US2257273A

US2257273A - Safety device or guard for machines

Info

Publication number: US2257273A
Application number: US268698A
Authority: US
Inventors: Nasmith John Irving
Original assignee: Vickers Armstrongs Ltd
Current assignee: Vinters Armstrongs Ltd
Priority date: 1938-04-21
Filing date: 1939-04-19
Publication date: 1941-09-30
Anticipated expiration: 1958-09-30
Also published as: FR853320A

Description

Sept. 30, 1941. I J. NASMITH 2,257,273

SAFETY DEVICE 0R GUARD FOR MACHINES Filed April 19, 1939 8 Sheets-Sheet l I I l I I I I I I I I I l l l r I INVENTOR JOHN IRVING NASNITH ainWmifizmfihg$ "TOR-KEYS Sept. 30, 1941. J. LNASMITH SAFETY DEVICE OR GUARD FOR MACHINES Filed April 19, 1939 8 Sheets-Sheet 2 ATTORNEYS Sept. 30, 1941. J. I. NASMITH SAFETY DEVICE OR GUARD FOR MACHINES 8 Sheets-Sheet 5 Fild April 19, 1939 LII Ill! lllll... llllllllllll ATTORNEYS Sept. 30, 1941. J. I. NASMITH SAFETY DEVICE 0R GUARD FOR MACHINES Filed April 19, 1939 8 Sheets-Sheet 4 mvsnrom WITH Joan IRVING NR5 Sept. 30, 1941. v NASMITH 2,257,213

SAFETY DEVICE OR GUARD FOR MACHINES Filed April 19, 1959 8 Sheets-Sheet 5 \NVENTOR JOHN \Rvmer unsvz m 6Y1 Arr-owner's Sept. 30, 1941. J. I. NASMITH SAFETY DEVICE OR GUARD FOR MACHINES I Filed April 19, 19:59

8 Sheets-Sheet 6 ww mm n. u H... 3 N .m m Ms v% 3 b h NM u m m NW w m J Se t. 30, 1941. J. 1. NASMITH 2,257,273

'SAFETY DEVICE OR GUARD FOR MACHINES Filed April 19, 1939 8 Sheets-Sheet 7 JOHN \Rvme ms ATTORW Sept. 30, 1941. J. I. NASMITH 2,257,273

SAFETY DEVICE 0R GUARD FOR MACHINES Filed April 19, 1959 8 Sheets-Sheet 8 INVENTOR= JOHN 'IRVING NASMITH ATTORNEYS Patented Sept. 30, 1941 SAFETY DEVICE OR GUARD John Irving Nasmith, Ghislehurst, England, as-

signor to Vickers-Armstrongs Limited, London, England, a British company Application April 19, 1939, Serial In Great Britain April 21, 1938 17 Claims.

This invention relates to safety devices or ards for use in connection with machines of the type wherein the material to be operated upon is fed by an operator into a working space lative space required, the high speed at which any guard must operate and the fact that the operators control must be such that a single or a number of consecutive strokes may be made at will.

Manysafety devices have been proposed and the present invention relates to devices of the type wherein the operators control is interconnected with the'guard system only, the guard itself controlling the operation of the machine by interconnection with the machine clutch, the latter being otherwise quite independent of the operators control. The application of this principle in practice especially where high working speeds are necessary presents mechanical difficulties which up to the present have prevented this type of guard, which in principleis the most satisfactory yet proposed for this type of machine,from coming into practical use.

Guard devices of the type referred to, must, in order. to be of practical value fulfill a number of working conditions and none so far proposed has met all these conditions satisfactorily. The chief of these conditions are that the guard must not reduce visibility, or occupy or reduce the manipulative space or in any way otherwise impede the operator, secondly it must not cause a painful blow to the operators hand even though actual injury is avoided, thirdly it must be safe in its clutch control against wear and although it must be sensitive in order to be safe it must be insensitive in the relation between the guard position and the position of the. means actuating the clutch, and fourthly it should render the machine automatically inoperative by the operators control if the guard has been temporarily removed for any purpose.

"The first condition implies that the travel of the guard must be as great as possible and this together with the high speed at which many machines of thistype have to work precludes the use ofgravity for any part of the guard motion. Further, the rapid motion of the guard system renders it necessary in practice to provide a constructien such that the inertia forces on stoppage of the guard are not transmissible to any obstruction such as the finger except by a very small controlled amount, and not involving the positive instantaneous destruction of the kinetic energy of the whole guard system. To satisfy the third condition for safety enumerated above it is essential that when the guard has made its full unimpeded travel, the means for stopping the clutch from driving must be still capable of full relative engagement, the final release of said means being a subsequent automatic action after the guard has reached the safety position. As the operators control is interconnected with the guard system only it is readily possible to satisfy the fourth condition of safety by means of suit able constructional details provided the other conditions have been satisfied.

In some machines of this type, Where the Working space has to be adjustedto admitvarious thicknesses of work, it is also desirable that the guard should provide protection against the machine being operated when no work is presented as serious injury can be sustained unless the guard is capable of fulfilling this requirement. In the case of certain machines of the type specified fulfilment of this last condition is not of any advantage as no work of appreciably different thicknesses is introduced and therefore the ordinary safety of the guard is never affected by having to increase the working space to take the greater thicknesses. The presence or absence of this further feature in any particular application necessitates only modified detail construction, whilst retaining all the other features essential in every case.

It is the chief object of the present invention to evolve a guard system of the above type which will satisfy all the above practical demands.

