US1966447A - Safety guard - Google Patents

Description

y 1934- J. c. JYUNKIN 1,966,447

SAFETY GUARD Filed May 23, 1932 5 Sheets-Sheet l J. c. JUNKIN 1,966,447

SAFETY GUARD July 17, 1934.

5 Sheets-Sheet 2 Filed May 23. 1932 J. c. JUNKIN July 17, 1934.

SAFETY GUARD Filed May 23, 1932 5 Sheets-Sheet 3 July 17, 1934.

I J. c. JUNKIN SAFETY GUARD Filed May 23, 1932 5 Sheets-Sheet 4 July 17, 1934. J c, JUNKIN I 1,966,447

SAFETY GUARD Filed May 25, 1952 5 Sheets-Shet 5 IN) C/ZJ/Z aMZZ/ZIZ IZ Patented July 17, 1934 PATENT OFFICE 1 ,966,447 SAFETY GUARD John C. Junkin, Louisville, Ky., assignor of one fourth to Walter R. Wuestand one-fourth to John H. Wuest, both of Louisville, Ky. i

Application May 23, 1932, Serial No; 613,056

28 Claims. (Cl. 192'134) i guards intended to prevent injury to or amputation of the fingers or hand of the attendantof the machine due'to carelessness of said attendant in failing to have his or her hand in a safe position during the approaching movement of the plunger or other part of the machine which presents thesource of danger. I am also aware 10 that it has been suggested that such guards be arranged to move to guarding-position slightly in advance of the plunger, ram or other dangerous element and to so correlate the guard with the operating mechanism of the plunger, ramor the like as to prevent the operating stroke of the latter until the guard has reached its fully guarding position: the theory being that there can be no danger. of injury provided the operating stroke of the plunger, or corresponding part of the machine to which the guard is applied, is prevented when movement ofqthe guard to its guarding position is obstructed, as, for example,

by the hand of the attendant, in removing work from the machine or in placing work into the machine or in adjusting the dies or other parts after the treadle or other operating lever has been operated to set the press in motion.

The prior proposals, however, have not been adequate to remove all. danger, for several reasons, among which are the tendency of many operatives to ride the treadle and the unwillingness of operatives who are paid upon a piecework basis to suffer the loss which follows a slowing up of his or her output. The serious accidents which occur as the result of the tendency of many operatives to ride the treadle are probably equal in number to the aggregate ofthose which arise from every other cause in the operation of presses, etc. and the fact that there is such a tendency and that it is dangerous places upon the operatives of these machines a nervous strain which afiects their efficiency. Moreover, their efficiency .is further retarded since in the operation of the prior safety guards the return i5 of the guard is so timed with the return of the stroke of the plunger or the like that the operative is prevented from removing the finished work and replacing it with a part to be operated'upon except during the pauses between the completion of the return stroke and the beginning of the opc-ratingstroke of the plunger; ram, or corresponding part of the machine; Hence, it is a common practice for operatives of these ma-C chines provided with safety guards to render s'aid guards inoperative and thereby discard whatever safety factor it "may possess, and to rely upon their own dexterity in guarding against accidents, rather than suffer the loss of revenue which they experience when the guardsare in operative relationship with the press.- Indeed, a substantialnumber-of the accidents which now occur result from the use of machines which had been provided with safety guards which wereput out of commission by experienced operatives who objected to their use because of the lessened earnings resulted from their use or because they were not regarded as being effective. Another objection, which particularly applies to many types of these safetyguards, is due to the fact that the means connecting theoperating lever withthe guard is such that pressure imposed upon said lever, whether the latter be of pedal or manual nature, is transmitted to the guard and hence when movement of the guard is obstructed by the, hand of the operative of themachine the pressure imposed on said guard in many cases has resulted in crushing the hand or fingers of said operative.

It is'one of the main purposes of this invention to provide a safety guard which will not besubject to any of the foregoing objections-that is to say,- will not retard the productive capacity of the machine or of the operative of the machine, and hence will offer no excuse for its elimination by the operative of the machine, and whichwill be entirely free from any liability of any injury to the hand-or fingers of the operative arising from any pressure imposed on said hand or fingers by the guard when descent of the latter is obstructed by said hand or fingers and, furthermore,will positively prevent pressure upon the pedal or other operating lever from causing or permitting the working stroke of the plunger or corresponding element of the machine to be initiated until the guard has reached its final guarding position.-

In accordance with the aforesaid purpose I have provided a safety guard mechanism which is characterized in the following several material respects, namely: (1). the movement of 100 the guard proper to its guarding position occurs at the instant the pedal or other operating lever is moved and is of a gravity nature; (2) the return movement of the guard to its non-guarding position commences at the moment the plunger of the press has reached a position'at which its further downward movement will not be attendedwith :any danger to the operative and will be at a'speed which is less rapid atthe beginning of said'rfeturn movement than further along in its progress; (3) the pedal or other operating lever whose initial movement released the guard and permitted the latter to fall into guarding position, is instantly locked against further movement and is held in locked position until the guard has reached its final guarding position; and (4) no movement of the plunger or corresponding element of the machine can take place while the pedal or other operating lever is locked and no movement of said pedal or other operating lever beyond that which causes the guard to be released can take place until said guard has reached its final guarding position.

