US3032339A

US3032339A - Sheet stack advance mechanism

Info

Publication number: US3032339A
Application number: US772552A
Authority: US
Inventors: Ted J Misbin; Robert R Tarbuck; Solyst Eric
Original assignee: Burroughs Corp
Current assignee: Unisys Corp
Priority date: 1958-11-07
Filing date: 1958-11-07
Publication date: 1962-05-01
Anticipated expiration: 1979-05-01
Also published as: GB926247A

Description

May 1, 1962 T. J. MlSBlN ETAL SHEET STACK ADVANCE MECHANISM 6 Sheets-Sheet 1 Filed Nov. 7, 1958 S m m m w.

TED J. MISBIN ROBERT R. TARBUCK ERIK R. SOLYST ATTORNEY May 1, 1962 T. J. MISBIN ETAL SHEET STACK ADVANCE MECHANISM 6 SheetsSheet 2 Filed Nov. '7, 1958 INVENTORS TED J. MlSBlN ROBERT R. TARBUCK ERIK R. SOLYST ATTORNEY May 1, 1962 Filed Nov. 7, 1958 T. J. MlSBlN ETAL SHEET STACK ADVANCE MECHANISM 6 Sheets-Sheet 5 yl I E] BY 1 E INVENTORS TED J. MISBIN ROBERT R. TARBUCK ERIK R. SOLYST ATTORNEY May 1, 1962 T. J. MlSBlN ETAL SHEET STACK ADVANCE MECHANISM 6 Sheets-Sheet 4 Filed Nov. '7, 1958 ATTORNEY INVENTORS TED J. MISBIN ROBERT R. TARBUCK ERIK R SOLYST Ill.

May 1, 1962 Filed NOV. '7, 1958 T. J. MlSBlN ETAL SHEET STACK ADVANCE MECHANISM 6 Sheets-Sheet 5 INVENTORS TED J. MlSBlN ROBERT R. TARBUCK ERlK R. SOLYST ATTORNEY May 1, 1962 T. J. MISBIN ETAL 3,032,339

SHEET STACK ADVANCE MECHANISM 6 Sheets-Sheet 6.

Filed NOV. 7, 1958 W. R N INVENTORS E TED J. MlSBlN ROBERT R. TARBUCK ER\K R. SOLYST ATTORNFY United States Patent 3,032,339 SHEET STACK ADVANCE MECHANISM Ted J. Misbin, Bryn Mawr, Robert R. Tarbuclt, West Chester, and Eric Solyst, Havertown, Pa., assignors to Burroughs Corporation, Detroit, Mich., a corporation of Michigan Filed Nov. 7, 1958, Ser. No. 772,552 22 Claims. (Cl. 27162) This invention relates generally to improvements in machines for handling sheet material and more particularly to apparatus for advancing a stack of sheets to a delivery point where the sheets are separated from the stack. While not limited thereto, the invention finds special application in mechanized banking operations, as for example, in sorting machines for advancing stacks of checks, punched cards and the like to a feeding mechanism for individual and successive feeding from the stack.

An object of the invention is to provide a novel sheet stack advancing mechanism.

Another object of the invention is to provide a reloadable sheet stack feeding apparatus enabling an operator to replenish the stack of sheets while the machine continues in operation.

A further object of the invention is to provide an improved sheet stack advancing mechanism for more efiicient and reliable handling of stacks of intermixed sheets of various sizes.

A still further object of the present invention is to provide a sheet feeding device wherein the friction of the moving stack of sheets through the stack support is substantially eliminated whereby the sheet stack may be advanced more efficiently and with less power.

In accordance with the above objects and first considered in its broad aspects, the invention comprises a sheet feeding mechanism for handling stacks of sheets or documents, such as bank checks, of the same or of different sizes. The mechanism includes a support for the stack and means for moving the stack through the support with substantially no friction between the stack and the support. A plurality of pusher devices are selectively operable to advance the stack through the support, or hopper, to a feeding station where the sheets may be separated from the stack, and are cooperable to provide means for replenishing the stack during operation of the mechanism and while the stack is advancing toward the feeding station.

The invention will be more fully revealed in the following detailed description of a specific embodiment thereof when read in conjunction with the accompanying drawings in which:

FIG. 1 is a left side elevation of a sheet stack advancing mechanism constructed in accordance with the present invention;

FIG. 2 is a view of the apparatus of FIG. 1 taken in the direction of arrows 2--2;

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2;

FIG. 4 is a sectional view taken along line 44 of FIG. 3;

FIG. 5 is a sectional view taken along line 5-5 of FIG. 14;

FIG. 6 is a view taken in the direction of arrows 66 of FIG. 3;

FIG. 7 is a sectional view taken along line, 7-7 of FIG. 3;

FIG. 8 is a sectional view taken along line 8-8 of FIG. 3;

FIG. 9 is a sectional view taken along line 9-9 of FIG. 3 but illustrated diagrammatically in perspective;

