US2257090A - Strap sealing apparatus - Google Patents

Description

p 1941; w. c. CHILDRESS 2,257,090

STRAP SEALING APPARATUS Original Filed Nov. 16, 1936 5 Sheets-Sheet 1 P 1941- w. c. CHILDRESS 2,257,090

STRAP SEALING APPARATUS Original Filed Nov. 16, 1936 5 Sheets-Sheet 2 P w. c. CHILDRESS 2,257,090

STRAP SEALING APPARATUS Original Filed Nov. 16, 1936 5 Sheets-Sheet 3 Sept. 30, 1941. w, c, c ss 2,257,090

STRAP SEALING APPARATUS Original Filed Nov. 16, 1936 5 Sheets-Sheet 4 Patented Sept. 30, 1941 STRAP SEALING APPARATUS William C. Childress, Oak Park, 11]., assig'nor to Acme Steel Company, Chicago, Ill., a corporation of Illinois Original application November 16, 1936, Serial No.

Divided and this application August 19, 1938, Serial No. 225,680

6 Claim.

This invention relates to improvements in strap sealing apparatus and its purpose is to provide improved means for sealing the overlapping ends of a strap while it is held in a taut condition around a package or a group of packages. The present application is a division of the copending application Serial No. 111,088, filed November 16, 1936, now issued as patent No. 2,204,572, dated June 18, 1940, which describes and claims an electrically driven sealing tool embodying power driven means for drawing a flexible strap or binder taut around a package or the like, this strap stretching means being adapted to be employed in combination with the sealing means of the present invention, which performs the function of applying a seal to the overlapping strap ends and forming an interlocking joint.

The principal object of the present invention is to provide strap sealing mechanism comprising means for holding or gripping opposite end portions of the strap with its ends overlapping in combination with means for applying a seal to the overlapping strap ends after the strap has been drawn taut. A further object is to provide improved sealing mechanism comprising relatively movable jaws by which the seal is applied to the overlapping strap ends to form an interlocking joint, in combination with improved means for actuating the jaws. Still another object of the invention is to provide a sealing device adapted to be pivotally mounted upon a frame which may be the frame of the strap stretching device for drawing a strap taut around a package, whereby the sealing device may be swung to and from a position wherein its relatively movable jaws are adapted to embrace a seal applied to overlapping strap ends. Other objects relate to various features of construction and arrangement which will appear more fully hereinafter.

The nature of the invention will be understood from the following specification taken with the accompanying drawings in which one embodiment of the invention is illustrated. In the drawings;

'Figure 1 shows a top plan view of the improved strap sealing apparatus embodied in a combined strap stretching and sealing tool of the form disclosed in the original application above referred to;

Fig. 2 shows a side elevation of the apparatus illustrated in Fig. 1, with the strap -sealing apparatus and the strap gripping dog in their elevated positions;

Fig. 3 is a side elevation similar to that ol Fig. 2 showing a. gripping dog engaging one end of the strap and illustrating the position of the sealing device after it has been swung downwardly to bring the jaws thereof into engagement with a seal on the overlapping strap ends;

Fig. 4 shows an end elevation of the strap stretching and sealing apparatus looking toward the left as viewed in Fig. 1 and illustrating the position of the sealing head after it has been lowered to engage a seal on the overlapping strap ends;

Fig. 5 is an enlarged perspective view of the overlapping strap ends showing the application of a channel-shaped metal seal thereto before these parts have been acted upon by the sealing device to form an interlocking joint;

Fig. 6 is a perspective viewof the completed joint after the sealing device has bent the walls of the seal about the overlapping strap ends and has sheared the lateral edges of the strap and seal to form an interlocking joint;

Fig. 7 is a partial transverse vertical section taken on the line 'i--'| of Fig. 3;

Fig. 8 is a vertical section taken on the line 8-8 of Fig. 7;

Fig. 9 is a perspective View of the gripping dog shown in Figs. 2, 3, 7 and 8;

Fig. 10 is a perspective view of the eccentric on which the gripping dog is mounted together with a portion of its operating lever, a part of which is broken away;

Fig. 11 shows a perspective view, partly in section, of the sleeve in which are mounted the locking balls for controlling the movement of the lever and eccentric illustrated in Fig. 6;

Fig. 12 isa perspective view of the lower portion of the locking lever which is employed in conjunction with the parts shown in Figsv 10 and 11 to effect the locking and release of the eccentric on which the gripping dog is mounted;