In other words, one of the important purposes of the invention is to provide a correlation of pedal, or other operating lever, guard and plunger, or corresponding element of the press or other machine to which the guard is applied, by which pressure applied to the pedal or other operating lever, (a) releases the guard and permits the latter to fall, by gravity, (b) at the moment said guard begins to fall the pedal or other operating lever is locked against movement until the guard has reached its final guarding position so that if the guard meets with an obstruction to its downward progress, the pedal or other operating lever remains in locked position and any pressure imposed thereon is not transmitted to the guard or to any part of the press or other machine whose operation by the pedal would permit movement of the plunger or corresponding part; (c) when, and only when, the guard has reached its final guarding position the pedal or other operating element is released and by its downward movement becomes operative upon the clutchtrip dog of the press, or corresponding part of the machine, to release the mechanism which transmits reciprocatory movement to the plunger, ram, or corresponding member of said press or machine; (d) movement of the guard toward its non-guarding position commences immediately before the working stroke of the plunger, ram, or corresponding part is completed, to thereby give free access to the die and work operated on during the return stroke of the plunger or corresponding element of the press or other machine, but this return movement of the guard does not commence until the plunger, ram or corresponding part has reached a position at which the interposition of the guard between the same and the hand of the operator is no longer required; and (e) the pedal or other operating lever will be returned to its non-operating position and in its return movement will cause or permit the plunger or ram or corresponding part to be locked at the end of its non-working stroke until again released by repetition of the foregoing phases of movement.

A further purpose of the invention is to provide a means by which the locking and releasing of the pedal or other operating lever is under control of the guard and is of such nature that it will operate unfailingly in the accomplishment of its purpose and will be so responsive to the movements of the pedal and guard that there will be no perceptible pause in the movement of the pedal or other operating lever in the event that there is no obstruction in the path of the guard which prevents its movement to its final guarding position.

A still further purpose of the invention is to provide means by which upward movement of the guard will start immediately before or at about the same movement the plunger, ram or'correspending part reaches its lowermost position and the first part of its said upward movement will be slow as compared with its speed further along in its travel.

Other purposes of the invention, and advantages which flow therefrom, will be apparent to those persons familiar with safety guard mechanisms now in use and with the mechanisms constituting the subject of the instant application for patent.

In the accompanying drawings I have illustrated the preferred embodiment of my safety guard mechanism as applied to a punch press and will hereinafter describe it in the said relationship, but it will be apparent that its utility is not confined to punch presses and, on the contrary, that it is applicable in principle to any type or kind of operator-controlled machines, such as power punches, shears, embossing hammers, job printing presses, etc. which include a ram, a plunger, a shear blade or other moving part (hereinafter referred to as work performing member) of a nature which would injure or amputate the hand or fingers of an operative in the path of its movement.

In said drawings, wherein like characters of reference denote corresponding parts in the several view:

Fig. 1 is a side elevation of a punch press having the safety guard of the present invention applied thereto;

Fig. 2 is a detail perspective View of an actuating member through which return movement of the guard, proper, from its guarding position, is controlled;

Fig. 3 is a detail representation of the locking mechanism with the face plate of the casing re moved, and shows the members of the locking mechanism in the positions they occupy when the pedal is in its raised position, this View also showing parts of the connecting rods, links, or levers connected to members of the locking mechanism;

Fig. 4 is a view similar to Fig. 3, but shows the relative positions of the members of the looking mechanism when the member thereof connected with the guard has been freed, and is ready to fall with said guard and the pedal has been locked against further downward movement;

Fig. 5 is a View of the locking mechanism with the face plate of its casing and the connecting rods, links or levers omitted, and shows the members of said locking mechanism in the positions they occupy immediately before the guard has reached its final guarding position and the pedal has been unlocked;

Fig. 6 is a view similar to Fig. 5, but shows in full lines the relative positions of the members of the locking mechanism when the guard has reached a guarding position and the member K has been unlatched, and shows in dotted outline the position of said members when the guard is in fully lowered position and member 1 is in the position at which the operative stroke of the ram or other work; performing member of the machine is commenced;

Fig. 7 is a vie-w of the backing member showing the inside of the casing of the locking mechanism, and a plate to which the locking mechanism is secured and by which said mechanism is fastened to the press or other machine;

8 is a view of the face member showing the inside of the casing of the locking mechanism;

Fig. 9 is. a transverse sectional view on the line 9-9 of Fig. 3, but shows the face plate of the casing in dot-and-d-ash outline;

Fig. 10 is a transverse section on the line 10-10 of Fig. 3, this section cutting the backing member, fully illustrated in Fig. '7, on the line 10-10 of the latter figure;

Fig. 11 is a vertical section on the line 11-11 of Fig. 3, this section cutting the backing memher on the line 1l11 of Fig. '7. i

12 is'a cross sectional view on line 1212 of Fig. 3 particularly intended to show the dif' ferent planes which the members which have slidable movement longitudinally of the casing bear to each other;

Fig. 13 is a perspective view of the latch forming part of the locking mechanism;

Fig. 14 is a side elevation of the locking mechanism and certain of the parts which are connected to members thereof;

Fig. 15 is a perspective view of the guard proper;

Fig. 16 is a detail view showing the crank shaft upon which the head or bearing member ofthe ram or plunger is mounted, in section, and also showing the arm which is mounted upon said head or bearing member and from Whose movement the return of the guard to its non-guarding position is controlled, and indicates in dot-anddash outline the throw of said crank shaft and the throw of said arm; and

' Fig. 1'? is a detail View of a connector of universal nature which is preferably employed at several places for connecting members of the operating connections to each other and to members of the locking connections.

