EP0207073A4 - Conveyor systems. - Google Patents

Abstract

Systems for conveying articles of a parallelepipedal or generally parallelepipedal configuration from a first location (A) to a second location (B). The systems include a gripper conveyor (20) and an ancillary system (30, 32) which insures that the gripper assemblies (34) will securely seize successive articles delivered to the conveyor as the gripper assemblies move at high speed past an article pick-up point (A). A novel gripper assembly construction, emergency deflection (D) of articles from the gripper conveyor, single article or small count drop-off of articles along the conveyor route, adjustments to accommodate articles of different thicknesses and cut-off lengths, a linear drive system (140, 142) which reduces loads on the moveable conveyor components, and gripper assembly associated and incorporated mechanisms (230) which insure that the jaws of the gripper assemblies both remain closed and positively open during specified portions of their operating cycle are among the other salient features which the article conveyor systems disclosed herein or sub-systems of the latter may have.

Description

CONVEYOR SYSTEMS

TECHNICAL FIELD OF THE INVENTION

The presentinvention relates to conveyor systems and, more particularly, to novel, improved systems for conveying parallelepipedal or generally parallelepipedal articles at high speed from one location to another.

At the present time, the perhaps most commercially important application of the invention is in the transfer of newspapers or newspaper inserts from an infeed conveyor to a drop-off conveyor.

The infeed conveyor, in a typical application of the invention, delivers newspapers or newspaper inserts from a press room to a conveyor system as disclosed herein. That conveyor system, located in the mail room of the printing establishment, transfers the articles 300 feet or more and to a different level to the drop-off conveyor which feeds a stacker or inserter in newspaper handling applications of the invention.

The term "insert" appearing above and hereinafter is employed in the usual sense to include both magazines, advertisements, and the like and those separate sections of a Sunday or other larger paper. Such papers will typically exceed the 160 page maximum of a modern, high speed press. Consequently, one or more inserts of specified sections will also be printed and inserted in the paper before it is delivered to the stacker.

BRIEF DESCRIPTION OF THE INVENTION

The conveyor systems disclosed herein feature a novel, superior gripper conveyor for transferring the articles ^• being handled from the infeed conveyor to the drop-off conveyor. Those gripper conveyors have grippers that can be locked in any one of an essentially unlimited number of positions with a force which can be varied as needed from ^"application-to-appliσation of the invention. Relatively simple mechanisms including an off-the-shelf, one-way spring clutch can be used to insure that the jaws of the gripper assemblies remain positively closed during the article transfer portion of the operating cycle and open in an equally superior fashion and with a minimum of shock loading at the drop-off point. The consequence of these features is that the gripper conveyors disclosed herein operate reliably and, because the forces exerted on the articles being handled can be tailored to the article thickness, with minimized strain on and wear of the gripper assemblies.

Provision is also made in the novel conveyor systems disclosed herein for deflecting articles away from the gripper conveyor in abnormal situations to prevent damage to that conveyor. Such situations include jams in the gripper con¬ veyor and those malfunctions of the press or presses supply¬ ing the conveyor systems which necessitate an emergency shutdown of the press. This conveyor is also constructed to accαmiodate two or more stacked aritcles arriving together on the infeed conveyor, eliminating the jam which might other¬ wise occur in such circumstances.

In typical applications of the invention, such as those discussed above, the efficiency of the conveyor system as disclosed herein will depend upon the gripper conveyor of that assembly seizing and carrying away the articles trans¬ ferred to it at a spacing or pitch differing from that-at which those typically imbricated articles are delivered from the press by the infeed conveyor (by "pitch" is meant the distance between the leading edges of successive articles) . This may differ by several inches, and it is accordingly significant that the conveyor systems disclosed herein are capable of changing the pitch of the articles supplied to them from an infeed conveyor to the gripper conveyor pitch simply and in a manner which will insure that those articles are securely siezed by the gripper assemblies.

The transfer conveyors employed in the herein disclosed systems to insure that the articles being transferred arrive at the gripper conveyor with the correct pitch deliver the articles to the gripper conveyor pickup point at an inclined angle, i.e., in an uphill orientation to insure that those articles will be securely seized by the gripper assemblies. So that the articles will be properly delivered to this up¬ wardly inclined transfer conveyor, the novel conveyor systems disclosed herein also feature a force feed system which forwards those articles to the transfer conveyor in a manner that permits the latter to positivley engage and deliver them to the gripper conveyor. Absent this innovation, the articles being conveyed might well slip back down the transfer conveyor, causing a jam or similar malfunction.

The transfer conveyor, typically of the lug belt type, is also preferably pivoted about its feed end or otherwise so constructed that the upper, discharge end of the conveyor can be vertically displaced. The provision for vertical adjustment can be taken advantage of to insure that articles of different thicknesses will be properly positioned between the jaws of the conveyor' gripper assemblies before the latter are closed upon those articles.

In newspaper conveying and similar applications of the present invention, it is desirable to provide for a single article or smaller number of articles (termed "check copies" in the industry and used to check registration, etc.) to be dropped off, upon demand, at a specified location different from the main drop-off point. Another advantage of the novel conveyor systems disclosed therein is that they are readily capable of achieving this objective, even at the extra¬ ordinarily high speeds at which such conveyor systems are typically operated (up to 80,00 articles per hour).

Still another important advantage of the conveyor systems dislcosed herein is a linear drive system which equalizes the loads imposed upon the assemblies of the gripper conveyor as well as the loads upon each individual assembly. WO 86/03476 _₄_ PCT/US84/02006-

This novel drive arrangement is important in that it substan¬ tially extends the service life of those gripper conveyor com¬ ponents most subject to wear.

Yet another innovative feature of the conveyor systems dis¬ closed herein is an arrangement by which the relationship of the gripper conveyor assemblies and the lug belt conveyor can be so adjusted as to accommodate articles with different cut-off lengths (that term is employed herein as in the technologies to which the present invention relates to designate the distance between the leading and trailing edges of the article being con¬ veyed) . This advantageously adds to the versatility of the con¬ veyor system. BACKGROUND ART

