a slot therein includingzsubstantially right angularlyrel'ated'portions, a, pin rigid with said cam in spaced relation to the pivotal mounting of the cam and extending through said slot, said parts related whereby. when said one arm-is in" its upper position said pin is in the firstflporti'o'n of saidslot and said cam isprojecting-into the path of downward movementofssaid locking plate to positively limitdownward movement of said plunger and whereby when said one ar-mis in its lowest position said reeler is in its lowestpositionhmd'asaid extension-like part is positioned'iwith saidpin in-the second portion of said slot andsaid oa'm is clear or the path of downwardnmovement of said look- .ing plate, means whereby on its upward movementsaid plunger movesisaid arms; carrier plate and feeler means upwardly swinging said arms on their pivotal connections withthe mounting plate and whereby ondownward movement of the plunger said arms, carrier plate and feele'riar'e released to gravitate downwardly :as :sai d arms swing in the opposite direction, andsaidfeeler adapted on engagement with aIlFObQiEdt during downward movement *of said reeler to said, carrier ,plate and armszagainst rfurtherzmovement in a direction to have the extensiion-like part of said onearm move toareceive'the pin in the second portionof said slot:

GEORGE Number I Date .inoaioc July 28-, 1914 2,049,990 Armstrong;- .Aug. 4; 1936.

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