FIG. 10 is a sectional view taken along line 10-10 of FIG. 2;

FIG. 11 is a sectional view taken along line 11--11 of FIG. 9;

FIG. 12 is a sectional view taken along line 12-12 of FIG. 2;

FIG. 13 is a sectional view taken along line 13-13 of FIG. 2;

FIG. 14 illustrates stack advancing operations and progressive steps in a stack reloading operation;

FIG. 15 (shown on the same sheet as FIG. 1) is a sectional view along line 1515 of FIG. 2;

FIG. 16 illustrates other stack advancing operations; and,

FIG. 17 (shown on the same sheet as FIG. 9) is a curve diagram of a modified current used in connection with the stack hopper vibrating apparatus.

The illustrated embodiment of the invention shown in the drawings comprises a stack hopper and stack advancing units adapted for advancing aligned as well as unaligned stacks of intermixed sheets of various sizes to a sheet feeding unit, such as an endless belt.

An aligned stack is defined as one which has been previously conditioned so that an edge of all the sheets will register against a hopper member, or side plate as it is referred to hereinafter, while an unaligned stack of sheets is one in which the sheets are randomly disposed within the stack with a number of the sheets not registered against the side plate. In the latter case, the sheets which are not registered against the side plate are hanging up in the stack creating a loose stack area, so that ordinarily. it would be ditficult to separate sheets from the stack because of the danger of their striking against the side plate and buckling when they are removed from the stack by the sheet feeding belt.

For advancing aligned stacks of sheets, multiple sheet stack advancing units or pushers are provided, each of which may operate to advance a stack of sheets and which cooperate in effecting reloading operations. While one of the stack advancing units is advancing a first stack of sheets reloading is accomplished by having a second stack advancing unit temporarily advance a second stack of sheets, and then transferring the advancing function of both units to one of the units which then continues advancing both sheet stacks as a single stack.

For advancing an unaligned stack of sheets, devices are provided in one of the stack advancing units to compensate for the loose area of the stack thus assuring the sheet stack being compressed against the feeding belt to prevent the possibility of the sheets striking against the side plate as they are being separated from the stack. Means are also provided to vibrate the hopper, for both aligned and unaligned stacks, whereby friction between the hopper and the stack of sheets is reduced to a minimum during advance of the stack to the sheet feeding station. 7

As shown in the drawings, a specific sheet stack advancing mechanism constructed in accordance with .the present invention is used for advancing a stack of sheets to a separating or feeding station at which point-the sheets are removed from the stack individually in suc cession by a sheet separating or sheet feeding unit. Such a sheet feeding unit may take the form, for example,- of an endless belt 10 (FIGS. 1 and 2) mounted on

pulleys

11 and 12, the former of which is driven by-the machine motor M. The pulleys are rotatably mounted on a fixed bracket 13 secured to a frame 14 of an associated ma-. chine such as a check sorter.

A sheet stack hopper indicated generally at 15 comprises a sheet stack support or table 16 having secured along a portion of its lower edge an upwardly extending side plate 17. As will hereinafter be explained, it is preferable to impart to table 16 a vibratory motion and for such purpose table 16 is formed with depending flange portions 18 (FIG. 12) by means of which the table is secured to shock mountings 19 fixed in suitable bearing blocks secured to frame 14. The shock mounting shown in FIG. 12 comprises a rigid outer shell 20, a rigid bushing21 and resilient material 22, such as rubber. Table 16 is vibrated by means of a magnetic bar or armature 23 (FIG. 2) secured to an upwardly extending flange 24 on table 16 and adjacent an electromagnet 25 fixed to a bracket 26 (FIG. 1) secured to frame 14.

Below table 16 are two parallel ways or guide shafts 27 and 28 (FIG. 6) which are secured at their ends in suitable brackets inframe 14.

Shafts

27 and 28 support and guide two stack pusher means F and R (FIG. 2), which are designated forward and rearward respectively with regard to the direction of stack advance. The forward and rearward pusher means, F and R, are seen in FIG. 2 in left and right positions respectively, while their carriage mechanisms, as will appear more fully hereinafter, are seen in FIG. 6 in the reverse order, that is, right and left.

The rearward pusher means R comprises a carriage 29 (FIG. 6) formed with a bore by means of which it is mounted for sliding movement on shaft 27 and fitted with two rollers 30 which embrace shaft 28 at diametrically opposite places and which are mounted on pins 31 secured to carriage 29. Rollers 30-serve to maintain carriage 29 against rocking motion on shaft 27. Carriage 29 is formed with two body extensions32 and 33 which support respectively an idler sprocket wheel 34 and a drive sprocket wheel'35. As seen in FIG. 11, sprocket wheel 34 is secured toa shouldered bushing 36 mounted on anti-friction bearings 37 and adapted for rotation on a stub shaft 38secured to extension 32. Drive sprocket wheel is secured to a sleeve 39 mounted on antifriction bearings 40 and adapted for rotation on a stub shaft 41 secured to extension 33. A flanged sleeve 42 is provided with a counterbore at each end by means of which it is mounted for rocking motion on sleeve 39 and a flange 43 of shaft 41. A right-hand helical spring clutch 44 is normally tightly wound about diameter portions 45 and 46 of shaft 41 and sleeve 39 with one of its ends secured in a locking hole in shoulder 43 and the other end secured in a locking hole in sleeve 42. Secured to the flange of sleeve 42 is a collar 47 formed with a depending finger 48.