The illustrated punch press is of usual construction including a ram A whose upper end is connected by a bearing member, head or pitman B with the eccentric or crank portion C of a crank shaft having members (one of which is shown in Fig. 1 6 and is marked C) which extend laterally in opposite directions from said eccentric or crank portion C and are journalled in suitable bearings in the frame of the press. The shaft referred to commonly derives motion from a power mechanism which is operatively connected to and released from said shaft through the medium of an appropriate clutch, indicated at -D. As here illustrated. the power mechanism includes a belt-driven pulley E. The clutch employed may be of any nature suitable for the particular machine to which the instant invention is applied and need not be illustrated or described in detail, since its details are not a part of my invention. In these machines, the clutch is commonly under control of the operating pedal F of the press, means (as a dog or pawl D being included in the connection between the pedal ment from the pulley E to the crank shaft through said clutch. The press, as well as the clutchand its said meansare of ordinary and well understood construction and therefore it is believed to be unnecessary .to describe the parts, in detail, except to call attention to the fact that these clutches are commonly provided, respectively, withspring press releasecams (D which act to withdraw the dogs or pawls D from their operative' engagement with the clutch jaws when actuated by the pedals.

G designates the guard, proper. This guard, which is shown in Figsl and 15, has a substantiallyhorizontal-U shape, being composed of side arms 9 whose forward ends are connected with each other by a cross arm g Each side arm is to the corresponding end of a pivot shaft G. This shaft G" preferably extends transversely from one side arm to the other and is suitably journalled in the frame of the press. As here shown, each plate G is bolted to the corresponding side arm 9' at a plurality of places and each arm and plate are provided with a series of openings 9' through whi h fastening bolts, indicated at 9', may extend: thus providing for an adjustable setting of the front member of the guard proper and the pivot shaft G in accord with the space occupied by the die H mounted on the bed H of the press.

The front cross; arm g of the guard is preferably provided with an upwardly extending grid g to prevent the operative from having access to the dies or the work on said dies-or, in other Words, to prevent the operative from reaching over the arm y when the latter is in its lowered position-to remove or replace the work or to adjust the dies, at a dangerous moment; and said cross arm gr is also preferably provided with a pad 9 which cushions the shock at the end of the downward movement of the guard.

The bearing member, head or pitman B, here-inbefore referred to, derives reciprocatory movement from the rotative movement of the member C of the crank shaft to which it is suitably secured, and fixed to the upper end of said mem her is an arm I. This arm preferably extends from a base member I having openings through which extend elements for securing it to the bearing member. It will be understood that in the operation of the press or other machine, the rotative and. reciprocative movements of the bearing member coact to cause the arm I to traverse a path which is substantially oval in out line, as illustrated in Fig. 16. It may be here mentioned that the intermediate bend i in the arm is not essential except when required to enable the arm to clear some part of the machine which otherwise Would obstruct its movement.

J designates the face member and J the back member of the casing of a locking mechanism including members (marked K, L and M, respectively) which have longitudinal guided relative sliding movement in and project at their ends from,-said casing. These members K, L and M are interposed in the connections between the pedal F and the clutch trip dog or pawllnot shown) and between the arm I and the guard G and have a co-acting relationship therewith and with each other by which the phases of movei merits of the guard, pedal and Work. performing member hereinbefore referred to are effected. The inner surfaces of the face and back casing members J, J, are relatively formed to receive said members L and M, and also to receive and guide a latch N which has movement transversely of the casing and relatively to the members K, L and M, and further to receive a backing and guiding memberN which engages the outer longitudinal edge of the member M and is arranged in line with the latch N and has movementtransversely of the casing.

One end of the longitudinally slidable lockmember K is pivotally connected to the, corresponding end of, a rod 0 whose opposite end is L'UL nection between the clutch controlling means and the pedal F. The connection between the rod 0 and the lock-member K includes a connector through which said rod extends and in which it is fastened. The preferred connector is shown in Fig. 17 and comprises a hollow body portion P provided with a pivot p which extends loosely through the slot is in member K. Botatably mounted in said body portion P of the connector is a member P having a diametrical opening p through which the rod 0 extends and in which it is held by a bolt 10 having screw threaded engagement with member P. The body portion P is provided with diametrically opposed openings p which are of greater diameter than and register with the opening p and through which the rod 0 also extends. Through the medium of this connector the lower end of the rod 0 is adjustably and pivotally connected to the member K and by the provision of member P rotatably mounted in body member P, openings 1: and p are permitted relative movement whereby the rod may be quickly and accurately positioned without putting strain on pivot p. Moreover, provision for lost motion is made between said rod 0 and member, by extending the pivot p of the connector through a relatively elongated slot k; in the member K, as shown in Figs. 5 and 6. This lost motion is provided for a purpose which will hereinafter be explained. The opposite, or lower, end of the member K is connected with the pedal F by a rod Q whose upper and lower ends extend through and are secured in connectors Q and Q respectively pivoted to the member K and pedal. F. These connectors are preferably of the same construction as that described in relation to connector P.