Conveyor systems and conveyor systems components which superficially resemble those discussed above are disclosed in U.S. Patent Nos.: 3,443,308 issued May 13, 1969 to Siebke for SHEET GRIPPER MECHANISM; 4,062,537 issued December 13, 1977, to Dietrich for APPARATUS FOR THE INFEED OF PRINTED PRODUCTS TO A STACKER; 4,224,873 issued September 30, 1980, to Wieland for CLAMPING GRIPPER; 4,253,986 issued March 3, 1981 to Wieland for SHEET GRIPPER; 4,307,801 issued December 29, 1981, to Hansch for CONVEYOR APPARATUS FOR SUBSTANTIALLY FLAT PRODUCTS, ESPECIALLY PRINTED PRODUCTS; 4,333,559 issued June 8, 1982, to Reist for APPARATUS FOR INFEEDING FLAT PRODUCTS, ESPECIALLY PRINTED PRO¬ DUCTS, ARRIVING IN AN IMBRICATED STREAM TO A TRANSPORT DEVICE; 4,372,209 issued February 8, 1983, to Jentziech et al for SHEET GRIPPING JAW ARRANGEMENT; and 4,381,056 issued April 26, 1983, to Eberle for CONVEYOR APPARATUS, ESPECIALLY FOR PRINTED PRODUCTS. Only a limited review of the foregoing, previously issued patents is needed, however, to convince one that the resemblances in question are no more than superficial. As a single example, the most recently issued, and therefore ostensibly most technologically advanced gripper arrangement, is that disclosed in Eberle patent No. 4,381,056. Nevertheless, despite its apDarently relatively recent origin, the Eberle arrangement is far inferior to that disclosed herein in that the movable jaws of Eberle's gripper assemblies have only a single position to which they can be closed with respect to the fixed jaws of the assemblies. To accommodate both thin and thicker articles, this position must be so selected that the thinner articles will be effectivel gripped. This results in high stresses being imposed upon the gripper assembly components when thicker articles are being handled, causingthose components to wear at a rate which is reduced substantially by the novel force and position adjustable gripper arrangements diclosed. herein.

OBJECTS OF THE INVENTION

From the foregoing, it will be apparent to the reader that the primary object of the present invention resides in the provision ofnovel, improved systems for conveying articles of parallelepipedal and generally parallelepipedal configuration from one location to another.

Other also important, but more specific, objects of the invention reside in the provision of conveyor systems as just described: which can transfer the articles being handled over relatively long distances and from one elevation to another reliably and at high speeds; which can handle, with equal facility, articles varying in thickness by an order of magnitude or more; which are so constructed as to minimize wear on those system components most subject to wear, thereby substantially increasing the service life of those components; which are capable of diverting articles away from major system components if a malfunction occurs, thereby protecting those components against the damage which might otherwise result which, in addition to being readily adjustable to accommodate articles of different thicknesses, can with equal facility be programmed to handle articles of different top- to-bottom lengths; which are capable of accepting articles at one pitch andspacing and delivering those articles to a conveyor designed to accept those articles at a different pitch; which are so constructed that a single article, or a small number of articles, can, upon demand, be dropped off at any given location along the conveyor system route.

As discussed above, one of the major components or subsystems of the novel conveyor arrangements disclosed herein is a conveyor of the gripper type employed to transfer the articles being handled over the major part of the path travelled by those articles. Another important and primary object of the inventionresides in the provision of novel, improved gripper conveyors for transferring articles in a specified orientation along a path of determined configura¬ tion which may include both horizontal and vertical components and in the provision of novel, improved gripper assemblies for such conveyors.

Again related and important, but more specific, objects of the invention reside in the provision of such conveyors and gripper assemblies therefor: which have a serially arranged complement of gripper assemblies and in which those assemblies are driven in a manner that tends to equalize the loads on the several assemblies and those loads imposed upon the components of each individual assembly; in which, in accord with the preceding object, the gripper assemblies are driven in a manner that is simple and yet affords effective connections between the gripper assem¬ blies and the mechanism employed to drive them; in which the gripper assemblies are cam operated and in which the operating mechanism can be simply and accurately adjusted to limit the force imposed by the gripper assemblies on the articles being transferred; in which the gripper assemblies each have a fixed jaw, a oveable jaw, and a clutch mechanism for locking the moveable jaw in any one of an essentially infinite number of positions relative to the fixed jaw to retain the effectiveness with which the gripper assemblies are capable of seizing articles of different thickness while minimizing stresses on the gripper assembly components; in which the moveable jaw is locked in a closed position as aforesaid by a^' one-way spring clutch; in which the conveyor's clutch operating mechanism is so constructed as to eliminate forces that might be of sufficient magnitude as to open the clutch prematurely; which include an unlocking, or jaw opening, mechanism that will effectively insure that the assembly jaws are fully opened at the drop-off point or points at high speed operation.

Other important objects and features and additional advantages of the application will be apparent from the fore¬ going, from the appended claims, and from the ensuing detailed description and discussion of the invention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

Fig. 1 is a generally pictorial layout of a conveyor system constructed in accord with, and embodying, the principles of the present invention;

Fig. 2 is a partial, partly schematic, side view of the conveyor system;

Fig. 2A a fragmentary plan view of a lug belt conveyor incorporated in the conveyor system of Fig. 1;

Fig. 3 is a fragmentary, pictorial view of a gripper conveyor constituting a major subsystem of the conveyor system shown in Fig. 2;

Fig. 3A is an elevation of one of a serially connected complement of truck assembly, gripper assembly combinations which are constituents of the gripper conveyor; Fig. 4 is a fragmentary view showing, in elevation, two of the serially connected gripper assemblies employed in the system of Fig. 3;

Fig. 5 is an elevation of a gripper assembly taken at right angles to Fig. 3A, it also shows details of the acco- ciated truck assembly employed to guide the gripper assembly along a conveyor system track such as that shown in Fig. 1;

Fig. 6 is a side elevation of a cam-type mechanism employed in the gripper conveyor to actuate jaw closing mechanisms incorporated in the gripper assemblies;

Fig. 7 is an end view of the actuating mechanism;

Fig. 8 is an elevation of a drive mechanism incorporated in the gripper conveyor to displace the gripper assemblies of the latter along a track such as that shown in Fig. 1;

Fig. 9 is a top view of the drive mechanism;

Fig. 10 is an elevation of mechanism employed in the gripper conveyor which cooperates with an also illustrated release mechanism in each gripper assembly to cause the jaws of that assembly to open as it reaches an article drop¬ off point; and

Fig. 11 is a partial section through a gripper assembly, showing a clutch mechanism incorporated in that assembly to lock the jaws of the latter in any one of an essentially infinite var of closed positions and mechanism for releasing the clutch and allowing the jaws to open at an article drop-off point. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Referring now to the drawings, Fig. 1 is a layout of a conveyor system 20 constructed in accord with, and embodying, the principles of the present invention; and Fig. 2 shows the major components of that system. These include a gripper conveyor 22 for conveying articles of a parallelepipedal or generally parallelepipedal configuration over an extended distance and through a change in elevation from an infeed conveyor 24 to a drop-off conveyor 26. The infeed conveyor, typically of the endless tape type, may, in a prominent applicaiton of the invention, be employed to transfer news- papers or inserts from the folder of a high ^'speed press to conveyor system 20, passing from a pressroom to a ailroom isolated therefrom as it does so. The infeed conveyor is not. part of the present invention, and conveyors of this character are commercially available. Therefore, the infeed conveyor will be referred to hereinafter only to the extent necessary for an appreciation of the present invention.