- Pivotally mounted on a pin 49 secured to carriage 29 (FIG. 6) is a three-armed bell-crank lever 50 (see also 7 FIG. 3) having one of its arms 51 normally in position foroperating on finger 48 and an arm 52 with a bent ear portion53 to which is secured one end of a tension spring 54, the other end of which is secured to a post 55 secured to carriage 29. A third arm 56 of lever 50 is formed With'a' cam surface 57 for latching the pusher mechanism in retracted position as will be explained more fully hereinafter.

Also pivotally mounted on pin 49 between lever 50 andcarriage 29 is a second three-armed bell-crank lever 58, shown also in phantom at 59 in a moved position, having onearm 60 normally disposed behind arm 51 and also being in position to operate on finger 48. A second arm 61 of lever 58 has secured to its end at 62 a'cable 63 which passes around pulleys 64 and 65 mounted on a bracket 66 secured to carriage 29 and leads to a control device for engaging and disengaging the. carriage drive in a manner to be explained. A tension spring 67 having one of its ends secured to a third arm 68 of lever 58 and the other-of its ends secured to a fixed post 69 on carriage 29 serves to bias lever 58 to its-normal'position shown in solid lines.

As seen in FIG. 3, the stack advancing portion of the rearward pusher means R comprises a casing 70 supported at a spaced distance from table 16 and side plate 17 by means of an angle bracket 71 whose lateral leg 72 is secured to frame members 73 and 74 of casing 70 and whose depending leg 75 is secured to carriage 20. Cable 63 passes over a pulley 76 mounted on a bracket 77 secured to bracket 71 and then through a suitable aperture in casing 70 to the interior thereof at which place its upper end portion is secured to a bell-crank lever 78 FIG. 7) pivotally mounted on a fixed pin 79. A control device, or de-clutching button 80 (FIG. 4), is pivotally mounted on a pin 81' fixed to casing 70 and'has a depending arm 82 for engaging a lateral pin 83 secured to a slide plate 84 having an elongated slot 85 and slidably received thereby on

pins

86 and 87 secured to frame member 74. Slide 84 has a lug 88 which engages in a bifurcated arm 89 on lever 78. At this point it will now be seen that by pressing button 80 to the phanton position shown in FIG. 4, lever 78 will be rocked counterclockwise as viewed in FIG. 7, and by means of cable 63, bellcrank lever 58 and finger 48, spring clutch 44 will be given an unwrapping motion thereby to free sleeve 39 (FIG. 11) and drive sprocket wheel 35 for rotation on shaft 41.

A plunger 90 (FIG. 7) is slidably received in a bore 91 extending through a fixed block 92 secured'to casing 70. Block 92 is formed with an elongated slot 93 communicating with bore 91 and having disposed in said slot for sliding movement therealong a guide key 94 secured to one end of plunger 90. A key lever 95 (FIG. 8) is pivoted at 96 to block 92 and has an arm 97 which is normally in abutting relation with guide key 94. An arm 98 of lever 95 extends through an elongated aperture 99 in casing 70 and has secured to its outer end portion a key 100 (FIG. 3). A tension spring 101, having over-center operation, with one of its ends secured to a pin 102 on arm 98 and the other of its ends secured to 'a' fixed pin 103 serves to bias key lever 95 to either of its extreme positions at which positions wedge of aperture 99 serves as a stop for arm 98. A tension spring 104 having one end secured on a fixed pin 105 (FIG. 7) passes around pulleys 106, 107, 108' and109-and has its other end attached to guide key 94. Spring 104 is thus biasing plunger. 90 outwardly of block 92 with a constant force to an extended position, as shown in phantom in FIG. 7, but is held against so doing by the blocking action of key lever arm 97 on guide key 94.

Casing 70 is formed at its stack advancing region with a substantially rectangular front side member 110' (FIG. 7) spaced from'a casing framemember 111 and forming with member 111 an open pocket 1'12 communicating with the exterior of casing 70 (see also FIG. 5). Adjacent to one end of pocket 112, frame member 111 and side member 110 are secured together by a spacer 113 which serves also as a stop for a purpose later to be described. A portion of the upper margin of side member 110 is angularly bent at'114 (FIG. 5') to form a slide bearing for a substantially rectangular flexible stack compressing plate 115 normally in butting relation with side member 110 and having an extended portion 116 along its upper margin loosely folded about theangular margin 1140f side member 110 for sliding movement thereon.