The upper end of the member L is connected by a link R with one end of a lever B which lever is pivoted at r and is connected by a rod S with the arm I. The connection of the rod S with the lever R is an adjustable and pivotal one, through the medium of a connector at the place S, Fig. .l, which connector in practice is preferably of the same construction as the connector shown in Fig. 17.

The member M is connected with the guard C- by a rod T whose upper and lower portions respectively extend through and are adjustably mounted in connectors at the places marked T and T, Fig. 1. Each of these connectors is preferably of the construction shown in Fig. 17. The connector at T is pivoted to the plate G at this side of the press and the connector at T is pivoted to the upper end of the member M.

The inner longitudinal side of the member M is provided near its upper end with a recess 1 and immediately below said recess 1 with a deeper recess 2. These recesses are defined by a beveled shoulder 3 at the upper end of the recess l and a square shoulder 3 at the lower end of the recess 2. The lower end of the inner lon gitudinal side of said member M is formed with an elongated recess whose upper end terminates in a square shoulder 4 which is spaced from the shoulder 13*. The surfaces 5 and 6 of said side of the member M, above the recess 1 and between the shoulders 3 and i, respectively, are vertical alinement with each other and the inner wall 7 of the recess 1 is vertically alined with the inner wall 8 of the recess which from the shoulder 4 to the lower end of the member M: while the wall 9 of the recess 2 is, of course, in a position which is rearward of the line of the walls 7 and 8. The outer wall 10 of the member M is plain throughout except for an indentation 11, which is formed at a place opposite the shoulder 3. This member M is also provided, near its upper end, with stops 12 which extend laterally in opposite directions from its front and rear sides and near its lower end with similar stops 12, torestrict longitudinal movement of said member to within defined limits.

The member L is formed near its upper end with a perforation. 13 (Fig. 5) to receive the pivot 14 by which the lower end of the rod R is connected to said member. The lower end of this member L is provided with an element L which is mounted on the face of said member and projects laterally beyond the opposite sides thereof. This element is suitably fixed to the lower end of the member L and, in practice, may be integral therewith. Thus it will be noticed that the member L in substance consists of a long stem one of whose ends is provided with a flange which is secured to the front surface thereof and which extends laterally beyond the opposite sides of the stem.

The member K has in one of its longitudinal side surfaces, marked 15, a depression 16 so formed as to provide a plane shoulder 17 at the upper end of the depression, an inwardly beveled wall 18 extending from the shoulder 1'7 to the inner wall 19 of the depression, and a plane shoulder 2-0 at the lower end of said depression. The opposite longitudinal side surface, marked 21, of said member is formed with a depression 22 whose upper end is defined by a shoulder 23. This depression extends from the shoulder 23 to the lower end of the member K. The upper end of the member K is provided, as hereinbefore stated, with a slot 7c to receive the pivot pin 19 of the connector P, this slot being of such length in. relation to the pivot pin as to provide for a lost motion connection between said connector and the member K. This member K is also provided with a guiding projection 49 which extends rearwardly therefrom and with stop projections 4-9 which respectively extend forwardly and rearwardly from the member. The lower end of the member K is formed with a perforation 24 to receive the pivot pin by which the connector Q is connected to said member.

The latch N has its inner surface formed with a depression 25 having at one end a plane shoulder 26, which extends entirely across the latch, and at its opposite end a plane shoulder 27, which extends part-way across the latch, and a beveled shoulder 28, which extends from the plane shoulder 27 throughout the remaining part of the width of the latch. This latch is under tension of a spring 29, one end of which is preferably seated in an opening 30 in the corresponding end of the latch.

The backing and guiding member N is provided with a projection 31 which extends from the outer side of its body and with a roller 32 which is mounted in a recess formed in the body and underneath said projection. This member also is under tension of a spring 33 which is preferably seated in an opening 34 formed in the end of the body opposite the end from which the projection 31 extends.

Referring to the casing, it may be stated in a general way that it is approximately T-shape tively, and also to provide spaceswhich extend longitudinally of the casing from one end to the other thereof, for the reception and operation of 1 the slidable members K, L and M in their proper positions with relation to each other and to the latch N and backing and guiding member N.