According to the invention a control member adapted to be actuated by the operator is operatively connected to a guard device which is in urn adapt d to control the enga ement or disengagement of aclutch controlling the operation of the machine, two members being provided which are adapted to co-operate with each other in such a manner that disenga ement of the clutch will take place on contact of said members overthe whole of their designed engaging surfaces while engagement of said clutch will only take place after disengagement of the members which is effected by virtue of a subsequent. relative movement after the guard has come to rest in a predetermined safe position or range of positions. Preferably a pair of interlocking elements is interposed between the guard and one of the members controlling the clutch, the arrangement being such that actuation of the members to effect engagement or disengagement of said clutch will be dependent upon the relative position of the interlocking elements. The construction is also such that the guard will be moved away from its safe position positively, but will return to such position under the action of resilient means. Further, the guard is also preferably adapted to move initially into its safe position on actuation of an actuating member such as a pedal, but when the pedal is retained in its operative position and the machine runs continuously the arrangement is such that said machine and the guard will be under the control of a positively operated component of the machine mechanism, such as a .cam or other suitable 7 member supplied or used for the purpose. In addition, means are preferably incorporated adapted toprevent starting of the machine if the guard moves beyond its predetermined safe position and further to render the operators control inoperative if the guard is removed'temporarily for H sure block Hi. The essential function of a machine of this kind is to secure a strip of adhesive paper or other material to work presented by the operator on the anvil II, and in order to do this the pressure block 16 must press the strip under considerable pressure on to the work on said anvil and it is necessary therefore to protect the operators fingers from being trapped under said pressure block. The details of the machine apart from the guard do not constitute a part of the invention and hence they will not be furthere referred to herein. The guard proper indicated by I! and shown in detail in Figures 5, 6 and 7 is adapted to shroud as completely as is necessary the pressure block i6. As the front face 1 of the anvil H requires to be set longitudinally for varying depths of work a subsidiary guard I8 is provided which is associated with the main guard l! in such a manner as to be adjustable longitudinally relatively thereto and is adapted to protect the operator against so plac ing his fingers that they will come between the side walls of the main guard H. The subsidiary guard formsno parts of the present invention, however, and will not therefore be further referred to herein. Referring now especially to Figure it will be seen that the guard I1 is mounted on a stem 19 by means of two'members Figure 1 and la are a side elevation of the its attachment shown separated from the mai chine.

Figures 6 and '7 show an end and plan view respectively of the guard proper.

Figure 81s a side elevation of the relevant-parts of a wire stitching machine having-a modified form of guardsystem according to the invention applied thereto. Figure 9 is a part section on the line '9-9-of Figure 8,

Figures 10 to show detail views of parts of the guard system in various relative positions and under various circumstances.

Fig. 16 shows one form of one revolution clutch adapted for application to either the corner staying machine or the wire stitching machine illustrated in the preceding figures. Fig. 17 is a section on the line l'll'| of Fig. 16.

Referring toFigures 1 and 2, l9 denotes the framework of a corner staying machine while M denotes an-anvil or work support which in the case of a machine of this kind requires only longitudinal setting for different depths of work the thickness of the material being operated upon varying only very slightly and from the point of view of the guard of the-machine it may be considered constant; Mounted so as to be slidablevertically within-the framework Hl'is a ram 12 to'which a reciprocatory motion isim- 20 and 2!. The stem I9 is supported in the framework H] and in the embodiment illustrated is housed in a slideway formed in the back-of the ram l2. The guard I! and its attachment are adapted to constitute a freely movable system which is supported by an arm 22 (see also Figure 2) which contacts with the under side of the member 20. Further, the guard is also resiliently connected with the arm 22 by means of a spring A 23 which is anchored at one end to the member 20 by means of the pin 29 and at the other end .to the arm 22 by means of a pin 22.

else'adapted to carry an arm 25 to which the frame 10.

Sliding in the framework Hi is a member 33 parted from'adriving shaft-i3 in-any suitable manner. In the embodiment illustrated for ex ample, said ram is adapted to be actuated by a pin l5 suitably attached to the drivingshaft l3.

Conveniently mounted on the ram 12 is a presoperators control is connected in any suitable mannenfor example, as indicated in the figure,-

carries a pin 21 to which is attached one end of,

a spring 28, the other end of which latteris secured to a pin 29 mounted on the machine (Figures 1, 3 and 4) which constitutes oneof a pair of interlocking members adapted to control the machine clutch and said member is adapted to move in a slideway formed in a bracket3l bolted or otherwise secured to the machine frame. in. Pivoted on a pin 32 mounted on the frame work It! is a member 33 which is adapted to co-operate with the member 39 and to constitute the second interlocking memben said member 33' being normally held in the position shown in Figure l by means of a spring 34. A projection 33 formed integrally with the member 33 is adapted to co-operate with a recess 35f formed in the member 30 in a manner and for the purpose hereinafter more fully described. The member 30 is also provided with connecting pins '35,