Fig. 13 is an enlarged detail section taken on the line i3-l3 of Fig. 3 showing the assembled relationship of the parts illustrated in Figs. 10, 11 and 12;

Fig. 14 is a sectional view taken on the line "-44 of Fig. 8, showing the relative positions of the parts after they have been actuated to cause the locking members to hold the eccentric lever against angular movement;

Fig. 15 is a sectional view similar to that of Fig. 14 showing the relative positions of the parts after they have been actuated to secure the locking lever against angular movement;

Fig. 16 shows an enlarged detail section on the line lO-li of Fig. 4, illustrating the locking means for controlling the movement of the operating lever by which the sealing head is actuated;

Fig. 17 is a sectional view taken on the line Il-Il of Fig. 4, showing on an enlarged scale the relative positions of the parts of the locking means after they have been actuated to permit the downward angular. movement of the operating lever for effecting relative movement of the jaws of the sealing device;

Fig. 18 is a vertical section taken on the linell-IB of Fig. 17; g

Fig. 19 is a perspective view of the lower hub portion of the operating lever by which the sealing head is actuated;

Fig. 20 is a perspective view of the Supporting member upon which the sealing head is mounted;

Fig. 21 is a perspective view of the stationary member upon which the movable supporting member shown in Fig. 11 is mounted;

Fig. 22 is an enlarged vertical section taken on the line 22-22 of Fig. 4 showing the parts of the sealing head when it has been lowered to engage a seal on the overlapping strap ends;

Fig. 23 is a sectional view taken on the line 23-23 of Fig. 22 showing the relative positions of the jaws after they have been actuated to engage the seal;

Fig. 24 is a sectional view similar to that of Fig. 23, showing the relative positions of the jaws after they have been actuated to bend the walls of the seal upwardly beneath the overlapping strap ends and to shear the lateral edges of the strap and seal;

Fig. 25 shows a horizontal section taken on the line 25-25 of Fig. 24;

Fig. 26 shows a bottom plan view of the sealing head and adjacent parts when these parts are in the relative positions shown in Fig. 23; and

Fig. 27 is a vertical section taken on the line 21-21 of Fig. 25, showing the effect of the sealing jaws in/shearing the lateral edges of the strap and seal and deflecting edge portions thereof to form the type of interlocking joint shown in Fig. 6.

As shown in the drawings, the invention comprises a casing 35 adapted to rest upon the surface of a box or package 35 about which a flexible binder 31, shown as a flat steel strap, is adapted to be drawn taut preliminary to having its overlapping ends secured together by means of a seal which is deformed by a portion of the apparatus, simultaneously with the deformation of portions of the strap ends, to form an interlocking joint. The frame 35 is provided at its lower edge with two horizontally projecting feet or flanges 38 and 39 upon which the free end 31 of the strap is adapted to rest, as shown in Fig. 2. This free end portion of the strap is adapted to be held in engagement with the foot 38 by means of a gripping dog 40 which is capable of adjustment toward and from the foot for the purpose of gripping and releasing the strap. After being passed around the package 36, the other end portion 31 of the strap is passed into engagement with one of the transverse slots 4| 3 of a rotatable drum 4| by which thestrap is adapted to bedrawn taut about the package before applying thereto a seal 42 which is preferably constructed as a channel-shaped metal member adapted to embrace the overlapping end portions of the strap adjacent to the foot 39, the end portion 31 being projected beyond this foot a suflicient amount to permit the application of the seal at this point.

The drum n is adapted to be rotated through suitable driving mechanism actuated by an electric motor which is mounted in an auxiliary casing 3t carried at one side of the casing 35, as shown in Fig. 1. The casing 35 has a handle 43 which permits it to be carried around conveniently and to be located at any desired point on the surface of the box or package 36 to permit the application thereto of a strap 31. After the strap has been drawn taut by winding a portion of the strap on the drum 4|, the seal 42 is applied thereto to form an interlocking joint by means 01' a sealing head 44 which is pivoted on the upper part of the casing 35 adjacent one end of the handle 43 and which is adapted to be moved downwardly, by means of an operating lever 45, to a position where it embraces the seal 42 and the overlapping strap ends.