As shown in Fig. 7, the illustrated back member J is formed to provide two longitudinal side members and 41 from the upper ends of which lateral extensions 40 and 41 project outwardly, and also to provide two projections 40 and 41 which respectively extend parallel with and are spaced from and are of the same length as, the lateral extensions 40 and 41. The projections 40' and 41 extend from a surface 42 and the projections 41 and 40 extend from a surface 42. These surfaces 42 and 42 extend inwardly, that is, toward the longitudinal central line of the casing beyond the inner ends of said-projections and each has, substantially, the shape of a horizontally disposed T whose stem is between the corresponding projections. Theyare'in the same vertical plane and their inner ends are spaced from each other to form a channel 43 between their heads. t will be noticed that shoulders 44 and 45 are formed by the inner ends of the lateral extensions 40, 40", 41 and 41". 46 designates a surface of the back member whose upper transverse end joins the lower end of the head portion of the T-shaped surface 42 and whose outer longitudinal side joins the inner longitudinal side of the side member 40. This surface 46 is considerably depressed with relation to the surface of the member 40 and preferably is slightly depressed with relation to the surface 42. At its lower endit joinsaa surface 47 which is in the same vertical plane as the surface 42. It is formed with alongitudinal slot 48 whose upper end terminates in a reduced portion 48, This slot is to receive a spring 48* whose function is to counterbalance the pedal so that there is no weight of the pedal transmitted to the rod 0 until after the unlocking of the guard, and also to receive a guide pin 49 which projects from themember K, which member rests against the head .of the surface 42 with its inner edge or side in contact with the shoulders 44 and also against the surface 47 with its inner edge or side against a shoulder 4'7 formed at the junction of the surface 47with the side member 40. The shoulders 44 and 47 are-in al-inement with each other and it will be noticed'that they are, arranged inward of the inner longitudinal side of the 5 member 40 and hence if the surfaces 42 and 4'7 be arranged, as preferred, slightly forward of theforward surface 46, it willbe apparent that friction between the member K and the back member J will be reduced to a minimum. 50 designates a surface which is in the same vertical plane as the surfaces 42,42 and 47 and is spaced from said surface 47 to provide a channel 53 at the lower end of the back member and in line with the channel 43. These channels are tov receive the member L, whose opposite longitudinal sides will be in contact with the shoulders 43 formed by the channel43 andwith the shoulders 53 formed by the channel 53. 54 designates a surface which extends from the inner longitudinal edge of the side member41 to the inner edge of the surface 46 and'from the lower end of the surface 42' to the upper endof the surface 50. This surface54 is in a plane considerably. rearward of the surfaces 42, 42 v46, 47 and ,50 and preferably slightly rearward of the surfaces forming the backsof the channels 43 and 53.

When the several moving members of the locking mechanism are in their assembled relationship upon the back J, the member K rests against the surfaces 42 and 47, with one of its longitudinal edges in sliding contact with the shoulders 44 and 47; the member M restsupon the surfaces 42 and 50 with one of its surfaces in sliding contact with the shoulders 45 and with ashoulder 50 at the junction of the surface 50 and side member 41; and the member L rests against the surfaces 43 and 53 with its opposite longitudinalsides or edges in sliding contact with the shoulders 43 and 53 and also, preferably,

in sliding contact with the corresponding sides of the members K and M. It will be understood thatthe portions of the surfaces 42 and 42 upon which the members K and M rest are those portions which constitute the heads of the T -shaped surfaces and it will also be seen that the upper surface of the member L is in a plane rearward of the upper surfaces of the members K and M. The latch N is mounted upon the surface 42 with its rear end portion in the space or channel formed between the projections 40 and 40" and with its opposite end portion resting upon the surface of the member L; and the backing and guiding member N is mounted upon the'surface 42' in the channel formed between the projections 41 and 41 and with its inner end portion 31 projecting over and in contact with the forward surface of the member M and its roller 32 in contact with the outer longitudinal edge or side of said member M. It will be understood that the latch and backing and guiding member have movement transversely of the easing end are guided in their said movements by the longitudinal walls at opposite sides of their respective channels.

The inner surface of the face member J is in a common plane throughout, except that its upper, widened, portion is provided with a channel and it has lugs 61 and 62 arranged in line with each other on opposite sides of said channel. When this face member is assembled with the back member, its lugfil will lie over, but will not protrude into, the upper end of the channel 43 and its lug 62 similarly will lie over, with out protruding into, the lower end portion of said channel 43 and also partially over, without touching, the upper end portion of the surface 54. The inner surface of this member will rest upon the surfaces 40, 40", 41, 41", 41 and 40 of the back member J; and these two members J .and J" are detachably secured to each other by stove-bolts or other appropriate fastening elements which extend through perforations 63 and 64 in the back member and face member, respectively. Studs 65 project from one of said membersthe back member J in the illustrated embodiment-into perforations 66 in the other of said members, for convenience in setting the two members into their proper relationship with each other in the operation of connecting them'to each other. The outer ends of the transverse channel formed inthe widened part of the casing are closed by any appropriate means, here shown as plates 67 and 6'7 which are secured to the back member and project sufficiently therefrom to cover the outer ends of the channel 60 in the face member.

This locking mechanism is secured to a plate 68 by bolts an d nuts, indicated at 69, or other appropriate fastening means, and said plate in turn is secured to the press or other machine to which the locking mechanism is applied and serves as a means for connecting the locking mechanism to said machine.

The initial position of the several moving members of the locking mechanism is shown in Fig. 3, particular attention being called to the fact that the free end of the latch N is projected into the upper end of the recess 2 of member M with its upper surface against the shoulder 3 When the parts are in this position the beveled portion 28 of the latch (Fig. 13), is in contact with the beveled portion 18 of the member K and the upper surface of said latch adjacent said beveled surface 28 is spaced from the shoulder 17 of said member. The members K, L and M, and also the pedal and connecting rods are in their raised positions and the pivot 19' of the holder or connector P is in the lower end of the slot is in the member K and the indentation ll of the member M is arranged above and spaced from the roller 32 of the backing and guiding member N.