Drop-off conveyor 26 is, likewise, not a component of the exemplary conveyor system disclosed herein. Instead, it is designed to receive articles from that conveyor and, in a typical application of the type under discussion, deliver those articles to a stacker or to an inserter where the news¬ paper is assembled before it is delivered to the stacker. Again, inserters, stackers, and tape, wire, or belt type conveyors such as that identified by reference character 26 in Fig. 1 are commercially available, are not part of the present invention, and will not be descsribed further herein except in their relationship to conveyor system 20.

Referring now specifically to Fig. 2, conveyor system 20 includes, in addition to the gripper conveyor 22 identified above, an emergency exit conveyor 28, a force feed conveyor 30 located at the downstream or delivery end of the latter and a lug belt conveyor 32 for transferring articles delivered to it by the force feed conveyor to the gripper assemblies (see, also, Fig. 3) of gripper conveyor 22.

Referring again to Fig. 1, gripper conveyor 22 is employed to transfer the articles being handled over all but a few feet of the up to several hundred feet and one or more changes in elevation from the infeed conveyor to the drop-off conveyor. The points at which the gripper conveyor picks up and drops off articles being handled by it are identified by reference characters "A" and "B" in Fig. 1.

It will be appreciated by those skilled in the arts to which this invention relates from the foregoing that the gripper conveyor is typically the most significant conveyor subsystem from the cost point-of-view, at least. Emergency exit conveyor 28 is σonequently provided to protect the gripper conveyor against the damage to it which might otherwise result from a jam in the gripper conveyor or an emergency press shutdown and consequent abnormal influx of articles from the press via infeed conveyor 24.

The illustrated, exemplary, emergency conveyor includes one or more endless wires, tapes, or belts 35 trained around horizontally oriented, transversely extending rotating members such as rolls 36 and 38 at the lower, feed end and upper, delivery end of the emergency exit conveyor. The emergency exit conveyor is mounted for pivotal movement about a hori¬ zontal axis at its lower, infeed end via a shaft 40 which carries rotatable drive member 36. The upper end of the emergency exit conveyor is displaceable between an operative position in which it is capable of transferring articles being handled onward for delivery to gripper conveyor 22 and a position in which those articles are instead dumped onto the floor behind conveyor system 20 or into a discharge chute (not shown) or otherwise deflected away from the gripper conveyor to prevent damage to the latter. The operative and dump positions of the emergency exit conveyor are identified by reference characters "C" and "D" in Fig. 2.

The upper end of the emergency exit conveyor is supported for movement between the operative and dump positions just described by pneumatic cylinders 42 at opposite sides of the conveyor (only one of which is shown) . The pneumatic cylinders are supported from the framework 46 of conveyor system 20. The details of the latter, are, again, not part of the present invention; and the framework will accordingly be described hereinafter only to the extent necessary for an understanding of the invention.

Each pneumatic cylinder 42 has a piston rod (not shown) connected through a clevis 48 to the conveyor. Consequently, by admitting fluid to the upper ends of the pneumatic cylinders, the conveyor can be pivoted downwardly to the dump position D. Conversely, by supplying fluid to the lower ends of the cylinders the conveyor can be rotated upwardly in a counterclockwise direction to the operative, "C", position.

To insure that the articles do not slip as they move up the emergency exit conveyor, a normal biasing force is imposed upon them. This is provided by a companion, endless wire, tape, or belt system 50 having a lower run 52 which parallels the upper run 54 of the emergency exit conveyor. This force applying, cover system (which includes details that are not part of the present invention) is supported from the framework 46 of conveyor system 20 at both its lower and upper ends by support assemblies 56. As shown in Fig. 2, these assemblies are of the adjusting screw type. These are used to raise and lower the cover system for articles of different thicknesses.

Furthermore, each of these support assemblies preferably includes a flexible link 58. In newspaper handling (and other) applications of the present invention, two or more superimposed or stacked articles may simultaneously be delivered to the emergency exit conveyor by infeed conveyor 24. The flexible links allows the cover assembly to move upward and accommodate such anomalies without interfering with the biasing action which the assembly provides.

As is apparent from Fig. 2, the articles being handled by system 20 are delivered from the emergency exit conveyor to the (typically lug belt type) transfer conveyor 32. Force feed system 30 insures that the articles will be propelled sufficiently far along the transfer conveyor to insure engage¬ ment between that conveyor's lugs and the upstream, lower, trailing edges of the articles. The force feed system includes an endless belt 60 trained around rolls 62 and 64 and a transversely extending roll 68 which is preferably faced with a soft, resilient material to create a strong gripping force at the nip 70 between that roll and the upper end of endless belt 60. Articles passing through the nip 70 between the softly surfaced roll 68 and driven belt 60 are accordingly positively propelled sufficiently far along conveyor 32 to be securely engaged by the lugs of that conveyor.

Lug belt conveyor 32 is not shown in detail herein be¬ cause, again, the details of this system are not part of the invention. In general, this conveyor includes a lower roll driven by a sprocket 72 and a freely rotatable upper roll (not shown) around which two or more transversely spaced, endless chains 74 (see Fig. 2A) are trained. These chains carry lugs 76 designed to engage the lower, trailing edges of the articles 78 being handled by the conveyor system 20. The illustrated conveyor has disappearing lugs; i.e., lugs which rotate downwar toward their supporting chains as they reach the upper end of t conveyor. This system is not necessary, however; a conveyor wi fixed lugs can equally well be employed.

The moving components of the emergency exit conveyor and force feed conveyor described above are commonly powered by a motor 79 (see Fig. 2) and a drive chain system identified generally by reference character 79A in that Figure. Once agai this system is one that will not be described in detail herein because its particulars are not part of the present invention a because an appropriate arrangement of the illustrated, endless chain or belt system will be apparent to those skilled in the relevant arts from Fig. 2.

It is the function of conveyor 32 to so transfer the articles arriving on infeed conveyor 24 to gripper conveyor 22 a manner that the articles can be securely seized by the grippe assemblies 34 of the latter. The lug belt conveyor also con¬ tributes to the versatility of the novel conveyor systems dis¬ closed herein in that it can be employed to insure that article of different thicknesses and cut-off lengths are properly positioned with respect to the gripper conveyor assemblies when the latter are closed. In the same vein, this conveyor is also used to change and match the pitch of the imbricated articles arriving on infeed conveyor 24 to the generally different pitch (typically three vs. six inches) of the gripper conveyor. That this match can be made is an important practical feature of the present invention because press and conveyor system operating pari aters require those differing pitches for operating efficiency.