The gripping dog 40 is provided with a serrated portion 40 adapted to engage the upper surface of the strap 31 and this dog also has a horizontally extending cylindrical opening 40* which is rotatably engaged by a cam or eccentric member 41, having the form shown particularly in Fig. 10. This cam or eccentric member is provided with an eccentrically located opening 41 engaged by a pin 48 upon which the eccentric has angular movement. As shown in Fig. 7, the pin 43 is mounted in a bushing 43 located in a hub or bearing member l5 which is secured in the side of the casing 35 and the eccentric 41 is adapted to be rotated upon it in order to move the gripping dog 40 toward or from the end portion 31 of the strap. A threaded aperture 5| extends through the bearing member and through the bottom of the casing and is engaged by a headless screw 52 which passes through an aperture in the bushing 43 and has its extremity engaging a recess 48 in the pin, thus holding the pin against longitudinal or rotative movement. At its outer end, the pin 48 has an enlarged cylindrical portion 48 terminating in a flat head 48. A washer 53 is inserted between the enlarged portion 43 of the pin and the adjacent face of the eccentric or cam 41. A coil spring 54 surrounds the outer end portion 48 of the pin with one end 54* thereof engaging an aperture in the head 43 01 the pin and with the other extremity 54' thereof engaging an aperture 41 in the outer face of the eccentric 41 so that the spring tends normally to turn the eccentric ina direction adapted to swing the serrated portion lll of the gripping dog downwardly into engagement with the surface of the strap. The gripping dog 40 has a recess in the lower part thereof which is engaged by a movable block 55 and a coil spring 55 is mounted in this recess to force the block 55 normally against a lug 51 which forms a part of the casing 35. The spring-actuated block 3 55 thus tends to swing the gripping dog 40 in a counterclockwise direction, as viewed in Figs. 2, 3 and 8, so that the upright face 40 of the gripping dog bears against a stop screw 58 which is adjustably mounted in a lug 59 carried by the casing '35. A nut 60 is mounted on the projecting end of the stop screw 58 to secure it in adjusted position. The tension in the strap 31, being directed toward the left as viewed in Fig. 3, tends normally totighten the grip of the dog 40 upon the strap due to the fact that the serrated portion 40 of the gripping dog is offset toward the right, as viewed in that figure,

from a vertical plane passing through the axis about which the gripping dog pivots. When the tension upon the strap is relieved, the springactuated block 66 tends to swing the gripping dog about the eccentric so thatthe serrated portion 40- moves upwardly away from the surface of the strap, the extent of this angular movement of the gripping dog being capable of regulation by adjusting the position of the stop screw 58.

The cam or eccentric 41 is adapted to be moved about the pin 43 by means of a lever 62 which is secured to or formed integrally with the cam or eccentric, as illustratedin Fig. 10. The lever 62 is provided at its outer end with a transverse handle 62 adapted to be engaged by the fingers of the operator and it is provided adjacent the eccentric 41 with a laterally extending projection 62 having formed therein a recess 62, having a cone-shaped bottom, which is adapted to receive one of the two spherical balls 63 mounted in a flanged bushing 64, This bushing is mounted in a recess formed in the plate 35 of the casing which carries the feet 38 and 39, as shown in Fig. 13, and when the parts are in the position illustrated in this figure, the outer ball 63 engages the recess 62 to prevent angular movement of the cam or eccentric 41. The release of the lever 62 by the ball 63 is controlled by another lever 65 which has a handle 65* at one end thereof to be engaged by the fingers of the operator and which has an enlarged plate or hub 65 at the other end thereof provided with an aperture 65 which permits the lever to be journaled upon. the bushing 49 in which the pin 43 is secured. This plate 65 is further provided with a recess 65 in its outer side, having a cone-shaped bottom and when the lever 65 is in the position shown in Fig. the recess 65 is adapted to register with the bushing 64 so that the lever 62 may then be turned to force the balls inwardly and cause one of them to engage the recess 62 in the controlling lever. The controlling lever 65 is further provided between its ends with a transverse flange 65 having an aperture therein which is slidably engaged by a pin 66 and this pin is pivoted at 61 by a lug 58 carried by the casing 35, as shown in Figs. 2 and 3, and a coil spring 69 is mounted on this'pin 66 between the lug 68 and the flange 65 so that the spring tends normally to force the controlling lever toward the normal upright position shown in Fig. 3.