In the operation of the mechanism: the outer end of the pedal F is depressed and in its initial downward movement lowers the member K to the limit of the slot is, at which time the shoulder 17 of said member will rest upon the upper surface of the latch N, as shown in Fig. 4. During this movement the beveled surface 18 of member K slides upon the beveled surface 28 of the latch and thereby retracts the latch from the recess 2 in the member M without completely disengaging the shoulder 1'7 from the latch. This position of the parts is shown in Fig. 4, and it will be noticed that the end of the latch has been completely disengaged from shoulder 23 of the member M and is substantially in line with wall 7 of recess 1. Member M, accordingly, is free, to fall and since it is connected with the guard G, said guard and member M fall together, by gravity, while member K is locked against further downward movement by contact of its shoulder 17 with the upper surface of the latch. It will be understood that in the movement thus far described no force is imposed on rod 0, due to the 10st motion connection between member K and said rod. If the downward movement of the guard to its final guarding position is unobstructed, the beveled shoulder 3 of the member M immediately before the last part of said movement, at the position shown in Fig. 5, will come into contact with the end of the latch and by its further downward movement will force said latch further to the right sufficiently to disengage the upper surface of the latch from the shoulder 17. The last named position of the parts is shown in Fig. 6. If, on the other hand, downward movement of the guard is obstructed, by the hand of the operator or by any other object, contact of shoulder 3 with the latch is prevented and hence member K remains in its locked condition and is incapable of operating the rod 0 even though pressure be applied to the pedal. In short, member K is freed from the latch only when the movement of the guard is unobstructed and said guard has reached its final guarding position and no movement is transmitted from said member to the latch-dog releasing rod 0 until said member K has been unlatched. Fig. 5 shows the relative positions of the parts at the moment member M has dropped sufliciently for its beveled shoulder to make contact with the end of latch N and before it starts to force said latch into position to un-lateh member K, and it will be noticed that the roller 3-2 of the guiding and backing member is a position in which slight further downward movement of the member M will cause said roller to enter the indentation 11.

When the member K has been unlatched the pedal F is free to continue its downward movement and this movement of course is transmitted to the member K and through said member K to the rod 0 which, being now operated, causes the clutch to become operative to transmit power from the power mechanism and, in short, to rotate the crank shaft and hence impart reciprocatory movement to the work performing member A. As hereinbefore stated the head or bearing member B carries an arm I which is connected by a rod S with a lever R whose end is connected by a link R with the member L of the locking mechanism. As shown in the drawings, the shoulder 4 of the member M and the shoulder 23 of the member K are normally spaced from the upper edge of the element L fixed to the flower portion of the member L and are in such position with relation to the laterally projecting ends of said element L as to be engageable by the latter in its upward movement. When the member M has dropped to its lowest position, as shown in Fig. 6, its shoulder 4 will be in such relationship to the upper surface of the corresponding protruding end of element L as to be engaged thereby immediately after the member L commences its upward movement. This upward movement of the member L is derived from the arm I through the connections hereinbefore referred to, during the downward stroke of the work performing member A, and the parts are so correlated that before said downward stroke has been completed, but not until the member A has reached a safe position with respect to the operative, the shoulder 4 will be engaged by the corresponding protruding end of element L; and hence upward movement of the element M and of the guard to its non-guarding position will commence near the end of the working stroke of the work performing member A. Continued upward movement of the member L beyond the point at which its element L has engaged the shoulder 4 of member M brings said element into engagement with the shoulder 23 of member K and raises the latter member the comparatively short distance which is required to return it to its initial position in relation to the latch N, which latch is then forced by its spring 29 into a holding relationship with the member M and with the member K. This movement of the member K to its initial position returns the pedal to its raised position, and accordingly, the pedal and the aforesaid members of the locking mechanism become thus set for repetition of the foregoing operations.

In the downward movement, and also in the upward movement, of the member M its side or edge 10 is in contact with the rear surface of the projection 31 of said member l and said member N thereby assists in overcoming any wobbling tendency of the member M, the roller 32 further acting to reduce friction. When the member M has reached its lowermost position, said roller 32 will have entered the indentation l1 and will act as a stop, preventing rebound of the guard G.

From the foregoing it will be seen that initial movement of the pedal, or other operating lever employed in lieu of the pedal, within the range of the lost motion connection of the member K with the rod 0 will act upon the-latch N to retract the latch from the member M without-disengaging said latch from the member K, whereupon the member M will drop and the guard G will fall the locking mechanism occur in such rapid sue-1 cession that no'perceptible pause is experienced in the operation of the operating lever unless an obstruction is interposed to the movement of the guard to its final guarding position;

It will also be noticed that the return of the guard to its non-guarding position is effected by power derived from the crank shaft of the machine and transmitted to themember L through the rod S, rock arm' R and link R by which the return motion of the guard to its non-guarding position is 180 ahead of the returnmotion of the work performing element of the machine. In the movement referred to the arm I by which the upper end of the rod 0 is operated causes the upper end of said rod to move-in' a substantially elliptical path, as hereinbefore described.