One end of compressing plate 115 is formed at its corner regions with laterally bent ears 117 pivotally secured to lugs 118 of a stop flange 119 secured to plunger 90.

It will now be apparent that by manually pressing key 100 to rockkey lever 95 on pivot 96. in a counterclock .wise direction, as seen in FIG. 8, guide key 94 will be released from the blocking action .of arm 97 to the biasing action of spring 104 to' move plunger 90 and plate 115v to the extended position, shown in phantom in FIG 7, until guide key 94 comes against a stop face 120.0n block 92, thus. conditioning the rearward pusher fora. purpose to be described hereinafter.

A spring leaf 120a (FIGS. 1 and 7) secured to casing 70 at 12012 is normally closely adjacent'to or preferably abutting compressing plate 115 and cooperates with other parts yet to be described in performing sheet stack reloading operations. Spring leaf 120a is so placed on rearward pusherR'as' to engage the shorter sheets of the stack as well as the longer ones, regardless of the disposition of the shorter sheets in the stack.

The forward stack pusher means F comprises a carriage 1121 (FIG. 6) mounted for sliding movement on shaft 27 in a manner similar to that described for carriage 29 and also similarly guided against rocking motion on shaft 27 by means of diametrically opposite rollers 122 embracing shaft 28. Carriage 121 has extended

body portions

123 and 124 which support respectively an idler sprocket wheel 125 and a drive sprocket wheel 126. These sprocket wheels are supported in a manner similar to that described for

sprocket wheels

34 and 35, and drive sprocket wheel 126 has a spring clutch 44', not shown, similar to spring clutch 44 (FIG. 11) for drive sprocket wheel 35, and therefore no further description is deemed necessary. A bell-crank lever 127 is pivotally mounted on a pin 128 s..- cured to carriage 121 and has an arm 129 for operating on a depending finger 130 and an arm 131 to which is secured a spring post 132 in abutting relation with one end 133 of a slide plate 134. Finger 130 is similar to finger 48 and performs the same function on its respective spring clutch. Slide plate '134 is formed with two

elongated slots

135 and 136 and is mounted thereby for sliding movement on fixed

pins

137 and 138 secured to carriage 121 and supported on the pins by

washers

139 and 140 and spring locking rings 141 and 142 snapped into suitable grooves in the pins. A tension spring 143 having one of its ends attached to post 132 and the other of its ends attached to fixed pin 138 biases bell-crank lever 127 counterclockwise on pin 128 and slide plate 134 toward the position 134a shown in phantom.

Secured to carriage 121 is an upwardly extending bracket 144 (FIG. 13) to which is pivotally mounted at 145 a flag-like pusher element 146 formed with a knife edge 147, a V-notch at 148, a laterally extending L-shaped handle portion 151 (see also FIG. 2) and a cam lug 152 depending from the short leg of handle 151. As seen in FIG. 13, flag 146 is shown in solid lines in operating or stack advancing position with its notch 148 in position to clear spring leaf 120a for a purpose later to be described.

A lever 153 is pivotally mounted at 154 to bracket 144 and has at one of its ends a follower roller 155 (see also FIG. 15) bearing against cam lug 152 and at the other of its ends a laterally extending pin 156 fixed thereto and engaged in a slot 157 of a depending flange 158 of slide plate 134 (see also FIG. 6).

At this point it will be seen that if flag 146 is rocked upwardly about the pivot at 145 (FIG. 13) to a position shown at 159, the biasing action of spring 143 will cause roller 155 to follow cam lug 152 allowing lever 153 to rock counterclockwise on pivot 154 and-slide plate 134 to move to the phantom position shown in FIG. 6, whereby the following action of post 132 on the end 133 of slide plate 134 will cause bell-crank lever 127 to rock counterclockwise on pivot 128 as viewed in FIG. 6, and its arm 129 to rock finger 130 thereby to unwrap spring clutch 44' of drive sprocket 126 and free the sprocket for rotation on its stub shaft.

The forward or flag pusher carriage 121 is in driven relation with an endless transmission chain 160 (FIGS. 6 and 9) which engages drive sprocket wheel 126 and idler sprocket wheel 125 and engages about

sprocket wheels

162 and 163 rotatably mounted on a fixed bracket 163a (FIG. 2) and a sprocket wheel 164 secured on shaft 165 rotatably mounted in fixed brackets 169 and 170 (FIG. In a similar manner, the rearward pusher carriage 29 is in driven relation with an endless transmission chain 161 which engages drive sprocket wheel 35 and idler sprocket-wheel 34 and engages about sprocket wheels 166 and 167 similarly mounted as

wheels

162 and 163 and then engages around sprocket wheel 168 secured to shaft.165. When shaft 165 is rotated counterclockwise as viewed in FIG. 9, carriages 29 and 121 will be moved synchronously leftwardly in the direction of stack advance if their

respective spring clutches

44 and 44 are engaged.