Yet another important feature of the conveyor system disclosed herein is that the speeds of the lug belt and gripper conveyors can be precisely, and adjustably, related. This makes conveyor system 20 capable of handling articles with different cut-off lengths.

As shown in Fig. 2, the lug belt conveyor is pivotally supported at its lower end for rotation- about a transversely extending, horizontal axis by shaft 80. The latter also supports the lug belt conveyor drive sprocket 72.

The upper, delivery end of this inclined, transfer conveyor is supported for vertical movement about the horizontal axis just described by pneumatic cylinders at opposite sides of that conveyor. One of these is shown in Fig. 2 and identified by reference character 82. By admitting a pneumatic fluid to, and bleeding it from, these cylinders, the upper end of the lug belt conveyor can be so vertically adjusted that the leading edges of articles of different thicknesses will be precisely aligned with the gripper assemblies 34 of conveyor 22 in the manner shown in Fig. 4 as the articles reach the feed end of the gripper conveyor.

Timing of the movements of the gripper and lug belt conveyors 22 and 32 to insure that the articles are properly gripped by assemblies 34 is accomplished by employing a single drive system 84 (see Fig. 8) for both conveyors. Adjustment of that timing to accommodate articles with different cut-off lengths is effected by shifting the drive sprocket 72 at the lower end of the lug belt conveyor.

Referring now to Figs. 1-5, the gripper assemblies 34 of conveyor 22 are mounted on, and conveyed along, conveyor track 86 by truck assemblies 88 to which the gripper assemblies may be attached by screws or the like. The track has a C-section as shown in Figures 3 and 5. The lower end of the track, extending vertically to a level such as that identified by reference characters E in Fig. 1, will typically be machined from appropriate stock for rigidity and strength and to otherwise accommodate the forces imposed upon that section of the conveyor track. Elsewhere, loads are lighter and the requirements for rigidity and strength lower. A more cost effective, rolled or otherwise formed shape will preferably be employed in those sections of the track.

As best shown in Fig. 5, each of the truck assemblies 88 has a frame 89 fabricated from a more-or-less V-shaped member 90, a W-shaped member 91, and angle-type stiffeners 92 and 94, all fixed into a unitary structure.

The lower angle 94 also serves as a mounting platform or bracket for the associated gripper assembly 34.

Supported from the frame 89 of each truck assembly 88 by axles 95 are four track-engaging wheels 96. As is apparent from Fig. 5, these wheels 96 guide the truck assembly along a path determined by the configuration and orientation of the gripper conveyor track.

The gripper assemblies 34 are best shown in Figures 3 and 3A. Each includes a sheet metal frame 104 fixed to the associated truck assembly 88. Also, each gripper assembly includes a sheet metal jaw 106 bolted or otherwise fixed to frame 104 and a shaft 108 extending transversely of the gripper assembly and supported for rotation about an axis 110 from the side walls 112 (only one of which is shown) of gripper assembly frame 104. A movable jaw 114 is fixed to shaft 108 for rotation therewith between an open position and any one of an essentially infinite number of closed positions with respect to fixed jaw 106. The open position is shown in solid lines in Fig. 3A and the "most closed" position in dotted lines in that Figure.

Like frame 104, fixed and movable jaws 106 and 114 may be made of sheet metal. The material from which the latter is fabricated will preferably be of a relatively lighter gauge, giving it sufficient flexibility to accommodate variations in the nominal thickness of the articles being handled without damage to the gripper assembly components.

Rubber, or similar, members 115 are fixed to the opposit sides of movable jaw 114. These protect the articles being handled by the gripper assemblies against damage. They also increase the friσtional forces exerted on those articles, further insuring that they will not be dropped as they are carried along the route determined by the configuration of gripper conveyor track 86.

Referring now to Figs. 3, 3A, and 5, gripper conveyor 22 includes a series of truck and gripper assembly combination connected into an endless, articulated chain by drive pins 120. The number of truck and gripper assembly combinations will vary from installation-to-installation but will be of a number such that the endless chain of assemblies is equal in length with gripper conveyor track 86.

Each drive pin 120 extends through and is supported from the frame 89 of a truck assembly 88 to which reinforcements 12 and 124 are attached. The pin is fixed through a bifurcated extension 126 of the frame of the truck assembly it follows along the gripper conveyor track (see,, particularly Fig. 3) by a frictional spring retainer 128.

The chain or train of articulated truck assemblies and gripper assemblies carried by the latter are displaced along the gripper conveyor track by the linear drive system 84 mentioned briefly above.

This drive system is shown schematically in Fig. 2 and in more detail in Figs. 8 and 9. It includes two drive motors 132 and 13" . These are supported from the conveyor system framework 46 at a location somewhat above the bottom end of the first vertical run of gripper conveyor 22 as shown in Fig. 2.

Motors 132 and 134 are connected through gear boxes 136 and 138 to gripper conveyor drives 140 and 142. Each of the

- m ORIGINAL latter includes a driven sprocket 144, a free wheeling sprocket 146, and an endless chain 148 trained around those sprockets. Each chain 148 supports a complement of carriers 152, each of which includes a drive roller 154. As shown in Fig. 5 cooperating pairs 154-1 and 154-2 of these rollers, respect¬ ively parts of the two drive systems 140 and 142, engage oppo¬ site, tapered ends 155 and 156 of the truck assembly connecting drive pins 120 from below to propel the truck assembly and gripper assembly carried by the latter upwardly along the vertical gripper conveyor run. As perhaps can best be appre¬ ciated from Fig. 5 this balances the loads on the truck assembly drive pin. This reduces wear on and increases the serivce life of, the truck and gripper assembly components.

It was pointed out above that the lower section of gripper conveyor track 86 is preferably fabricated from solid stock. As is shown in Fig. 5, a slot 159 is milled in this track to accommodate the rollers 154-2 of endless drive 142.

To further promote uniform loading and thereby even further minimize wear of the gripper conveyor components, a timing system 160 is incorporated in linear drive 84 to match the speeds of the two truck assembly drive systems 140 and 142. In the preferred embodiment of the invention under discussion, off-the-shelf gear boxes 136 and 138 have auxiliary shafts 162 and 164 for fans or other accessories. Timing sprockets 166 and 168 are fixed to these shafts, and a timing belt 170 is trained around them and an idler sprocket 172 which is adjust¬ able to take up slack in the belt.