Having thus described the invention what I believe to be new and thereforeclaimas my 1nvention, is:-

l. A safety guard mechanism for a power operated machine having a movable work performing member, driving means and control means, including, an actuating element for effecting-intermittent operation of said work performing member by said driving means: said safety guard mechanism comprising a guard, a first member, having connection with the guard, a second member to be connected to the actuating element of the machine and means operable upon initial movement of the second member to'relea'se the first member and guard and simultaneously therewith lock the second member against further movement until the guard has reached, substantially, its guarding position.

2. A safety guard mechanism according to claim 1 in which said means is also operable to cause the second member to be automatically released under control of the guard when said guard has reached a guarding position.

3. A safety guard according to claim 1 in which the guard whenreleased falls by gravity toward its guarding position.

4-. A safety guard mechanism according to claim 1 in which the guard when released falls by gravity toward its guarding position and comprises a lightly constructed frame having'side arms adapted for pivotal connection with the machine and a front arm provided with a cushioning member.

5. A safety guard mechanism for a power operated machine having an actuating element for controlling the operation of the machine: said safety guard mechanism comprising a guard and a locking means which includes a first, a second and a third member, each movable relatively to the others, said first member being movable with the guard, said second member being adapted to be connected with the actuating element of the machine and when so connected to be moved thereby, and said third member being operatively related to the first and second members and cooperating therewith to cause the guard to be released for movement toward guarding position upon initial movement of the second member with the actuating element and simultaneously therewith eifecta locking relationship between the second and third members and maintain said relationship until the guard has reached a guarding position.

6. In a power operated machine having a movable work performing member, driving means and control means for effecting intermittent operation' of said work performing member by said driving means:- a safety guard mechanism comprising a guard mounted to have movement to and from guarding position with respect to said work performing member, and means operatively related to said control means and guard and including members coacting to release the guard for movement toward guarding position upon initial movement of said control'means, lock said control means against operative movement in'the initial movement of the guard toward guarding position and unlock said control means for operative movement in the further movement of said guard to substantially. guarding position.

7. Ina power operated machine having a work performing member, driving means, and control means accessible to an operative for effecting working and return stroke movements of said. work performing member by said driving means, periodically: a safety guard mechanism comprising a guard movable to and from guarding position with respect to said' working performing member and means operatively related to said control means and guard and including members co-acting-to lock the guard in non-guarding position between the working stroke movements of the work performing member, unlock the guard for movement toward guarding position, lock the control means against operative movement in the initial movement of the guard toward guarding position and unlock said control means for operative movement when the guard reaches substan- 8. In a power operated machine having driving means, a shaft provided with a crank, a pitman carried by said crank, a work performing member connected with said pitman for working and return stroke movements, and control means for effecting periodic rotation of said shaft by said driving means: a safety guard mechanism comprising a guard movable to and from guarding position with respect to said work performing member, means operative to lock said guard in non-guarding position, means to unlock said guard for movement toward guarding position, means operative in the initial movement of said guard toward guarding'position to lock'said control means against operative movement, means operative in the further movement of said guard to substantially guarding position to unlock said control means for operative movement thereof, "and means operative by the crank of said machine for moving said guard toward non-guarding position during the working stroke movement of said work performing member.

A. A power operated machine according to claim 8 in which the means operative by the crank of the machine is connected to the pitman and operates to cause the returnmovement of the guard to be accelerated after an initial movement thereof.

10. A power operated machine according to claim 8 in which the means for returning the guard to non-guarding position includes a lifting member, an arm adapted to be secured to the head of said pitman and having movement in substantially an elliptical path, and connections between said lifting member and arm whereby the return movement of the guard from guarding to non-guarding position is accelerated after its initial movement.

11. A safety guard mechanism for a power operated machine having a movable work performing member, driving means and control means for eifecting intermittent operation of said work performing member: comprising a guard adapted for connection with said machine, looking means having connection with said guard and adapted for lost motion connection with said control means, said locking means including members coacting to lock the guard against movement toward guarding position, release the guard for movement toward guarding position upon movement of said lost motion connection, lock the control means against operative movement in the initial movement of said guard toward guarding position and release said control means for operative movement thereof in the further movement of said guard substantially to guarding position; a lifting member operative to effect the return or the guard to non-guarding position, and means adapted for connection with said driving means for actuating said lifting member.

12. A safety guard mechanism for a power operated machine having a work performing member, driving means and control means accessible to an operative for effecting intermittent operation of the work performing member by the driving means: comprising a guard movable to and from guarding position with respect to the work performing member, a latch, a first member, movable with the guard, and a second movable member, adapted for lost motion connection with the con trol. means, said members and latch provided with surfaces co-acting upon movement of the second movable member within the range of the lost motion connection to move the latch out of latching engagement with the first member and into latching engagement with the second member, and also operative at a predetermined place in the movement of the first member to move the latch out of latching engagement with the second movable member.

13. A safety guard mechanism according to claim 12 in which the co-acting surfaces of the first and second movable members and latch include shoulders for engagement with the latch and bevels for moving the latch into or out of engagement with said shoulders.