The chains 1 60 and 161 operate similarly for both carriages so a description of the operation of chain 161 will sufiice. Accordingly, when spring clutch 44 is engaged, drive sprocket wheel35 will be stationary on stub shaft 41 so that carriage 29 will move leftwardly with chain 161 as depicted in phantom at 171 (FIG. 9). Since sprocket wheel 35 is not rotating on its stub shaft in such cases, sprocket wheel 34 also is stationary on its stub shaft 38. When spring clutch 44 is disengaged by rocking either of the levers 50 or 58 (FIG. 6) drive sprocket wheel 35 and also sprocket wheel 34 will then rotate freely on their respective stub shafts while chain 1611 continues driving, but carriage 29 will stop or remain stationary. In such case, it is understood that carriage 29 will be free to be moved manually along

guide shafts

27 and 28.

The drive for the chains and 161 comprises a belt 172 (FIGS. 2 and 10) coupled to motor M, and a pulley 173 secured on a drive shaft 17-4 rotatably mounted in brackets 169 and 170. A magnetic clutch device is mounted on shaft 174- and comprises a circular permanent magnet 175 secured to shaft 174 and a circular armature 176 rotatably mounted on said shaft and preferably spaced somewhat from magnet 175. Armature 176 has a reduced diameter portion formed with gear teeth 177 which is in mesh with a gear 178 secured to shaft 165. It can now be seen that by rotating drive shaft 174 in the direction of the arrow, magnet 175 will yieldably rotate armature 176 and through the medium of gear 178 and sprocket wheels 164 and 168 rotate the

transmission chains

160 and 161 to drive the forward and rearward stack pusher carriages '29 and 121 in the direction of the stack advance toward the sheet feeding belt 10.

The operation will be described first for advancing an aligned stack of sheets to the feeding belt and reloading of the hopper with additional aligned stacks while the machine is in operation, and then for advancing stacks of unaligned sheets to the feeding belt. For advancing either type of stack, that is, aligned or unaligned, it is preferable as mentioned earlier, to vibrate the hopper whereby friction between the sheet stack and the hopper table is substantially eliminated so that the force applied for advancing the stack will be substantially the same as the force with which the stack bears against the feeding belt. One way of accomplishing such vibration is by supplying an alternating current A.C. to the coil of electromagnet 25 (FIG. 1) by means of

leads

184 and 185 and placing a half-wave rectifier 186 in circuit with the coil to cut off half of the current cycle as seen in FIG. 17. Thus it will be seen that the hopper table 16, and side plate 17 secured thereto, will snap back on each return stroke under the resilient action of shock mountings 19. Satisfactory results have been obtained by so adjusting the strength of the alternating current as to produce a total stroke of the hopper of approximately .020.

In operation, button 80 is depressed manually to rock bell-crank lever 58 to declutch spring clutch 44 and the rearward pusher is then moved to its retracted position, as shown in view d, FIG. 14, while button 81) is held depressed. Movement of the pusher to this position causes cam surface 57 of bell-crank lever 50 to ride over catch 187 (FIG. 2) until a shoulder 57a at the end of cam surface 57 snaps over catch 187 to latch the pusher at this position. Bell-crank lever 50 has thus been rocked and is now in position to hold spring clutch 44 disengaged in dependently of bell-crank lever 58 so that button 80' may now be released and the pusher now held in a declutched condition in its retracted position.

With the rearward pusher in the retracted position, flag 146 of the forward pusher is lowered to its operating position shown in solid lines in FIG. =13 with spring clutch 44 engaged, and the forward pusher then moved manual- 7 1y alongrguide

shafts

27 and 28 at a faster rate than the linear velocity of

chains

160 and 161 until it engages an aligned sheet stack S, as seen in view 0, FIG. 14, at which point it will commence advancing the stack to the sheet feeding belt 10 in response to the driving action of its chain 160. It is understood that either of the pushers may be slid manually toward the feeding belt while the chains are driving even though their respective spring clutches may be engaged, since the faster motion in that direction serves to override the spring clutches. It is also apparent that if sheet feeding belt 10 were not rotating so that the stack would remain stationary, permanent magnet 175 would continue rotating with drive shaft 174 but armature 176 would be stationary relative to the drive shaft, however, when the sheet feeding belt is rotating and sheets are being removed thereby from the stack, magnet 175 will continuously urge armature 176 into rotation, so that there is here provided a yielding drive for advancing the sheet stack.