In addition to the components discussed above, each of the gripper conveyor truck assembly pin drives 140 and 142 in¬ cludes a pair of vertically extending, backup members 180 and 182. These parallel the vertical runs of endless chains 148 and are employed to take up slack in the latter. Members 182, for example, are engaged by rollers 186 of the endless drive carrier components 152. They bias rollers 154-1 and 154-2 toward the truck assembly drive pin 120. engaged by those rollers in the direction indicated by arrows F in Fig. 5 to insure that a firm driving engagement is maintained between the driving rolls and the drive pin.

Members 180 similarly take up the slack in the endless chains 148 as they travel downwardly in the return path shown by arrow H, for example, in Fig. 8.

As is shown in the same Figure, the adjusting members in question are fixed at both their lower and upper ends to conveyor system framework 46 by adjusting screws 192 threaded into the latter. These allow the tension or force exerted on the endless chains to be adjusted for proper engagement with the truck assembly drive pins and to adjust the slack taken up in the chain on its return path.

For the sake of simplicity, the preferred embodiment of the invention illustrated in the drawings has above been dis¬ cussed as if only one drive pin 120 of the gripper conveyor ^: truck and gripper assembly was engaged by rollers 154-1 and 154-2 at any given time. In actual practice, a plurality of such drive pins are simultaneously displaced upwardly in the manner just discussed. Five such drive pins are always engaged over the vertical span of the linear drive 84 in a typical application of the present invention. This not only insures that the drive forces on each combination of truck and gripper assemblies is equalized but, also, that the driving loads are uniformly distributed over a number of assemblies, uniformly distributing those loads among the latter and further contri¬ buting to the extended service life of the novel conveyor systems disclosed herein.

Also, linear drives as just described can be employed at (preferably equally spaced) interval^'s along gripper track 86 to further equalize loads on that conveyor, if desired.

It was pointed out above that the gripper and lug belt conveyors 22 and 32 are driven from a single source to pre¬ cisely time the speeds of those two conveyors relative to each other and that this timing can be varied by adjustment of the lug belt conveyor drive sprocket 72. The drive system for the lug belt conveyor also includes a drive with an output . sprocket 193 and an input from the two gripper conveyor motors 132 and 134. An endless chain 194 is trained around sprockets 72 and 193 and the sprockets of an idler assembly 195. This assembly can be displaced along the framework 46 of gripper conveyor 22 to also adjust the timing between the gripper and lug belt conveyors. This is a one-time adjustment employed when the conveyor is set up to accommodate the articles of the cut-off length range specified by the user of the conveyor system. As the adjustment does not come into play in the operation of gripper conveyor 22, and as its details are not part of the present invention, this subsystem of conveyor 22 will not be described further herein.

Other, important subsystems of gripper conveyor 22 are those for closing the jaws of the gripper conveyor assmeblies upon the articles being handled by them and mechanisms for releasing these jaws to drop articles 78 onto conveyor 26 at one or more intermediate points along the track of the conveyor system.

The gripper assembly jaw closing mechanism is shown in Figure 6 and 7 and identified by reference character 196. It includes a cam 198 pivotally supported at its upstream end from the conveyor system framework 46 on a transversely ex¬ tending pivot member 200. The downstream end of the cam is articulately fixed by a pin 202 and connector 204 to the piston rod 206 of a pneumatic cylinder 208 also supported from the conveyor system framework. This arrangement permits cam 198 to be rotated about shaft 200 to vary the locus of cam surface 210 as shown in dotted and full lines in Fig. 6, for example. Also, by varying the pressure on the pneumatic fluid in cylinder 208, the force which the gripper assembly jaws are capable of exerting on an article clamped therebetween can be limited to a maximum appropriate to the thickness of the article. That is, the pressure in the cylinder can be in¬ creased to insure that thicker articles are securely seized and decreased when thinner articles are being handled to reduce the gripper force and, therefore, wear on the gripper assem¬ blies yet still insure that the thinner articles are secur¬ ely gripped.

Pivotably fixed to the downstream end of cam 198 by member 212 is a trailing link 214. The downstream end of the trailing link is articulately and adjustably connected to the upstream end of the conveyor system framework 46 by a spring biased linkage identified generally be reference character 216. It is not thought necessary to describe this connecting arrangement further herein as its details are not part of the present invention and as the adjustability of the connecting arrangement is employed only in setting up the system, not in its operation.

Referring now to Figures 3, 3A, 6, and 7, the moveable jaws 114 of the gripper assemblies are biased toward the open position shown in Figures 3 and 3A by coil springs 218 and 220 wound around shaft 108 at_, the opposite ends thereof. One end of each spring engages the moveable jaw 114 and the other similarly engages fixed jaw 106 to bias the moveable jaw away from the fixed jaw.

Jaw 114 is rotatably moved toward jaw 106 against the bias exerted by these springs to any one of the infinite number of closedpositions it is capable of assuming by cam 198 and a follower mechanism 221 incorporated in each of the grippper assemblies. This follower mechanism includes an arm 222 fixed to the gripper assembly shaft 108 for rotation therewith and a follower 224 rotatably supported at, and from, the free end of the arm. As each gripper assembly 34 moves past the cam closing mechanism, its cam follower 224 rolls along cam track 210. This results in shaft 108 and the moveable jaw 114 fixed to that shaft being rotatably displaced toward a closed position. The arc through which the moveable jaw can be pivoted and, therefore, the spacing between the moveable and fixed jaws in the closed position and the force which those jaws are consequently capable exerting on an article of given thickness is determined by the position in which cam 198 is located by pneumatic cylinder 208. This is in turn determined by the pressure across the fluid in that cylinder. For example, if cam surface 210 is displaced to the position shown in dotted lines shown in Fig. 6, the maximum extent to which the gripper assembly jaws 106 and 114 can be closed is greater than if the cam surface is in the full line position shown in that Figure. At the same time, the gripping force which those jaws are capable of exerting is limited by the pneumatic pressure in cylinder 208. If the resisting force exerted by the gripper assembly jaws on the article clamped therebetween exceeds that pressure, cam member 198 will simply retract upwardly against the force exerted by the pneumatic cylinder, limiting the rotation of movable jaw 114 to a closed position by the cam follower mechanism because the resulting relocation of cam surface 210 will limit to a smaller magnitude the rotation of cam arm 222 and consequently, the rotation of shaft 108 and the "toward a closed position rotation" of movable jaw 114.

Referring now specifically to Fig. 11, the gripper assembly movable jaw 114 is locked in the position to which it is closed in the manner just described by a one-way spring clutch 230. That clutch includes two clutch hubs 232 and 234 and a coil spring 236.

Clutch hubs 232 and 234 are journalled on gripper assem¬ bly shaft 108 in end-to-end relationship. Hub 232 is fixed against rotation relative to the gripper assembly frame 104 in any convenient manner and is rotatable relative to shaft 108. Clutch hub 234 is fixed to the gripper -assembly shaft 108 for rotation therewith by a pin 238.