36 and 3i, and is retained in its slideway by means of a cover plate 38. Referring now more particularly to Figure 3, it will be seen that the shaft 24 also has secured to it an arm 39 which isjoperatively connected to the member 30 by the pin 36 which engages in a slot in said arm. Pivoted on the framework on a pin 49 is a cam lever 4 l which is pivotally connected to the member .30 by means of the pin 31, whichlatter is adapted to engage a slot in said lever. The lever 4| carries a roller to co-operate with a cam 42 carried by the driving shaft I3, said cam serving positively to, control the lever 4| as and when required, as will be hereinafter described. Pivoted on a pin 43 in the framework IE] is a member 41, which is normally held against a stop pin 48 by means of a spring 49 or any other suitable device. The upper extension of the member 41 is adapted to co-act with a clutch engaging member'5ll, being normally held in engagement therewith as'shown in Figure 3. The member 41 is adapted to be actuated by means of the pin 35 carried by the member 30. Referring now to Figure 1 it will be seen that a double armed lever 52 is provided which is pivoted on a pin one end of said lever being forked, and adapted to co-operate with a. pin 53 in the member 2| of'the supported guard system (Figures 1 and 5) while the other end carries a roller 52' which is adapted on actuation of said lever to cooperate with the secondinterlocking member 33. The clutch itself which is associated with the shaft i3 may comprise any type of one revolution clutch, all of which have a member corresponding to the memberifl.

When the machine is at rest the position of the parts is as shown in Figures 1 to 4, the rod 26 associated with the operators control being held downwardly by any convenient means in such a manner as to counteract the spring 28 operating the guard system. When the operator requires to start the machine the rod 26 is lifted whereupon the spring 28 will impart a rotary movement to the shaft 24 and consequently to the arms 39 and22 associated with said shaft. Movement of the arm 39causes the member 3%) to move to the right having reference to Figure 3 andhence the cam lever 41 will be moved towards the cam 42. Simultaneously the lever 22 is swung downwardly and due to the action of the resilient connection 23 the guard I I is brought down, thus causing tilting of the lever 52. When the guard approachesclosely to the anvil Hthe roller 52' on the end of the lever 52 will contact with the interlocking member 33 and will cause pivotal movement thereof with, the result that the projection 33' ofsaid member will begin to move out of the pathof the slot 38 in the interlocking member 36. Only when the guard I! is right down will the projection 33 be clear of the slot 30 thus allowing the member 30 to pass further to the right. The guard H may be made of transparent material and when down on the work it is adapted completely to protect the space under the pressure block i6. If the guard attains the safe position the member 35 will continue its motion to the right under the. influence of the spring 28 while the arm 22 will also continue to move, the guard remaining stationary on the worklby virtue of the resilient connection 23 between said arm 22 and the guard. At the same timethe pin 35 will, due to the movement of the member at, contact with the. member 4'! which hitherto has remained in full engagement with the/clutch control member 50 and on contact of said pin with the member 41 the latter will be moved aboutits pivot 43,'thus enabling the clutch control member50 to effect engagement of the clutch and then,- and then only, can the machine start. When the ram [2 begins to rise, usually about half a revolution of the shaft [3 takesplace and the arrangement is such that the cam 42 will cause the lever 4| to .moveto the left against the spring 28. In this way the guard is lifted and all the parts are restored to their initial position some little time priorto the completion of one revolution, It will be clear from the above, however, that the member 41 will befully restored in the path of the member 50 shortly after half a revolution ofthe shaft l3 has taken place.v If the operators control rod remains in the set-. tingcn position the machine will run continuously, the guard and its associated mechanism being then controlled entirely by the cam 42 and the spring 23. The cam 42 is of such a form that when the guard has been fully raised some little time prior to the completion of one revolution themember 3!) will have again completed its movement to the right before the one revolution is completed so that the member 4! will be clear of the member 5.9 and will allow engagement of theclutch and continuous running of the machineuntil the operators control is operated to stop said machine, whereupon further movement of the member Mrelatively to the member 50 will be prevented. 1

The above indicates the normal action of the machine and it remains to'be described how the guard protects the operator completely.

It will be clear that owing to the resilient connection 23 between the arm 22 and the guard proper and its attachment, the latter system may be arrested and become stationary at any position in its downward path. It will also be understood from the above that in anyposition other than that wherein the guard is at the safe position, the interlocking member 33 will lie in the path of the interlocking member 30 and prevent movement of the latter member to the right to effect engagement of the clutch. The path of. motion of the member 35 is, as will be appreciated from the drawings, at right angles to the plane of motion of the member 33 and the presence of ber '41 and consequently the members 41- and 5B controlling the clutch will remain in full engagement and as after release by an unimpeded. motionof the member 30 the member 41 is fully restored by the cam 42, it is impossible for these two members to contact with each other again, except when in full engagement. It will be clear, therefore, that no wear and rounding on the edges last in contact on release of the member 50 by 4'5 can afi'ect control of the clutch one of the essential conditions for safety. The complete withdrawal of a member such as 41 after the guarding action is complete is an essential feature of the invention. Referring now to the action of the interlocking members it. will be seen from the above that commencement of withdrawal of the member 33 out of the path of the member 30 can take place only as the guard approaches very closely to the anvil II and up to a distance equivalent to the thickness of a finger tip the member 33 will not have moved." Beyond this point withdrawal takes place and there will be, just before the guard comes to reston the work, a small indeterminate period inwhich the member 30 may or may not pass the member 33. This indeterminate period, however, is. clearly of no consequence from the safety point of view and wear of the connection acts in the direction of greater safety. Further as the two'interlocking members are arranged to move in planes at right angles to each other and also as there can be no relative movement between them after contact they cannot deteriorate by use if. the edges of the interlocking members are initially squared and hardened. Further, when the interlocking members engage as they impinge at right angles the inertia effect of the guard connecting system cannot be transmitted to the guard proper and its attachment and is therefore'not involved in any blow that may be sustained by an obstruction of the guard motion. When the guard proper and its attachment are arrested before completion of their full travel the only forces that can act on the obstruction are that due to the kinetic energy of the guard proper and its attachment, that is the elements [9, 2i], 2|, IT and 52 and to the force exerted by the resilient connection 23. No other forces from the guard mechanism are transmissible to the guard proper. Of the former forces the ki- "netic energy of the guard proper and its atwillbe inadequate and the machine will be re-.