When the stack has been diminished to a convenient predetermined size, the operator then reloads the hopper while the forward pusher is still advancing stack S to the feeding belt by placing a second aligned stack S" of sheets behind the forward pusher and in tandem with stack S as seen in view a. The rearward pusher is then moved manually away from catch 187, enabling its spring clutch 44 to reengage, and pushed up against the second stack S" as seen in view 2, at which point it will commence advancing the second stack-simultaneously with advancement of the first stack by the forward pusher. Flag 146 is at this point rocked manually upwardly from between the two stacks to a position such as is shown at 159 in FIG. 13, in which position its spring clutch 44' is disengaged, and the forward pusher then slid back toward the rearward pusher until the flag knife edge 147 is. adjacent to spring leaf 120a. Flag 146 is then rocked manually downwardly until knife edge 147 passes between spring leaf 126a and compressing plate 115 as seen in view 1, until the flag is again in its lower operating position where it is now behind stack S" and with its spring clutch '44 again engaged. Button 80 is then pressed to release spring clutch 44 whereby the rearward pusher may then be slid back away from the stack and again latched in its retracted position, as seen in view d, while the forward pusher continues advancing both stacks as a unitary stack.

For advancing an unaligned stack of sheets S, shown in FIG. 16, the forward pusher is not used and is placed in an inoperative position by coupling it to the rearward pusher as seen in view a. This is accomplished by raising flag 146 to disengage spring clutch 44 and the forward pusher moved back to the rearward pusher. Flag 146 is then lowered into pocket 112 of the rearward pusher until it comes against spacer stop 113 (FIG. 13) in which position spring clutch 44 is still disengaged and the forward pusher is merely carried along by the rearward pusher.

The rearward pusher is then conditioned for the unalignedstack of sheets S by pressing key 100 (FIG. 3) to release compressing plate 115 outwardly of the rearward pusher as seen in view b, of FIG. 16, thereby to compress the stack at its'loose lower region against the feeding belt. Thus it is assured that the leading or end sheet of the stackwill be presented. along its length to the effective feeding portion of the sheet feeding belt with the desired degree of firmness, and also eliminating the possibility of having the sheets strike and buckle against side plate 17 as they are being separated from the stack.

After a stack advancing run has been completed, the machine is automatically shut off by means of a normally closed switch 138 (FIG. 2) in circuit with motor M by means of-leads 188a and 18% and having an arm 189 normally biased against the sheet stack. When the last sheet ofthe stack has been removed by the sheet feeding belt, arm 189 will spring into a suitable aperture in the particular pusher being used to open the circuit and thus shut off the machine. For such purpose, flag 146 is provided with an aperture 180 (FIG. 13) for admitting arm 189. Aperture 136 is faired or bevelled at 180a to allow for smooth declutching of the forward pusher without jolting arm 189 when the pusher is withdrawn fromshutoff to loading position. Compressing plate 115 and side member of the rearward pusher are likewise provided with suitable apertures, not shown.

In order to alert the operator at reloading time, there is provided an audible signalling device 181 (FIG. 2) in circuit with a normally open switch 182 by means of leads 182a and 182b, the switch being secured to side plate 17 and having an arm 183 disposed in the path of movement of bracket 144 of the forward pusher. Arm 183 is therefore actuated by the movement of the forward pusher to close the circuit to the signal device 181 and thereby warn the operator that the sheet stack has been diminished and that the machine requires attention. As shown in FIG. 2, the forward pusher has already actuated arm 183 and the signal has already been given.

From the foregoingdescription, it will now be apparent that the invention provides novel improvements in sheet stack advancing mechanism whereby an operator may replenish the supply of sheets while the machine continues in operation. It will-also be seen that the invention provides further improvements in such mechanisms in its capacity for handling aligned as well as unaligned stacks of sheets, and in its provision for increased operating eificiency by substantially eliminating the friction forces between the sheet stack and hopper whereby the sheet stack will bear againstthe sheet feeding medium with a predetermined amount of force, regardless of sheet stack size, the predetermined drive force being supplied by the yielding clutch drive.

While there has been described a specific sheet stack advancing mechanism constructed in accordance with the present invention, it is to be understood that this is a preferred embodiment and that the invention may be constructed in various forms without departingfrom the true spirit and scope thereof.

Accordingly, it is to be understood that the invention is not to be limited by the specific construction disclosed herein but only by the subjoined claims.

What is claimed is:

1. In a sheet feeding machine, the combination comprising, a support for a supply of sheets, means to vibrate said support, a forward stack pusher for advancing a stack ofsheets along said support, a rearward stack pusher for advancing a second stack of sheets along said support and being; reciprocaoly retractable to a sheet stack loading position, said stacks being arranged in tandem, and yieldable means to drive said pushers synchronously for advancing'said stacks.

2. The combination with an endless sheet feeding belt comprising, a sheet stack support arranged adjacent to said belt, a stack pusher for advancing a stack of sheets along said support to said feeding belt, settable means for selectively conditioning said pusher to substantially conform its stack engaging portion to the condition of a sheet stack of uniform thickness or to a stack having areas of different thickness in such manner-that a lead,- ing portion of successive sheets of the respective stacks will be pressed into contact with said sheet feeding belt, and means todrive said pusher foradvancing the particular. stack.