When the lever 65 is in the upright position shown in Fig. 3, the recess I55 in the hub portion thereof is out of registry with the bushing 64 and the balls 63 are thus held outwardly so that the outer one engages the recess 62 in the lever 62 and prevents rotation of the eccentric 41, thus holding the gripping dog 40 in a position where it grips the strap 31 as shown in Fig, 3. If the lever 65 is moved from the position shown in Fig. 3 toward the position shown in Fig. 2, with the resulting compression of the spring 69, a position is reached where the recess 65 registers with the balls 63 and the lever 62 may then be moved angularly with the result that the wall of the recess 62 forces the balls inwardly into the recess 65, as shown in Fig. 15, while the rotation of the lever 62 may be continued in an upward direction to cause the elevation of the gripping dog 40 out of engagement with the strap 31. When the lever 62 is again operated to rotate the eccentric and cause the dog to be lowered into engagement with the strap, the balls will again enter the recess 62 as the lever 65 is returned to its normal upright position by the action of the spring 69 so that the lever 62 will then again be locked in its lower position until the operator wishes to release the strap from the grip of the dog 40.

The drum 4|, upon which the end 31 of the strap is wound during the operation of drawing the strap taut around the, package, is joumaled in bushings mounted in bearing members carried by the casing 35 and the intermediate part of the drum is provided with a gear which is actuated by driving mechanism extending from the electric motor mounted in the auxiliary casing 35 previously referred to. When the strap has been drawn taut around the package to a predetermined degree, a clutch in the driving conneo-' tions is automatically disconnected so that a predetermined degree of tautness is maintained in the strap at the time that the seal is applied thereto. The motor is connected in an electric circuit which is preferably controlled by a switch having an operating member I6I mounted in the handle 43. The circuit of the motor also has connected therein a reversing switch having an operating handle I, shown in Fig. 2, which may be manipulated to reverse the direction of rotation of the drum 4| in order to loosen the strap wound therein preliminary to separating the strap from the drum after the joint has been formed.

The sealing head 44 by which the metal seal 42 is applied to the overlapping strap ends, oomprises a housin I20 having inner and outer side plates I20 between which are mounted a pair of sealing jaws I2I. These jaws are pivoted on pins I22 which extend through the side plates and which are engaged on the inner or under side of the sealing head by nuts I23. A bolt I24 extends through the side plates between the upper parts of the jaws and is engaged at its inner end by a nut I25. Each jaw I2I is made up of a .plurality of die plates including a series of bending dies I26 and a plurality of intermediate cutting or shearing dies I21. All of these dies are engaged by the pivot pins I22 and, in addition, they are restrained against relative angular movement by pins I28 which extend through registering apertures in the die plates of each jaw and which bear at their ends against the sideplates I'M) of the head. The bending dies I26 are provided along their lower inner parts with curved surfaces I26, concentric with the axes of the pivot pins I22, and these curved surfaces are adapted to engage correspondingly curved surfaces formed on a supporting member or saddle I29 which is mounted between the lower portions of the jaws, as shown in Fig. 23. This saddle I29 is provided at its ends with trunnions I29 which engage apertures I20 in the side plates for the purpose of supporting the saddle between the jaws. When the head 44 is lowered to the position shown in Figs. 22 and 23, the saddle I29 is adapted to rest on the back wall 42' of the seal and the parts are then in readiness for relative movement of the jaws I26 to move the pivot pin I22 for the purpose of bending the side walls 42 of the seal over the strap ends and then deforming the lateral edges of the strap and seal to provide an interlocking joint. In order to operate upon a seal and the strap end in this manner, the bending dies I26 are provided at their lower ends with curved hooked portions I26 which are adapted to engage the side walls 42 of the seal to bend them upwardly and inwardly from the position shown in Fig. 23 to that shown in Fig. 24. The shearing dies I21 which are mounted between the bending dies are provided at their lower ends with cuttingv edges I2I which, during the relative inward movement of the portions of the jaws, are adapted to act upon the lateral edges of the overlapping. strap and seal to shear the metal transversely, as shown at I30 in Fig. 6, while at the same time deflecting the metal between adjacent cuts to form in-- clined lugs I3I. In this way an interlocking joint is formed between the seal and thelstrap ends.