duced to making single strokes on operation of the operators-control. Thus the force sustained by an obstruction can be reduced to a value which can be borne with impunity on the hand or finger- It is necessary for various purposes occasionally to remove the guard l1 and this may be effected by releasing the pin 53 (Figures 1 and 5) ,which is suitably threaded and sliding the member 2| off the member 29 whereupon the guard is removable. It will be clear that on removal'of the guard the connection to the lever 52 will be broken and said lever can no longer be actuated by the guard mechanism. Consequently the interlocking member 33 cannot be actuated and hence the machine cannot bestarted by the operators control until the guard is replaced.

Referring now to the application of the invention to a wire stitching machine as indicated in Figures 8 to the line marked W W in these figures represents the top of the work which remains very approximately a constant relative to the stitching mechanism disposed above but therelation of the latter to the position at which thework support is set varies considerably and according to the variation of thickness of work to be stitched. -In this case, therefore, a variable working; space has to be protected and as an illustration of the perfect generality of application of the principle of guarding according to the invention this application will now be described.

Referring to'Figures 8 and 9 of the drawings, the framework of the machine is indicated by $54; a, driving shaft 55 being mounted therein and carrying a clutch engaging and disengaging member 56 suitably mounted therein. At the shaft 55.

'E! by means of a pin .78 is a spring 19, the other.

opposite end of the driving shaft connection is made to the stitching mechanism housed in the forward part of the framework 54, but since such mechanism forms no part of the present invention it will not be further referred to herein.

In Figures 8 and 1-0 to 15 one suitable form of guard is shown which is divided into ,two lateral parts 51 and 58 but such a construction is not essential, the only condition which has to be satisfied being that the guard should be cut away as required to allow the mechanism inserting the stitch to contact with the work. The guard is mounted on a freely movable stem 59 housed in the framework in any convenient manner, said stem 59 being positively supported by one arm of a lever 69 pivotally mounted about a pin 5i which is carried by a bracket 62 secured to the framework or which may if desired be mounted in said framework. The stem 59 and the lever 60 are also resiliently interconnected by means of a spring 63 which is secured at one end to a pin 64 on the stem 59 and at the other to a pin 65 carried by said lever. In the embodiment illustrated a slot 66 is cut in the guard stem 59 and the presence of this enables the guard stem itself to function as one of the interlocking members,'a separate member for this purpose such as the member 33 in the previous embodiment being thus dispensed with. The other arm of the lever BIJ'is pivotally connected by means of a pin 61 with an interlocking member 68 which is slidable longitudinally and is in turn also connected to the clutch control. The member 68 is adapted to co-operate with the slot 66 in the guard stem 59 in a manner hereinafter more fully described. Also connected to the pin 57 is a link 69 which is connected by means of the pin 19 to a member 7 I, which is adapted to co-operate with the member 56 and is in this case shown as sliding in a bracket 12 secured to the machine framework. A cam lever 13, which is pivoted on the framework at 14, is also adapted to co-operate with the pin it carried by the member H, said lever being provided with an actuating arm carrying a pin 75 and a cam roller I6 adapted to cooperate with a cam 'I'I secured to the driving Also secured to one end of the member end of which is anchored to the pin in the machine framework. The member II also car-.

ries' a further pin 8| adapted to'co-act with one arm of a lever 82 pivoted at 83 in the framework or in the bracket 72 secured thereto. The second arm of the lever 82 has a rod 84 pivotally connected thereto, which latter is adapted to be connected at its other end with the operators control. The rod 84 is pulled downwardly by any suitable means to overpower the spring l9 and normally serves to hold the guard mechanism in the position shown in Figure 8.

When the operator's control is moved to start the machine the rod 84 is moved upwardly, thus rocking the lever 83 on its pivot and allowing the spring 19 to move the clutch controlling member to the left having reference to Figure 8. By virtue of the pin 10 the cam lever 13 is also actuated in such a manner'that its other arm and :6i8xare connected :so as to have practically identical motion. It will also be noted that the member 11 isyinitia-lly in contact with the clutch member 516 at a considerable distance from its end; As the members H and 68 move, the lever 5.0; which is also associated with the pin 61, will revolve about its pivot GI and thus cause the guardxto. ,descendyon to the work. When the guard is down the length of the member H is such that it is still fully engaging the member The guard having made contact with the work, the members II. and 68 will continue their motion until the clutch is engaged, the guard in the meantime remaining in contact with the work by virtue of the resilientxconnection 63. The machine then starts and if the operators control remains in the setting on position the machine will continue to run, the guard system being then under the control of the cam H and the. spring 19, the cam being designed to functionexactlyas in the previous embodiment to raise and lower the guard at the appropriate time until such time as the operator stops the machine by movement of the. control or the guard is impeded from contacting with the work, whereupon the machineis stopped automatically by .full engagement between the members H and 56 as will be more fully described.

In Fig. 8 it may be observed that member 56 serves a similar purpose to that of member inFigs. 3 and 16 (to bedescribed).

Referring now to Figures to which show detailed views of the interlocking elements, Figure 10 shows the position of the parts with the ,machine at rest under the operators control.