14. A safety guard mechanism according to claim 12 in which said members and said latch are movably disposed in guide channels in a housing adapted for connection to said machine.

15. In a safety guard mechanism for a machine having a work performing member, power means for operating the work performing member and a control means including an operating lever and means for connecting the power means to and disconnecting it from, the work performing member when said lever is correspondingly operated: a locking means comprising a first member, adapted for connection with the operating lever, a second member adapted to be connected to the guard and a spring-pressed latch; said members and latch being movable relatively toeach other and including surfaces, co-acting in the initial movement of the first member to cause the second member to be released for movement relatively to the latch and first member and to eiiect a locking engagement between the latch and said first member, and upon movement of the second member to a predetermined position to cause the first member to be released for the remainder of its movement.

16. A safety guard mechanism according to claim 15, in which the locking means also includes a third member, and said third member is adapted for connection with the power means of the machine and is operable to return the first and second members to their initial positions with the second member in locked relationship with the latch.

1'7. A safety guard mechanism according to claim 15 in which a guiding member is yieldably pressed against and has a stop slidably engaged by, the side of the second member at a place opposite the latch.

18. A safety guard mechanism according to claim 15 in which a casing is provided within which said members and latch of the locking means are mounted in a guided relationship and from which the ends of the members protrude.

19. A safety guard mechanism according to claim 15 in which the locking means also includes a third member and said third member is adapted for connection with the power means of the machine and is operable to return the first and second members to their initial positions in locked relationship with each other, and in which also a spring-pressed guiding member is provided and includes a stop slidably engaged by the side of the second member at a place opposite the latch, and in which further, a casing is provided within which all of said members and the latch are mounted in a guided relationship and from the ends of which the first, second and third members protrude.

20. A machine comprising a work performing member having operating and returning movements, power means for operating said member, and means, including an operating lever and a clutch for controlling the operations of the power means, a guard having pivotal connection with the machine and means for moving said guard into and out of guarding position with respect to the work performing element; said means including a first and a second reciprocatory member, a connection between the first member and the operating lever, a lost motion connection between said first member and the clutch, a connection between the second reciprocatory member and the guard, and a latch operatively related to said first and second members; said members and latch having surfaces relatively arranged to cause the latch to be moved to permit the second member and the guard to fall upon initial movement of the operating lever within the limits of said lost motion connection and at the same time the first member to be locked against further movement by the operating lever, said surfaces also relatively arranged to cause the second member to free the latch from the first member in the further movement of the guard to its guarding position.

21. A machine according to claim 20 in which a third reciprocatory member is provided and is operated under control of the power means to move said first and second members to their initial positions.

22. A machine according to claim 20 in which a third reciprocatory member is provided and is operated under control of the power means to move said first and second members to their initial positions and in which the means operated by said power means for so moving the third member comprises connections adapted to move the third member into lifting engagement with the second member during the last part of the working stroke of the Work performing member and to raise the guard into non-guarding position in advance of the non-working stroke of said work performing member.

23. A machine according to claim 20 in which a third reciprocatory member is provided and has connection with the power means, the connection including an arm movable in a substantially elliptical path, a rocker arm, a link connecting the rocker arm with the third member and a rod connecting the rocker arm with the first mentioned arm, said connections co-acting to move the third member into lifting engagement with the second member during the last part of the working stroke of the work performing member and to raise said guard into nonguarding position in advance of the non-working stroke of said work performing member and to cause said movement of the guard to be accelerated after the initial movement thereof.

24. A machine comprising a work performing member having operating and returning movements, power means for operating said member, means for controlling the operations of the power means, a guard movable into guarding and non-guarding positions with respect to the work performing member and means connecting the, guard with the power means, adapted to move the guard from its guarding position to its nonguarding position in advance of the returning movement of said work performing member.

25. A machine according to claim 24 in which the connection between the guard and the power means includes a rod one of whose ends has connection with the power means and is moved in an approximately elliptical path thereby, a rocker arm to which the other end of the rod is connected, a reciprocatory member having connection with the rocker arm and means operated by the reciprocatory member and connected to the guard for moving the latter to its non-guarding position. 7

26. A machine comprising a work performing member having operating and returning movements, power means for operating said member, means for controlling the operations of the power means, a guard movable into guarding and non-guarding positions with respect to the work performing member and operating connections to start movement of the guard from its guarding position to its non-guarding position before the work performing member has fully completed its work performing stroke.

27. A machine according to claim 26 in which the operating connections are arranged to cause that part of the return movement of guard which occurs while the work performing member is completing its working stroke will be at a speed relatively slow with respect to its speed during the return stroke of the work performing member.

28. In a power operated machine, the combination of a movable work performing member, driving means, a clutch having a dog or pawl operative to control intermittent movement of the work performing member, an operating lever, means forming a connection between the operating lever and said dog or pawl, said connection including elements relatively arranged to provide a lost motion permitting initial movement of the operating lever without transmitting corresponding movement to the dog or pawl, a safety guard and an automatically operative locking mechanism under control of the guard, for preventing movement of said connection beyond its referred to initial movement until the guard is in fully guarding position: whereby the work performing element is locked against work performing movement when for any reason the guard is not in its said fully guarding position.

' JOHN C. JUNKIN.

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