3. The combination with anendless sheet feeding belt comprising, a sheet stack support arranged adjacent to said belt, a stack pusher for advancinga stack of sheets along said support to said feeding belt, settable means for selectively conditioning said pusher to susbtantially conform its stack engaging portion to the condition of a sheet stack of uniform thickness or toa stack having areas of different thickness in such manner that a leading portion of successive sheets of the respective stacks will be pressed into contact with said sheet feeding belt, drive means, transmission means coupled to the drive means, clutch means engaging said pusher with the transmission means, manually operable means for declutching said clutch means, and latch means to hold the clutch means declutched when said manually operable means is released.

4. A sheet stack advancing mechanism comprising, a sheet stack support, a stack pusher having a element movable between extended and retracted positions and operable to advance a stack of sheets along said support when in said extended position, drive means, means coupling the drive means to the stack pusher when said element is in its extended position, and means actuated by movement of said element to its retracted position for uncoupling the drive means from said stack pusher.

5. A sheet stack advancing mechanism according to claim 4 wherein said drive means includes a yieldable magnetic clutch.

6. In a sheet feeding machine, the combination comprising, a sheet stack support, pusher means for advancing a stack of sheets along said support and including a pusher element movable between operating and retracted positions, drive means for said pusher means, said drive means including transmission means moving along the line of stack advance when the drive means is operating, a rotatable member mounted on the pusher means and being in driven engagement with the transmission means, means to lock said member against rotation for movement of said pusher means by said transmission means, and operable means to simultaneously release said member for rotation and remove said pusher element from operating to retracted position.

7. A combination as defined in claim 6 wherein said transmission means comprises an endless chain and said rotatable member is a sprocket wheel in mesh with said chain.

8. A combination as defined in claim 6 wherein said means to lock said member against rotation comprises a spring clutch.

9. A sheet stack advancing mechanism comprising, a stack support, pusher means for advancing a stack of sheets along said support, settable means for selectively conditioning said pusher means to substantially conform its stack engaging portion to the condition of a sheet stack of uniform thickness or a stack having areas of different thickness, drive means for said pusher means, said drive means including transmission means moving along the line of stack advance when the drive means is operating, a rotatable member mounted on the pusher means and being in driven engagement with the transmission means, means to lock said member against rotation, and operable means to release said member for rotation.

10. In combination with an endless sheet feeding belt, the mechanism comprising, a sheet stack support ar ranged adjacent to said belt, pusher means for advancing a stack of sheets along said support to said belt, said pusher means including a flexible stack compressing member and settable means to selectively condition said member for engaging a sheet stack of uniform thickness or a sheet stack having areas of different thickness in such manner that a leading portion of successive sheets of the respective stacks will be pressed into contact with said sheet feeding belt, and drive means for said pusher means.

11. In combination with an endless sheet feeding belt. the mechanism comprising, a sheet stack support arranged adjacent to said belt, means to vibrate said support, pusher means for advancing a stack of sheets along said support to said belt, said pusher means including a stack compressing member and settable means to selectively condition said member for engaging a sheet stack of uni form thickness or a sheet stack having areas of different thickness in such manner that a leading portion of successive sheets of the respective stacks will be pressed into contact with said sheet feeding belt, and yieldable drive means for said pusher means.

12. Apparatus for advancing a stack of sheets to a sheet feeding means comprising, a sheet stack support arranged adjacent to said sheet feeding means, means to vibrate said support, pusher means for advancing a stack of sheets along said support to said sheet feeding means, said pusher means including a flexible stack compressing member and settable means to selectively condition said member for engaging a sheet stack of uniform thickness or a sheet stack having areas of different thickness, yieldable drive means for said pusher means, and an endless chain coupling the pusher means to the drive means.

13. In a sheet feeding machine, the combination comprising, a sheet stack support, pusher means for advancing a stack of sheets along said support, said pusher means including a stack compressing member and settable means to selectively condition said member for engaging a sheet stack of uniform thickness or a sheet stack having areas of different thickness, drive means for said pusher means, an endless chain coupled to said drive means, and releasable clutch means engaging the pusher means with said chain.

14. In a sheet feeding machine, the combination comprising, a support for a stack of sheets, electromagnetic means to vibrate said support, pusher means for advancing a stack of sheets along said support, said pusher means including a flexible sheet stack compressing member and settable means to selectively condition said member for engaging a sheet stack of uniform thickness or a sheet stack having areas of different thickness, drive means for said pusher means, said drive means including a yieldable magnetic clutch, an endless chain coupled to said drive means, and manually releasable clutch means engaging the pusher means with said chain.