Figure 11 shows the relative position of the interlocking elements when the guard reaches the work .and it will be evident that in this position the member 68 is free to pass to the position shown in Figure 12, at whichstage the clutch will be engaged. On completion of the insertion of the stitch the cam .17 positively returns the member 68 and also effects operation of thelever 60 and after retraction of the member 68 out of the path of the guard stem 59 will effect raisi ing of the guard from the work. In the case of. wire stitching machines it is advantageous owing ,to the high speed at which these machines often run and to the fact that the work has not to be re-inserted between consecutive stitches, so todesign the cam adapted to raise the guard that the latter is only partially raised to a position such as that shown in Figure 13. The operators control, however, always raises the guard to the position shown in Figure 10. Figures 10 to .13 show thenormal operation of the machine, that is if the guard motion is normal. If the guard motion is arrested at some point close to the work, as indicated in Figure 14, the interlocking member 68 is arrested and the member H connected with it is also arrested, whilst still fully extending across the path of the clutch engaging and disengaging member 55 (as shown in Figure 8) and the machine stops. It will be appreciated that the consideration already c referred to with regard to the possible force the inertia forces from the external connection guard falls belowthe level of the top of the work W W a second interlocking action will take place as shown in Figure 15, and consequently the machine cannot be started. The conditionof the machine then is that it cannot be started by the operators control unless the work is presented thereto and therefore the machine is automatically safe. It will be clear also that if the guard is removed the position of the interlocking members shown in Figure 15 will again be established and the machine cannot under any circumstances be started by the operators control while the guard elements 51 and 53 are not present.

It will also "be readily appreciated that if the slot is cut in a separate member secured to and adjustable on the guard stem 59, the position'orpositions of the range at which the safety lock would occur can be adjusted to suit any position of the top of the work within a designed range. This would applyto the case of machines with a fixed work support and a fixed throw of the operating mechanism, but with different thicknesses of material to be operated upon. In this form also theguard can be used both to protect against a pack of material of greater thicknesses than the safe amount being introduced, and also to make the machine inoperative if less than a given amount is introduced. This feature is vali uable in operating upon sheet material in packs.

It will be clear from the foregoing that the invention ,may be usefully applied to any type of machine driven by a one revolution clutch, in which the application of fixed guards is impracticable. i p

Although the clutch forms no part of the pres-; ent invention per se a typical form ofone revolution clutch, applicable to "either of the machines hereinbefore described, is illustrated. in Figs. 16 and 17 and will now be described with reference to its application to the embodiment shown in Figs. 1-7. In these Figures 16 and 17,

as in Figs. 1-7, ll] denotes the machine frame to the guard, apply as in the previously described Referring to Figure 11, it will be while 13 denotesit-he driving shaft with Which,-as

above indicated the clutch is associated. The shaft I3 is provided with a key on which are threaded-a flanged-collar 86 and a. slotted collar 81, both of which latter are keywayed to accommodate the key 85 while being held firmly against-a shoulder 88 on the-shaft l3 by means in a recess in the member 81 while the other en- I gages in a recess in the member 9| as clearly shown in Fig. 17. The outer face of the spring.

92 is adapted to carry a driving pulley 93.

As above described, when the clutch control member 59, which has been hereinbefore referred to with reference to Figs. 1-7, is in engagement with the member 41 which forms a nose or extension of the member 9|, the clutch will be disengaged since said member 9| will be held in a position wherein the diameterof the spring 92 will be such asto leave the driving pulley 93 running loose. As soon, however, as the member 56 is moved out of the path of the member 41 and. the member 9| isreleased the spring 92 which has intially been snapped into position on the' Mounted soas to be freely members 81 and'9l is able to expand into the bore of the pulley 93 whereupon the pulley and spring become substantially one member and the drive is transmitted by that lug on the end of the spring which engages the recess in the member 81 to said member 81 and so to the shaft l3. As soon as the member 9| is again arrested due to contact between the members 4'! and 50, which occurs in the manner hereinbefore more fully described, the spring 92 will be coiled up to its initial diameter which leaves the pulley 93 free of the shaft l3.

When applied to the machine illustrated in Figs, 8-15, the clutch constructed and operable in precisely the same manner as described with reference to Figs. 16-17, is mounted on the driving shaft 55 which is the equivalent of the shaft l3 While the clutch member 56 referred to in connection with the description of Figs. 8-15 will form the extension or nose of the member 9| with which extension or nose the member H is adapted to co-operate in the manner hereinbefore more fully described to effect engagement and disengagement of the clutch.

Finally, it will be appreciated that the form and disposition of the various members may be varied widely accordin to the type of machine to which they are applied without departing from the principle of supplying a pair of interlocking members interconnected with the clutch bolt and guard proper'respectively and also to the operators control and means for operating these elements from the machine mechanism independently of the operators control, one of said interlocking elements carrying the guard proper or being interconnected with a member carrying said guard.

What I claim and desire to secure by Letters Patent of the United States is:

1. A guard system for machines of the type having operating parts to be shielded, a driving clutch for communicating movement from drive means to said operating means, a guard operable as a part of every operative cycle of the machine and adapted to control the driving clutch and an operators control inter-connected with said guard, said system including a pair of co-acting members having mutually engageable surfaces which when in entire mutual contact prevent engagement of theclutch and means interposed between the guard and one of said members serving to ensure that said members can only be disengaged to allow engagement of the clutch by virtue of a relative movement over the whole of the mutually corresponding engaging surfaces of said members subsequent to the guard coming to rest in a safe position in any one of. a predetermined range of safe positions with respect to the aforesaid operating parts.

