US2609111A

US2609111A - Box stacking mechanism

Info

Publication number: US2609111A
Application number: US711524A
Authority: US
Inventors: Bruner R Daves; Warren L Irvine
Original assignee: Individual
Current assignee: Individual
Priority date: 1946-11-22
Filing date: 1946-11-22
Publication date: 1952-09-02
Anticipated expiration: 1969-09-02

Description

2,609,l l l Sept. 2, 1952 B. n. DAVES ETAL Box SMOKING MECHANISM 4 Sheets-Sheet" 1 Filed Nov. 22,. 1946 Bnnentors.

Bu @MW (Ittorneg Sept. 2, 1952 B. R. DAvEs ETAL Box STACKING MEcHANisM 4 Sheets-Sheet 2 Filed NOV. 22, 1946 nventors,

attorney SePt- 2, 1952 B. R. DAvl-:s ETAL 2,609,111

' Box sTAcxrNG MECHANISM Filed Nov. 22, 1946 4 Sheets-Sheet I5 Srwentors.

Gttorneg Sept. 2, 1952 B. R. DAvEs Erl-Al.v 2,609,111

Box sTAcxING MEcHANIsM Filed Nov. 22, 1946 Sil/Mete i. @A1/5, l Miei/VL'ZIQV/Ms; J5 J5 nventors.

Gttomeg Patented Sept. 2, 1952 Bruner R; Davos and Warren L. Irvine,vv d Claremont, Gali. A

Application November 22., 1946, Serial No. '711,524V

This invention relates vto means for "receivingV successive ones of a pluralityk yoie boxes and arranging thesame in vertically stacked relation,

and pertains more particularly to a device which will receive the successive 'boxes and' place them successively at thebottom of a stack which is being formed, until the desired number ofboxes Y in the stackhave been arranged, and then'cause the assembled stack to -be discharged from the device as a unit.

One of the particular objects of this invention is to provide a devicewhich will arrangea plurality of boxes in stacked relation without excessive jarring or disturbance of the contentsfof the boxes, a feature'ofV particular importance where thev device-r is employed to'Y stack boxes of oranges or'other fruit which aresubject'to decayI and spoilage in the event off bruising. Y

"A further object of tlieinvention-` is to provide a devicev ofv the character described,-'which maybel'utilized in close association with afdeliveryl conveyor `in position to receive boxesdelivered thereby, to receive and arrange suchl boxes in stacked relation, and deliver the stacked assembly, ina substantially vautomatic* fashion;

In the handling of boxes-containing fruit, such as oranges, it isfnecessary in the conservation of space to stack the `boxes to asgreat a height as may be accomplished by manual labor, and where the boxes have not beenflidded, i. e. thel pack made-secure, the fruit is necessarilyloose and is subject todislodgment to alevel above thatcp of the box as a box is literally thrown on top` of a fairly high stack. When the next box-"is tossedpn top of a box containing such dislodged fruit, ther-ruit projecting above the top of the box is subject to bruisingv and consequent rapid spoilage. In view of this' typefof diiiicultyin the handling of boxesv containing loosely packed fruit, itis a particular object of this invention to provide adevice which willY formv a stacksof boxesfby placing the succeeding boxes atthe bottom of the stack as it is being formed, under conditionsA such that the bottom box' in processzof stacking isnever subjected to forces or movement such as to dislodge the fruit from the positiony it occupies whenv deliveredtoY thev stacking device, thereby avoiding fruit `damagey of the type above described.

The device of the present invention may comprise, in general, a guide means `definingavertically Vextending hollow shaft khaving-internal transverse dimensions consonant with'l thetransverse dimensions of the boxes tobe stacked .and provided adjacent its lowerv end' with an opening' through which the boxes `may be supplied. iny succession at a given loading level', togetherv with carriage means adapted -toreceive a so` delivered boxlandY raisel the same upwardly within the hollowfsh'aft tota locating level'. Thendevice further comprises means for returning-the; carriage to the loading level `forfthereception'of' a. second box, carrying 'such secondA box' upwardly typical embodiment, or will be apparent from,y

into contact with the rst box locating level and thereafter raise the rst box and't'he second Vbox in af stacked' relationship until the' secondY box is disposed at the locating level; Means are provided forA repeating this procedure until the desired number of boxes have been disposed in stacked relation, after which the entire stack isflowered to the floor or any other suitable levelr for discharge from the shaft asv an assembledstack.4

VOther features of the invention will be brought out` in the ensuring specic description of a suchdescription. The accompanying drawings illustratethis typical embodiment in detail, and referring thereto: v