The upper ends of the bending dies I26 of each Jaw extend beyond the upper extremities of the shearing dies I21 and these projecting portions of the bending dies are adapted to receive between them the lower ends of a'pair of links I33 to which they. are pivotally connected by pins I34. These links converge upwardly and are pivotally connected at their upper ends by a single pin I35 to the depending flanges I36 of the rack bar I36 which is mounted to reciprocate between the upper portions of the side plates I20. When the rack bar is forced downwardly, it causes the lower ends of the links I33 t separate from the position shown in Fig. 23 to the position shown in Fig. 24, thereby causing a corresponding inward movement of the lower portions of the jaws. This movement of the rack bar I33 is effected by a pinion I31 which is mounted upon a shaft I38 loumaled in the upper transverse bars I30 of the head 44. These bars I39 and also the inwardly extending projection I20 of the inner side plate are joumaled upon a pin or bolt I40 which is secured in a stationary position in a bracket I carried by the end of the casing 35. In this way, the head 44 is adapted to swing bodily about the pin I40 in moving from the elevated position shown in Fig. 2 to the position shown in Figs. 22 and 23, where the lower portionsrof the jaws embrace the seal 42 on the overlapping strap ends. In addition to this bodily movement of the head 44, the jaws I2I have the relative angular movement previously referred to for the purpose of bending and deforming the seal and the overlapping strap ends, and it is desirable'that both of these movements of the head and of the jaws be effected by the single operating lever 45, previously referred to. For this purpose, the lever 45 is keyed upon the projecting end of the shaft I 38 which carries the pinion I 31 for actuating the jaws, and connections are provided whereby this lever may also be utilized for swinging the head 44 about the pin I40 without at the same time effecting relative movement of the jaws.

The locking mechanism for bringing this about includes a locking bar I43 which is pivotally mounted upon the pin I40 and which is also pivotally engaged by the projecting end of the shaft I38. The shaft may be provided with an angular groove I 33 to receive a pin I42 which is secured in the member I43. The bar I43 is provided between the pin I40 and the shaft I38 with a cylindrical opening I 43 extending completely therethrough and adapted to receive a pair of spherical balls I44. These balls are adapted to move partially out of the opening I4I into the recess 45. formed in the side face of the hub of the operating lever 45 or into another similar recess I45 which is formed in the side face of a block I45 mounted in a fixed position adjacent the bracket I. When the head 44 is in its uppermost position, as shown in Fig. 2, the lever 45 is in the positionshown in that figure, and one of the balls is adapted to extend into the recess 45 in the hub of the operating lever, while the other end of the opening min the locking bar is closed by the end face of the block I45 so that an upward movement of the lever 40 toward the right, as viewed in Fig. 2, would then swing the head 44 bodily downward about the pin I40 to position the Jaws over the seal on the overlapping strap ends, as shown in Figs. 3 and 23. As the limit of this bodily movement is reached, the bar I43'will reach the position shown in Fig. 16 where the balls I44 will register with the recess I 45 in the block I 45 and the wall of the recess I45 will then exert a wedgingaction upon the coacting ball to cause the balls to move toward the right, asviewed in Fig. 16, until one of these balls engages the recess I45 and until the other ball is free of the recess 45. The lever 45 will then be free to turn with respect to the locking bar I43 and the continued motion of the lever 44 in the same direction will cause relative movement of the jaw I2I through the pinion I31 and the rack bar I36, thereby bending the seal and deforming the edges of the strap and seal. When the sealing operation has been completed, the lever 45 will be moved upwardly with the result that the initial motion thereof will cause the lower portions of the jaws to separate from each other and when this separation has reached the point where the upper parts of the jaws engage the transverse bolt I24, further angular movement of the operating lever 45 about the pivotal axis of the shaft I38 will be prevented and further pressure on the lever will cause the entire head 44 to move bodily upward about the pivot I40. During this upward movement of the lever 45, a point will be reached where both recesses 45". and H5 will align with the balls I44 and the bodily movement of the head will cause the wall of recess I45 to force the balls partially into the recess 45 as the upward bodily swinging movement of the head 44 continues, so that when the head reaches its upper position, the operating lever 45 will be locked to the locking bar I43in readiness for the next downward swinging movement of the head. I