Helical or coil spring 236 overlaps and surrounds the apposite sections of the two hubs. One end of this spring is fixed to hub 232, and the spring is dimensioned to tightly grip hub 234 in the absence of a force effective to relaxed or unwind that spring. In the closing operation discussed above, the cam follower mechanism rotates shaft 108 and hub 234 in a "spring unwinding" direction, allowing that shaft, hub 234, and moveable gripper assembly jaw 114 to move toward fixed jaw 106. Rotation in the opposite direction, however, is prohibited as this is the "spring tightening" direction; and any tendency toward movement in that direction conse¬ quently locks the two hubs together and to the gripper frame, preventing rotation of the moveable jaw toward the open position.

Referring again to Fig. 6, the cam follower 224 of each gripper assembly rides from cam surface 210 onto the lower, arculately configured surface 240 of trailing link 214 as the moveable gripper assembly jaw 114 reaches.the wanted closed position and cam follower 224 rides off cam surface 210. This keeps cam follower 222 from being snapped in a clockwise direction (as shown in Fig. 6) by moveable jaw opening springs 218 and 220 as might occur if the follower simply dropped off the end of cam 198. That would be undesirable both because of the loads that would be imposed upon the gripper assembly components and because this violent movement could generate forces sufficiently large to overcome the clutch force, allowin the moveable jaw to open to a degree sufficient to drop the article being conveyed .by the gripper assembly.

Shock loads on the gripper conveyor assemblies 34 are further reduced by the dampers 254 shown in Figure 10. These dampers, fabricated from rubber or another resilient material, are housed in an extension 255 of gripper assembly frame 104 and in the return or "jaw opening" path of gripper assembly moveable jaw 114. The resilient bumper^•limits the travel of the moveable jaw as it reaches its open position and, because of its resiliency, minimizes the loads which might otherwise be imposed upon the jaw at that point.

Turning now to Figures 5, 10 and 11, the mechanism for releasing clutch 230 and allowing gripper assembly moveable jaw 114 to be restored to its open position by springs 218 and 220 (see Fig. 3) , thus permitting the -article being transferred to drop from the gripper assembly includes a clutch release 246 incorporated in each gripper assembly 34 and a release actuating mechanism 248 located at each drop-off point. Two of these are illustrated in Figure 1 and identified by reference char¬ acters 250 and 252.

The clutch release includes a collar 256 journalled on the shaft 108 of the gripper assembly 34 with which it is associated for rotation thereabout. A rotor clip 258 keeps the collar from sliding along shaft 108.

The second end or tang 257 of the gripper assembly clutch spring 236 is fixed to the release collar for rotation there¬ with as shown in Fig. 11.

Rotational movement of the collar between positions in which it is effective to unwind the clutch spring and allow the gripper assembly jaws to open and a second position in which the spring is sufficiently relaxed to lock hubs 232 and 234 together and prevent the rotation of shaft 108 and the opening of jaw 114 is limited by a disc 260 journalled on gripper assembly shaft 108 adjacent the release collar and a pin 262 fixed to the release collar and extending into a circumferentially elongated slot 264 in disc 260.

Release collar 256 has an elongated, flat extension 266 (see Fig. 10) . This extension is engagable by a roller 268 of clutch release actuating mechanism 248 as the gripper assembly moves past the drop-off point at which the actuating mechanism is located. This relative movement between the release collar extension 266 and roller 268 as a gripper assembly 34 moves past the drop-off point (to the left as shown in Fig. 10) results in relaxing or unwrapping of the clutch spring allowing gripper assembly jaw 114 to be restored by springs 218 and 220 to its open position.

The elongated collar extension arrangement just described insures that the release collar will stay in its clutch spring relaxing position for a period which is sufficiently long to allow the moveable gripper assembly jaw 114 to fully restore to its open position. Referring now specifically to Figures 5 and 10, the roller 268 of the clutch release actuating assembly is carried on one end of lever 279which is supported from the conveyor system track 86 by a pivot member 272, a bracket 274, and a support 276 bolted or otherwise fixed to the track.

Lever 270 can be displaced between an operative position in which roller 268 is positioned to engage release collar extension 266 in the manner just described and (clockwise, as shown in Fig. 10) to a second position in which the roller will not engage the release collar. In that case, the clutch release mechanism is not actuated; and the gripper mechanism is located without dropping off the article clamped between its jaws.

Lever 270 can be shifted between the positions just de¬ scribed by solenoids 278 and 280 having armatures 282 and 284 fixed to lever 270 on opposite sides of pivot member 272. This permits lever 270 to be shifted between its operative and in¬ operative positions so fast that even a single gripper assembly can be opened, allowing a single article to be removed from the stream ofthose being transferred by the gripper conveyor although a larger number can of course be removed from the strea by keeping lever 270 in its operative position for a longer period of time, if desired.

This novel arrangement is particularly useful in newspaper handling and similar applications of the invention, for example, as it permits single check copies or a small number of such copies to be recovered from the stream of copies at a drop-off point such as that shown at 250 in Fig. 1.

The invention described and claimed herein may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The preferred embodiment described above is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the fore¬ going description; and all changes which come within the meanin and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. An article conveyor comprising: a gripper assembly for seizing and thereafter conveying an article delivered to the feed end of said conveyor in a specified orientation along a path determined by the configuration of said track; a truck assembly having means engageable with said track to moveably guide said truck assembly therealong and bracket means to which said gripper assembly can be attached, and means for displacing said truck assembly along said track comprising first and second spaced apart endless members having segments extending along and proximate to said track, rollers carried by and spaced at a fixed pitch along said endless members, and a truck assembly drive means simultaneously and drivingly engageable on opposite sides thereof by corresponding rollers of the endless members.

2. An article conveyor as defined in claim 1 wherein the means for displacing said truck assembly along said path also comprises rotatable drive members around which said first and second endless members are trained; a separate drive means for rotating each of said rotatable drive me bers, said drive means each having an accessory shaft; and timing means drivingly connecting the accessory shafts of the two drive means and thereby so synchronizing the rotation of said drive members as to equalize the forces exerted on the opposite sides of the truck assembly drive means engaged by the cooperating rollers of said first and second endless members .

3. An article conveyor as defined in claim 1 wherein said truck assembly displacing means also comprises back-up members for biasing the aforesaid endless members toward said truck assembly displacing means to insure drive contact between the cooperating rollers carried by said endless members and the truck assembly displacement means engaged by said rollers.

4. An article conveyor as defined in claim 3 wherein said truck assembly displacing means also includes means for shifting said back-up members toward and away from the paths of said endless members to thereby adjust the positions of the rollers carried by said endless members relative to said truck assembly drive means .