2. A guard system for machines of the type having operating parts to be shielded, a driving clutch for communicating movement from drive means to said operating means, a guard operable as a part of every operative cycle of the machine and adapted to control the driving clutch and an operator's control interconnected with said guard, said system including a member associated with the clutch, a second member adapted to cooperate with 'saidfirst mentioned member, both of said members having mutually engageable surfaces and adapted when in entire mutual contact to prevent engagement of the clutch, a pair of interlockable elements interposed between the guard and said second member, said elements when interlocked serving to prevent disengagement of said members and con: sequent engagement of the clutch and being controlled by the guard so that disengagement of the members cannot take place until the uard attains a safe position, disengagement of said elements resulting in subsequent disengagement of said members which move relatively to each other over the whole of the mutually corresponding engaging surfaces of said members.

3. A guard system according to claim 2 in which means are provided to cause a second interlocking action of the interlocking elements to take place to prevent engagement of the clutch if the guard passes beyond its predetermined safe position.

4. A guard system, according to claim 2, in which means are provided to effect automatic interlocking of the elements if the guard is removed from the machine.

5. A guard system for machines of the type having operating parts to be shielded, a driving clutch for communicating movement from drive means to said operating means, a guard operable as a part of every operative cycle of the ma chine and adapted to control the driving clutch and an operators control interconnected with said guard, said system including a member associated with the clutch, a pivoted member cooperating with said first-mentioned member, both of said members having mutually engageable surfaces, a spring tending normally to urge said pivoted member into entire mutual engagement with the first mentioned member to prevent engagement of the clutch and means operable automatically on the guard assuming a safe position subsequently to move said pivoted member against the action of said spring out of contact with the first mentioned member to allow engagement of the clutch, the relative movement between the two members taking place over the whole of the mutually corresponding engaging surfaces of said members.

6. A guard system for machines of the type having operating parts to be shielded, a driving clutch for communicating movement from drive means to said operating means, a guard operable as a part of every operative cycle of the machine and adapted to control the driving clutch and an operators control inter-connected with said guard, said system including a member associated with the clutch, a second member adapted to cooperate with said first mentioned member, both of said members having mutually engageable surfaces and adapted, when in entire mutual contact, to prevent engagement of the clutch, a pair of interlockable elements interposed between the guard and said second member said elements comprising a slidable element having a recess therein and a pivoted element which is arranged to move in a plane at right angles to the path of movement of the slidable element and is adapted to co-operate with the recess in the latter to provide the interlocking action, means operable by the guard to effect movement of the pivoted element and to cause disengagement of the same from the slidable element when the guard reaches a safe position, means adapted to impart movement to said slidable element subsequent to disengagement of the pivoted element therefrom and means associated with said slidable element adapted on such subsequent movement of said slidable element to actuate the second member and to move the same out of contact with the first mentioned member associated with the clutch to allow engagement of the latter.

7. A guard system for machines of the type having opera-ting parts to be shielded, a driving clutch for communicating movement from drive means to said operating means, a guard operable as a part of every operative cycle of the machine and adapted to control the driving clutch and an operators control interconnected with said guard, said system including a member associated with the clutch, a pivoted member cooperating with said first-mentioned member, both of said members having mutually engageable surfaces, 2. spring tending normally to urge said pivoted member into entire mutual engagement with the first-mentioned member to prevent engagement of the clutch, a pair of interlockable elements interposed between the guard and said second member, said elements comprising a slidable element having a recess therein and a pivoted element which is arranged to move in a plane at right angles to the path of movement of the slidable element and is adapted to co-operate with the recess in the latter to provide the interlocking action, means operable by the guard to effect movement of the pivoted element and to cause disengagement of the same from the slidable element when the guard reaches a safe position, means adapted to impart movement to said slidable element subsequent to disengagement of the pivoted element therefrom and means associated with said slidable element adapted on such subsequent movement of the latter to actuate the pivoted memher and to move the same against the action of the spring out of contact with the first mentioned member associated with the clutch to allow engagement of the latter.

8. A guard system for machines of the type having operating parts to be shielded, a driving clutch for communicating movement from drive means to said operating means, a guard operable as a part of every operative cycle of the machine and adapted to control the driving clutch and an operators control interconnected with J said guard, said system including a member associated with the clutch, a second member cooperating with said first-mentioned member, both of said members having mutually engageable surfaces, a spring tending normally to urge said second member into entire mutual engage ment with the first-mentioned member to prevent engagement of the clutch, a pair of inter! lockable elements interposed between the guard and said second member, said elements comprising a slidable element having a recess therein and a pivoted element which is arranged to move in a plane at right angles to the path of movement of the slidable element and is adapted to co-operate with the recess in the latter to provide the interlocking action, means operable by the guard to effect movement of the pivoted element and to cause disengagement of the same from the recess in the slidable element when the guard is in a safe position, resilient means associated with said slidable element adapted on disengagement of the pivoted element therefrom to impart a movement to the slidable element and a pin on said latter elementadapted after predetermined movement of the latter to engage the second member and to force the same to move out of engagement with the first-mentioned member associated with the clutch to allow engagement of the latter.