In the operation of the device, the end 31 of the strap is first placed over the foot or flange 38'and the lever 62 is operated to move the gripping dog 40 downwardly into engagement with the strap. When this has been done, the controlling lever 65 is operated to cause the ball 63 to lock the lever 62 to prevent its actuation for elevating the gripping dog from the gripping position. The strap is then passed around the package and the other end portion 31 thereof is passed transversely through one of the slots in the end of the winding drum H. The operator then operates the switch member I6I on the handle 43 to cause the motor to be actuated, with the result that the drum M is turned and the strap is gradually wound thereon as it is tightened around the package 36. When a predetermined tension has been set up in the strap, the clutch in the driving mechanism operates to discontinue the driving mechanism, as explained in the original application above referred to. After the strap has thus been drawn taut, a seal 42 is placed over the overlapping strap ends and the lever 45 is actuated to swing the sealing head 44 downwardly and then to operate the jaws I2I of the head to form an interlocking joint between the seal and the strap ends. It may then be desirable to reverse the direction of rotation of the motor in order to loosen the strap which has been wound on the drum 4| and this may be done by actuating the switch handle I'M to cause a short period of reverse rotation of the drum. The motor is then stopped and the end portion of the strap which has been in engagement with the drum may be removed therefrom by sliding the casing 35 sidewise and first be desirable to release the gripping dog 40 from the strap so that the entire casing may be removed laterally with respect to the strap, and this may be done by actuating the controlling lever 65 to permit the balls 63 to move out of their locking engagement with the lever 62, whereupon, the lever 62 may be actuated to rotate the eccentric 41 and cause the elevation of the gripping dog 40 which will then tilt automatically toward the right, as viewed in Fig. 2, under the influence oi the spring 55 so that the serrations 40 will move out of engagement with the surface of the strap.

Although one form of the invention has been shown and described by wayof illustration, it will be understood that it may be constructed in various other embodiments coming within the scope of the appended claims.

I claim:

1. The combination in a strap sealing device for uniting overlapping strap ends, of a casing, a sealing device pivotally mounted on said-casing for movement toward and from said strap ends and comprising a pair of relatively movable jaws, a rack and pinion for eilecting relative movement of said jaws, a lever for operating said pinion, said lever having a recess, a stationary member mounted adjacent the pivot of said sealing device and having a recess therein, and a bar mounted between said lever and said stationary member and having an aperture adapted tion, a locking bar mounted on said pin and adapted to swing with said sealing device, and means actuated when said locking bar is in a a stationary block mounted adjacent said looking bar and having a recess therein, said lever having a recess therein, said locking bar having an aperture therethrough, and locking members mounted in said aperture and adapted to engage said recesses to lock said lever against movement with respect to said sealing device when said sealing device is in a predetermined position and to lock said sealing device against pivotal movement while permitting relative movement of said lever with respect to said sealing device when said sealing device is in another position.

4. The combination in a strap sealing apparatus of a casing, a sealing device pivotally mounted on said casing and comprising a pair of relatively movable jaws, a rack and pinion for effecting relative movement of said jaws, a lever for operating said pinion, said lever having a recess, a stationary member mounted adjacent the shaft of said sealing device and having a recess therein, a bar mounted between said lever and said stationary member and having an aperture therethrough, and balls mounted in said aperture, said aperture being adapted to register with said recesses.

5. The combination in a strap sealing apparatus, of a casing, a sealing device, a pin carried by said casing and having said sealing device pivotally mounted thereon, a second pin carried by said sealing device, a lever fixed on said last named pin for actuating said sealing device when it is in its operative position, a locking bar pivotallymounted on each of said pins and arranged to swing with said sealing device about said first named pin, and means actuated when said lever and said locking bar are in predetermined relative positions for holdingsaid lever w to contain a pluralityof balls, said aperture be-' predetermined position for locking said lever against angular movement with respect to said sealing device.

3. The combination in a strap sealing apparatus, of a casing, a sealing device, a pin on which said sealing device is pivotally mounted, a lever carried by said sealing device for actuating said sealing device when it is in operative position, a locking bar mounted on said pivot and adapted to swing with said sealing device,

against angular movement with respect to said sealing device.

6. The combination in a strap sealing apparatus, 01' a casing, a sealing device, a pin carried by said casing and having said sealing device pivotally mounted thereon, a second pin carried by said sealing device, a lever fixed on said last named pin for actuating said sealing device when /it is in its operative position, a locking-bar pivotally mounted on each or said pins and arranged to swing with said sealing device about said first named pin, means actuated when said locking bar is in one position with respect to said lever for holding said lever against angular movement with respectto said sealing device and actuated when said locking bar is in another position for permitting angular movement or said lever with respect to said sealing device and holding said locking bar against further pivotal' movement, and means actuated by said second named pin-tor operating said sealing device by the relative angular movement of said

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