5. As article conveyor as defined in claim 1 which has a plurality of gripper and truck assembly combinations as aforesaid, successive ones of said combinations being connected for pivotable movement relative to each other by a truck assembly drive means as aforesaid.

6. An article conveyor as defined in claim 5 wherein said endless members carry plural cooperating pairs of rollers that are spaced to concurrently engage a plurality of said truck assembly drive means and thereby distribute the truck assembly displacing force among said plurality of truck assemblies, thereby promoting increased service life by reducing the load on each said truck assembly.

7. An article conveyor comprising: a track; a gripper assembly for seizing and thereafter conveying an article of parallelepipedal or generally parallelepipedal configuration in a specified orientation along a path determined by the configuration of said track, said gripper assembly comprising a first fixed jaw and a second, moveable jaw pivotally fixed to said first jaw for rotation relative thereto; means which is activatable to lock said second, moveable jaw in a closed position relative to said first jaw; and means for releasing said locking means and allowing said moveable jaw to be restored to an open position relative to said fixed jaw, said release means comprising an actuator incorporated in the gripper assembly, said actuator being displacable to an operative position which allows said moveable jaw to be restored to an open position as aforesaid and means fixed relative to said track and contactable by said actuator for displacing said actuator to an operative position as aforesaid as the gripper assembly in which said actuator is incorporated reaches a specified position along said track.

8. An article conveyor as defined in claim 7 which has a serial arrangement of gripper assemblies as aforesaid and means for moving said actuator displacing means between operative and inoperative positions, whereby the moveable jaws of only selected ones of said gripper assemblies will be opened as said gripper assemblies reach the locale of said actuator displacing means.

9. An article conveyor as defined in claim 7 wherein the means for moving the actuator displacing means between operative and inoperative positions as aforesaid comprises a first solenoid for moving said actuator to the operative position and a second solenoid for moving said actuator to the inoperative position whereby, even during high speed operation of said conveyor, the residence time of said actuator displacing means in said operative position can be so limited that only the moveable jaw of a single gripper mechanism will be opened.

10. An article conveyor as defined in claim 7 wherein there is sliding or other extended contact between said gripper assembly incorporated actuator and a component of said actuator displacing means as said gripper assembly passes said specified location along said track whereby said actuator will remain in said operative position for a sufficiently long time to insure that said locking means will be released for the time needed to restore said moveable gripper assembly jaw to its open position.

11. An article conveyor comprising: a track, a gripper assembly for seizing and thereafter conveying an article in a specified orientation along a path determined by the configuration of said track, said gripper assembly comprising a first fixed jaw; a second, moveable jaw pivotably fixed to said first jaw for rotation relative thereto; and means which is activatable to rotate said second, moveable jaw relative to said fixed jaw; means for locking said moveable jaw in the position to which it is rotated, said article conveyor system further comprising: actuator means relative to which said gripper assembly is moveable for activating said jaw relating means, said actuator means including means that can be adjusted to so effect the locking of said second jaw relative to said first jaw as to vary the maximum force which said jaws are capable of exerting on an article clamped therebetween.

12. An article conveyor as defined in claim 11 wherein the adjustable means of the actuator means comprises: cam means cooperable with said jaw rotating means to activate the latter as the gripper moves relative to and past the actuator means, means mounting said cam means for movement toward and away from the path of movement of the gripper assembly, and means which can be adjusted to exert a selectively variable resistance to the movement of said cam means and, consequentially, the maximum force exertable by said gripper assembly jaws as aforesaid.

13. An article conveyor as defined in claim 12 wherein the means providing the selectively variable resistance comprises a pneumatic cylinder.

14. An article conveyor system comprising: a track; a gripper assembly for seizing and thereafter conveying an article of parallelepipedal or generally parallelepipedal configuration in a specified orientation along a path determined by the configuration of said track, a truck assembly having bracket means to which said gripper assembly can be attached, and means for guiding said gripper assembly along said track, said gripper assembly comprising: one jaw fastened to the bracket means of said truck assembly; a second moveable jaw pivotally fixed to said first jaw for rotation relative thereto; and means which is aσtivatable to lock said moveable jaw in any one of an infinite number of closed positions relative to said fixed jaw, said last-mentioned means comprising: a cam-activated mechanism including a follower incorporated in said gripper assembly, means providing a cam path traversable by said follower, and means for so adjusting the profile of said cam path relative to said conveyor system track so as to vary the spacing that will be produced between said fixed and moveable jaws when said moveable jaw is rotatably moved toward and locked in a selected one of said positions relative to said fixed jaw.

15. A conveyor system for transferring articles of parallelepipedal or generally parallelepipedal configuration from a first location to a second location removed from said first location, said conveyor system comprising: a conveyor having serially arranged gripper assemblies for conveying said articles from a location proximate said first location to said second location; a lug belt conveyor for so transferring said articles from said first location to the feed end of said gripper conveyor as to cause the leading edge of each successive article to be seized by succeeding ones of said gripper assemblies as said articles reach the feed end of the gripper conveyor; and means for so actuating each successive gripper assembly as to cause that assembly to seize a successive one of the articles arriving at a specified location at the feed end of the gripper conveyor, said lug belt conveyor comprising an endless carrier and lugs spaced at a fixed pitch therealong, said lugs being configured and oriented to be engaged by the trailing edges of successive articles delivered to the feed end of that conveyor, said system further comprising a single means for so driving the gripper and lug belt conveyors that the leading edge of each successive article will be so positioned as to be seized by a succeeding gripper assembly when that gripper assembly is actuated, said drive means including adjustment means for varying the rate of advance of the lug belt conveyor relative to the rate of advance of- the gripper conveyor and thereby changing the time required for each lug to propel the article engaged by it to the position where that article is seized by a gripper assembly, thereby accommodating the gripper conveyor to articles which vary in length from top to bottom by changing the frequency with which said articles are delivered to said gripper assemblies .

16. A conveyor system for transferring articles having a parallelepipedal or generally parallelepipedal configuration from an infeed conveyor to a location removed from said infeed conveyor, said conveyor system comprising: a first conveyor for transferring said articles from a location proximate the discharge end of the infeed conveyor to said removed location; means comprising a second, upwardly inclined conveyor having a moveable means providing an article supporting surface for transferring said articles from said infeed conveyor to said first conveyor; an endless means for biasing said articles against said moveable means to cause said articles to move therewith from said infeed conveyor toward the first conveyor of said conveyor system; and means at the upper and lower ends of the endless biasing means for so supporting said biasing means in the aforesaid orientation that the distance between said surfaces can be changed to accommodate articles of different thicknesses, there being flexible links in said support means which allow said endless biasing means to move away from said article surface if two or more superimposed articles arrive together at said second conveyor.