9; A guard system for machines of the type having operating parts to be shielded, a driving clutch for communicating movement from drive means to said operating means, a guard operable as a part of every operative cycle of the machine and adapted to control the driving clutch and an operators control interconnected with said guard, said system including a member associated with the clutch, a second member co-operatin'gwith said first-mentioned member, both of said members having mutually engageable surfaces, a spring tending normally to urge said second member into entire mutual engagement with the first-mentioned member to prevent engagement of the clutch, a pair of interlockable elements interposed between the guard and the second member, said elements comprising a slidable element having a recess therein and a pivoted element which is arranged to move in a plane at right angles to the path of movement of the slidable element and is adapted to co-operate with the recess in the latter to provide the locking action, means operable by the guard toeffect movement of the pivoted element and to cause disengagement of the same from the recess in the slidable element when the guard is in a safe position, a spring associated with said slidable element adapted on disengagement of the pivoted element therefrom to impart a movement to the slidable element, a pin associated with said latter element and adapted after predetermined movement of the same to engage the second member and to force the same tomove out of engagement with the first mentioned member associated with the clutch to allow engagement of the latter, a lever associated with the slidable element, a follower carried by said lever, and a cam carried by the driving shaft of the machine with which cam the follower on the lever is adapted to c'o-operate, said cam serving to control the operation of the guard and hence of the machine during the retention of the operators control in the starting position.

10; A guard system for machines of the type having operating parts to be shielded, a driving clutch for communicating movement from drive means to said operating means, a guard operable as a part of every operative cycle of the machine and adapted to control the driving clutch and an opera-tors control interconnected with said guard,

1 said system including a member associated with the clutch, a second member adapted to co-operate with said first-mentioned member, both said members having mutually engageable surfaces and adapted when in entire mutual contact to prevent engagement of the clutch, a pair of interlockable elements interposed between the guard and the second member, said elements comprising asli'dable element having a recess therein and a pivoted element which is arranged to move in a plane at right angles to the path of movement of the slidable element and is adapted to co-operate with the recess in the latter to provide the interlocking action, a spring associated with the pivoted element tending to urge same into its interlocking position, a lever associated with the guard and arranged to contact the pivoted element as the guard approaches its safe position and positively to move said pivoted element from engagement with the slidable element-means adapted to impart movement to the slidable element subsequent to disengagement of the pivoted element therefrom and means associated with said slidable element adapted on such subsequent movement to actuate the second member and to force the same out of contact with the first-mentioned member to allow engagement of the clutch.

11. A guard system for machines of the type having operating partsto be shielded, a driving clutch for communicating movement from drive means to said operating means, a guard operable as a part of every operative cycle of the machine and adapted to control the driving clutch and an operators control interconnected with said guard, said system including a member associated with the clutch, a second member adapted to cooperate with said first-mentioned member, both of said members having mutually engageable surfaces and adapted when in entire mutual contact to prevent engagement of the clutch, a pair of interlockable elements interposed between the guard and the second member, said elements comprising a slidable element having a recess therein, and a pivoted element which is arranged to move in a plane at right angles to the path of movement of the slidable element and is adapted to co-operate with the recess in the latter to provide the interlocking action, a spring tending to urge said pivoted element into its operative position, arockable shaft, an arm rigidly mounted on said shaft, a main spring associated with said 7 by said second arm from the safe position upon the reverse motion of the shaft, a third arm rigidly mounted on the shaft and angularly displaced with respect to the first, while being operatively connected with the slidable element, means operable by the guard when the latter approaches its safe position to efiect'movement of the pivoted element andto cause disengagement of the same from the slidable element, which latter is adapted on disengagement to be moved due to the action of the main spring to actuate the second member and to move the same out of engagement with the first-mentioned member associated with the clutch to allow engagement of the latter.

12. A guard system for machines of the type having operating parts to be shielded, a driving clutch for communicating movement from drive means to said operating means, a guard operable as a part of every operative cycle of the machine and adapted to control the driving clutch and an operators control interconnected with said guard, said system including a member associated with the clutch, a second member adapted to cooperate with said first-mentioned member, both of said members having mutually engageable surfaces and adapted when in entire mutual contact to prevent engagement of the clutch, a pair of interlockable elements interposed between the guard and the second member, said elements comprising a slidable element having a recess therein, and a pivoted element which is arranged to move in a plane at right angles to the path of movement of the slidable element and is adapted to co-operate with the recess in the latter to provide the interlocking action, a spring tending to urge said pivoted element into its operative position, a rockable shaft, an arm rigidly mounted on said shaft, a main spring associated with said arm with which latter the operators control is also associated, said main spring serving to rock the shaft on actuation of the operators control, a second arm associated with said shaft and resiliently connected with the guard so that on rocking of the shaft on actuation of the operators control the second arm will, due to the resilient connection, cause the guard to move into its safe position, said guard being positively moved by said second arm from the safe position upon the reverse motion of the shaft, a third arm rigidly mounted on the shaft and angularly displaced with respect to the first, while being operatively connected with the slidable element, a lever associated with the guard and arranged to contact the pivoted element as the guard approaches its safe position and positively to move said pivoted element against the action of its spring from engagement with the slidable element which latteris adapted on disengagement to be moved due to the action of the main spring to actuate the second member and to move the same out of engagement with the first-mentioned member associated with the clutch to allow engagement of the latter.