15. Apparatus for advancing a supply of sheets comprising a hopper, a forward sheet stack pusher having a member movable between extended and retracted positions and operable to advance a first stack of sheets along said hopper when in said extended position, said member being adapted for engaging a part of the area of said stack, a rearward stack pusher for advancing a second stack of sheets along said hopper in tandem with said first stack and including an element adapted for engaging a part of the area of said second stack, said latter area being displaced relative to said first-mentioned area, said element being moveable relative to said rearward pusher to accommodate the passage therebetween of said member when the latter is moved from retracted to extended position, drive means for said pushers, transmission means coupled to the drive means, and manually releasable clutch means engaging said pushers with the transmission means.

16. Apparatus for advancing a supply of sheets comprising, a hopper, aforward sheet stack pusher having a member movable between extended and retracted positions and operable to advance a first stack of sheets along said hopper when in said extended position, said member being adapted for engaging a part of the area of said stack, a rearward stack pusher for advancing a second stack of sheets along said hopper in tandem with said first stack and including an element adapted for engaging -a part of the area of said second stack, said latter area being displaced relative to said first-mentioned area, said element being movable relative to said rearward pusher to accommodate the passage therebetween of said member when the latter is moved from retracted to extended position, drive means for said pushers, transmission means coupled to the drive means, individual clutch means for each of said pushers engaging the same with the transmission means, manually operable means for declutching the clutch means of the rearward pusher, and latch means to hold the clutch means of the rearward pusher declutched when said manually operable means is released.

17. In combination with an endless sheet feeding belt,

aoaaaaa the apparatus comprising, a stack hopper, electromag netic means to vibrate said hopper, a forward stack pusher having a member movable between extended and retracted positions and operable to advance a first stack of sheets along said hopper when in said extended position, said member being adapted for engaging a part of the area of said stack, a rearward stack pusher for advancing a second stack of sheets along said hopper in tandem with said first stack and including an element adapted for engaging a part of the area of said second stack, said latter area being displaced relative to said first-mentioned area, said element being movable relative to said rearward pusher to accommodate the passage therebetween of said member when the latter is moved from retracted to extended position, drive means for said pushers including a yieldable magnetic clutch, endless chains coupled to the drive means, a rotatable sprocket wheel mounted on each of said pushers and each sprocket wheel being in driven engagement with one of said chains, spring clutch means carried by each of said pushers for locking their respective sprocket wheels against rotation, manually operable means to release the spring clutch means of the rearward pusher to free its sprocket wheel for rotation, and manually operable means to simultaneously release the spring clutch means of the forward pusher to free its sprocket wheel for rotation and to remove said member from exended to retracted position.

18. In combination with an endless sheet feeding belt, the apparatus comprising, a stack hopper, means to vibrate said hopper, a forward stackpusher having a member movable between extended and retracted positions and operable to advance a first aligned stack of sheets along said hopper when in said extended position, said member being adapted for engaging a part of the area of said stack, a rearward stack pusher for advancing a second aligned stack of sheets along said hopper in tandem with said first stack and including an element adapted for engaging a part of the area of said second stack, said latter area being displaced relative to said first-mentioned area, said element being movable relative to said rearward pusher to accommodate the passage therebetween of said member when the latter is moved from retracted to extended position, said rearward pusher including settable means for selectively conditioning the same for advancing aligned stacks of sheets or unaligned stacks of sheets, said rearward pusher being operable independently of said forward pusher for advancing unaligned stacks of sheets, yieldable drive means, endless chains coupled to the drive means, a rotatable sprocket wheel mounted on each of said pushers and each sprocket wheel being in driven engagement with one of said chains, clutch means carried by each of said pushers for locking their respective sprocket wheels against rotation, manually operable means to release the clutch means of the rearward pusher to free its sprocket wheel for rotation, and manually operable means to simultaneously release the clutch means of the forward pusher to free its sprocket wheel for rotaill tion and to remove said member from extended to retracted position.

19. A sheet stack advancing mechanism comprising, a sheet stack support, first and second means arranged in tandem for advancing first and second stacks of sheets respectively in a forward direction toward a sheet separation station, said second stack advancing means being rearwardly of said first stack advancing means, said first stack advancing means including a thin blade-like stack pushing element engageable with the rearward end of said first stack of sheets and in the path of movement of said second stack of sheets and said second stack advancing means when so engaged, said stack pushing element being mounted for pivotal movement away from its stack pushing position to permit said second stack advancing means to urge said second stack against said first stack to combine said first and second stacks, power driving means coupled to each said stack advancing means, and means actuated by said movement of said stack pushing element for uncoupling said first stack advancing means from the driving means.

20. A construction in accordance with claim 19 wherein said second stack advancing means includes a member for guiding said blade-like pushing element between said second stack advancing means and the sheet in contact therewith, whereby the stack advancing function of said second stack advancing means is transferred to said first stack advancing means.

21. A construction according to claim 20 and further including means for releasing said second stack advancing means from said drive means during advancement of said combined stack of sheets by said first stack advancing means.

22. Apparatus in accordance with claim 20 and further including means for combining said stack advancing means as a unit when said first stack advancing r;neans is uncoupled from the driving means. i

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