17. A conveyor system for transferring articles having a parallelepipedal or generally parallelepipedal configuration from a first location to a second location, said conveyor system comprising: a gripper conveyor for conveying said articles from a location proximate said first location to a second location and a second conveyor having an upwardly inclined, moving article supporting means for transferring said articles from said first location to the infeed end of said gripper conveyor, said gripper conveyor comprising a track and a plurality of gripper assemblies which are moveable along said track at a fixed pitch, each of said gripper assemblies having a first jaw with an orientation which is fixed relative to said track, a second jaw which is pivotable from an open position toward second jaw, and means at the upstream end of the assembly for pivotally fixing said moveable jaw to said fixed jaw with an opening facing the upstream side of the assembly provided between said jaws when the moveable jaw is in the open position; said second conveyor comprising means pivotally supporting the lower, upstream end of the second conveyor for rotation about a horizontal axis and said conveyor system further comprising means supporting the upper end of said second conveyor which can be activated to so raise and lower the upper edge of said conveyor as to align the upper edges of said articles with the openings in the gripper assemblies by which they are seized as the articles approach said gripper assemblies.

18. A conveyor system for transferring articles having a parallelepipedal or generally parallelepipedal configuration from an infeed conveyor, said conveyor system comprising: a gripper conveyor for transferring said articles from a location proximate the discharge end of said infeed conveyor to said removed location, an upwardly inclined lug belt conveyor for so delivering said articles to said gripper conveyor that successive articles can be seized by successive grippers of the gripper conveyor; and means for exerting on said articles as they approach the lower end of said lug belt conveyor a driving force which is of sufficient magnitude to cause the lower edge of each said article to travel beyond and be engageable by an approaching lug of said lug belt conveyor, the means for exerting said driving force comprising a pair of endless members providing a nip in the path of and through which said articles pass as they approach the gripper conveyor and means for driving at least one of said endless members.

19. ^"A conveyor system for transferring articles of a parallelepipedal or generally parallelepipedal configuration from an infeed conveyor to a location removed therefrom, said system comprising: a gripper conveyor having serially spaced grippers assemblies for seizing articles delivered thereto from the infeed conveyor and transferring said articles along a predetermined route to said removed location, a conveyor located upstream of said gripper conveyor for so transferring articles delivered by said infeed conveyor to said gripper conveyor t h a t successive articles will be properly located at and be securely seized by successive ones of said gripper assemblies as they arrive at the infeed end of said gripper conveyor, and an emergency conveyor located between said infeed conveyor and said gripper conveyor, said emergency conveyor being shiftable from a first position in which articles arriving on said infeed conveyor travel to said gripper conveyor to a second position in which said articles are diverted away from said gripper conveyor if a malfunction occurs or if articles are delivered by said infeed conveyor at an abnormal rate to ^'thereby keep said articles from damaging said gripper conveyor.

20. An article conveyor system comprising: a track; a gripper assembly for seizing and thereafter conveying an article of a parallelepipedal or generally parallelepipedal configuration in a specified orientation along a path determined by the configuration of said track; a truck assembly having bracket means to which said gripper assembly can be attached; and means for guiding said gripper and truck assembly combination along said track, said gripper assembly comprising: one jaw fastened to the bracket means of said truck assembly, a second, moveable jaw pivotably fixed to said first jaw for rotation relative thereto; and a releasable clutch means which is activatable to lock said second moveable jaw in a closed position relative to said fixed jaw, a clutch activating mechanism including a follower incorporated in said gripper assembly and moveable between at rest and operable positions, cam means providing a path so traversable by said follower as to activate said clutch means as said follower traverses said path, and a deceleration means downstrean from said cam means onto which said follower can so ride from said cam means as to keep said follower from returning to its rest position with a force of sufficient magnitude to prematurely release said clutch. 21. A gripper assembly for an article conveyor, said assembly comprising: a fixed jaw, a moveable jaw, means fixing said moveable jaw to said fixed jaw for pivotable movement relative to the latter between an open position and any particular one of an infinite number of closed positions, means for locking said moveable jaw in said particular one of said closed positions, and release means which can thereafter be activated to free said moveable jaw for movement relative to said fixed jaw to said open position.

22. A gripper assembly as defined in claim 21 which has a frame means to which said fixed jaw is attached and from which the means fixing said moveable jaw to said fixed jaw for pivotable movement relative thereto is supported, the last-mentioned means comprising a shaft extending from side-to-side of said frame and means for fixing said moveable jaw to said shaft and the means for locking said moveable jaw in said particular one of said closed positions comprising a first clutch hub journalled on and fixed to said gripper assembly shaft for rotation therewith, a second hub journalled on and rotatable relative to the frame of said gripper assembly, a coil spring wound on and spanning opposite portions of said first and second hubs and effective to lock said hubs together and prevent rotation of the second hub relative to the first hub and, consequentially, rotation of the gripper assembly frame in a jaw opening direction.

23. A gripper assembly as defined in claim 22 which also includes a release member rotatable relative to said shaft, one end of said coil spring being fixed relative to said first hub and the other end thereof being fixed relative to said release member, whereby rotation of said release member can be utilized to relax said spring, thereby freeing said second hub for rotation relative to said first hub and allowing said shaft to rotate and pivot said moveable jaw- toward its open position.

24. A gripper assembly as defined in claim 22 which. includes means biasing said moveable jaw toward said open position.

25. A gripper assembly for an article conveyor, said assembly comprising: a fixed jaw, a moveable jaw, means fixing said moveable jaw to said fixed jaw for pivotable movement relative to the latter between open and closed positions, a spring clutch means for locking said moveable jaw in a closed position, release means which can thereafter be activated to release said clutch and free said moveable jaw for movement relative to said fixed jaw, and means operable upon the activation of said release means to restore said moveable jaw to said open position.

26. A gripper assembly as defined in claim 26 which has a frame means to which said fixed jaw is attached and from which the means pivotably fixing said moveable jaw to said fixed jaw for pivotable movement relative thereto is supported, said gripper assembly also including bumper means supported by said housing and engageable by said moveable jaw as the latter is restored to its open position to reduce the imposition of shock loads by said moveable jaw on other components of said assembly.

27. A gripper assembly as defined in claim 25 which has a frame means to which said fixed jaw is attached and from which the means pivotably fixing said moveable jaw to said fixed jaw for pivotable movement relative thereto is supported, the last-mentioned means comprising a shaft extending from side-to-side of said frame and means fixing said moveable jaw to said shaft and the means for restoring said moveable jaw to its open position comprising coil springs surrounding said shaft at opposite ends thereof, each of said coil springs having a first end portion engaging the moveable jaw of the gripper assembly and a second coil spring engaging the fixed jaw of that assembly.