13. A guard system for machines of the type having operating parts to be shielded, a driving clutch for communicating movement from drive means to said operating means, a guard operable as a part of every operative cycle of the machine and adapted to control the driving clutch and an operators control interconnected with said guard, said system including a member associated with the clutch, a second member adapted to cooperate with said first-mentioned member, both of said members having mutually engageable surfaces and adapted when in entire mutual contact to prevent engagement of the clutch, a pair of interlockable elements interposed between the guard and the second member, said elements comprising a slidable element having a recess therein, and a pivoted element which is arranged to move in a plane at right angles to the path of movement of the slidable element and is adapted to co-operate with the recess in the latter to provide the interlocking action, a spring tending to urge said pivoted element into its operative position, a rockable shaft, an arm rigidly mounted on said shaft, a main spring associated with said arm with which latter the operators control is also associated, said main spring serving to rock the shaft on actuation of the operators control, a second arm associated with said shaft and resiliently connected with the guard so that on rocking of the shaft on actuation of the operators control the second arm will, due to the resilient connection, cause the guard to move into its safe position, said guard being positively moved by said second arm from the safe position upon the reverse motion of the shaft, a third arm rigidly mounted on the shaft and angularly displaced with respect to the first, while being operatively connected with the slidable element, a lever associatedwith the guard and arrangedto contact the pivoted element as the guard approaches its safe position and positively to move said pivoted element against the action of its spring from engagement with the slidable element which latter is adapted on disengagement to be moved due to the action of the main spring to actuate the second member and to move the same out of engagement with the first-mentioned member associated with the clutch to allow engagement of the latter, a lever associated with the slidable element, a follower carried by said lever, a cam carried by the driving shaft of the machine with which cam the follower is adapted to co-operate, said cam serving in conjunction with the main spring to control the operation of the guard and hence of the machine during the retention of the operators control in the starting position.

14. A guard system for machines of the type having operating parts to be shielded, a driving clutch for communicating movement from drive means to said operating means, a guard operable tending to urge said slidable member away from its operative position on actuation of the perators control, a pairof interlockable elements, one of which is associated with the guard while the second is capable of a sliding motion and is operatively connected to the slidable member, the two slidable members thus being capable of substantially identical motion, said first element having a slot therein which, when the guard is in its safe position, is so located with respect to the second element that the latter will move thereinto due to the action of the spring associated with the slidable member, said latter member when the second element moves into the slot also moving correspondingly to release the first mentioned member to allow engagement of the clutch.

15. A guard system for machines of the type having operating parts to be shielded, a driving clutch for communicating movement from drive means to said operating means, a guard operable as a part of every operative cycle of the machine and adapted to control the driving clutch and an operators control interconnected with said guard, said system including a member associated with the clutch, a slidable member adapted to cooperate with the first-mentioned member, a spring tending to urge the slidable member away from its operative position on actuation of the operators control, a pair of interlockable elements one of which is associated with the guard while the second is capable of a sliding motion and is operatively connected to the slidable member, the two slidable members thus being capable of substantially identical motion, said first element having a slot therein which, when the guard is in its safe position is so located with respect to the, second element that the latter will move thereinto due to the action of the spring associated with the slidable member, said latter member when the second element moves into the slot also moving correspondingly to release the firstmentioned member to allow engagement of the clutch, a pivoted arm operatively connected with said slidable member, a follower carried by said arm, a cam on the driving shaft of the machine with which the follower is adapted to co-operate, the arrangement being such that the cam, in conjunction with the spring, will control the operation of the machine during the retention of the operators control in the starting position.

16. A guard system for machines of the type having operating parts to be shielded, a driving clutch for communicating movement from drive means to said operating means, a guard operable as a part of every operative cycle of. the machine and adapted to control the driving clutch and an operators control interconnected with said guard, said system including a member associated with the clutch, a slidable member adapted to co-operate with the first-mentioned member, a spring tending to urge the slidable member away from its operative position on actuation of the operators control, a pair of interlockable elements one of whichis associated with the guard while the second is capable of a sliding motion and is operatively connected to the slidable member, the two slidable members thus being capable of substantially identical motion, a lever operatively connected with said second element, a resilient connection between said lever and the guard serving on operation of the operators control and consequent movement of the slidable member and of the slidable element to cause the guard to move into its operative position, said first element which is associated with the guard having a slot therein adapted, when the guard is in its safe position, to be so located with respect to the second element that the latter will move thereinto due to the action of the spring associated with the slidable member, said latter member when the second element moves into the slot also moving correspondingly to release the first-mentioned. member to allow engagement of the clutch.

17. A guard system for machines of the type having operating parts to be shielded, a driving clutch for communicating movement from drive means to said operating means, a guard operable as a part of every operative cycle of the machine and adapted to control the driving clutch and an operators control interconnected with said guard, said system including a member associated with the'clutch, a slidable member adapted to co-operate with the first-mentioned member, a spring tending to urge the slidable member away from its operative position on actuation of the operators control, a pair of interlocking elements one of which is associated with the guard while the second is capable of a sliding motion and is operatively connected to the slidable member, the two slidable members thus being capable of substantially identical motion, a lever operatively connected with said second element, a resilient connection between said lever and the guard serving on operation of the operators control and consequent movement of the slidable member and of the slidable element to cause the guard to move into its operative position, said first element which is associated with the guard having a slot therein adapted, when the guard is in its safe position, to be so located with respect tothe second element that the latter will move thereinto due to the action of the spring associated with the slidable member, said latter member when the second element moves into the slot also moving correspondingly to release the first-mentioned member to allow engagement of the clutch, a pivoted arm capable of actuation by the slidable member, a follower carried by said arm, a cam on the driving shaft of the machine with which the follower is adapted to co-operate on movement of said slidable member, the arrangement being such that the cam, in conjunction with the spring, will control the operation of the machine during the retention of the operators control in the starting position.

JOHN IRVING NASNHTH,