Fig.. 1 is a three-quarter view of-the stacking device of this invention, taken from the loading side; Y Y

Fig- 2v is a three-quarter view taken from the discharge lside;

Fig. 3 is a partly broken away vertical section as takenon line 33fof Fig. 2;

Fig. 4 is a fragmentary vertical section in the sameplane as the left side of Fig. 3, taken in the Vicinity of line IG-6 in Fig. 3, showing a position adopted vby the boxes during the stacking operation;

Fig. 5'is a View corresponding to Fig. 4 showing an` alternative position adopted by the boxes;

Fig; Gis a `fragmentary transversesection asV taken on-line--dn Fig. 3;

Fig.` '7 is a ragementary vertical section as taken on line 1-1 in Fig. 3;

Fig.f8 is a fragmentary transverse section as taken: on line 8;-8 in-Fig. 6;

Fig. 9' l isa 4fragmentary vertical section as takenon line 9-9 of Fig. 3;

Fig. 1'0 isa diagrammatic showing of one side of the stacking device showngthe relative location of operating circuit control switches which maybe employed to secure a substantially automaticoperationof the device; and

Fig.` 1l is a schematic showing'of a form of control circuit which may be employed for operation of the .stacking device of this invention.

Referringto the drawings, the device may comprisea plurality of vertical members l'arranged to denne a vertically extending shaft 2V having internalk dimensions consonant with the transversedimensions of the style of box which is to be handled in a'stacking operation. The drawings show various boxes in process of being stacked, which are indicated generally by the reference numeral 3.

The members IA are mounted on or securedto a 'oor'structure it above a chain conveyor 5 havinglanactive run located slightlyy above they floor levelr in position to carry away a stack of boxes lowered thereupon; such chain conveyors beingv in common use inA packing houses, no detailed showingythereof is made herein. At a suitable height abovetheool, aS may be required for disposed at the Y 3 cooperation with a particular conveyor assembly, the side of the shaft 2 is cut away to provide a receiving opening 6 through which boxes may be passed from an adjacent conveyor 1. Usually a main conveyor will be provided as at 8 which will carry boxes to any given stacking device, and` the conveyor 'I will be employed to receive the boxes from the main conveyor 8 and to carry` them to the shaft 2.

Within the shaft 2 a vertically movable carriage is provided for the purpose of receiving the boxes delivered through the opening 6, and this carriage may comprise a pair of spaced platform members 9 threadedly mounted on lead screws I0 at the respective sides of the structure, the lead screws being journaled at their bases as at I I and provided with power operating means I2 which may conveniently be located at the upper end of the frame dened by the uprights I. Each of the platform members is provided with a plurality of supporting rollers I3 so positioned as to underlie the respective longitudinal ends of the nether surface of the box 3 delivered from the conveyorV 'I through the opening 6. Suitable guide rollers I4 may be provided for engagement with the adjacent uprights I, to cause the platform members 9 to be constrained in relative position during the rotation ofthe lead screws I in the operation of the device. l

When a box is delivered from the conveyor 'I through the opening 6 onto the carriage means defined by the platform members 9, the operating means I2 is caused to be energized in such direction as to move the carriage means upwardly in a start of the stacking operation. Referring to Fig. 3 in particular, the box received by the carriage means is caused to be carried upwardly to approximately one and one-half box heights, adjacent which level means are provided for supporting the box against downward movement while the carriage means is lowered to the loading level as -dened by the conveyor "I, Such supporting means, hereinafter referred to as locating means, is of a character such as to be readily moved out of locating position with respect to a superior box when a succeeding box is raised toward Vlocating position. By way of example-we have illustrated such locating means as com-l prising a plurality of locating rollers I mounted on suitable brackets I'G attached to the respective corners of the framework defining the shaft 2 and adapted to engage a box at its four corners. These rollers are carried by axial pins I1 located in guide slots I8 so shaped as to permit upward and outward movement of the rollers upon engagement by the upper edges of an inferior box, the amount of movement permitted by the guide slots I8 being such as to locate the inwardly directed peripheries of the rollers I5 inwardly of the ends of the box 3 in their lowered position and outwardly of the ends of the box in their raised position. The slots I8 are preferably provided with vertically extending inner end portions I8a adapted to resist outward movement of the rollers I5 under the load imposed by a box 3 (Fig. 3).

We preferably provide means for lifting the rollers I5 clear of the boxes 3 to a position such as they will not interfere with they lateral discharge of a stack from the shaft 2 as hereinafter described, and such means may comprise a solenoid I9 mounted on each of the brackets I6 and having an actuating rod I9a carrying a f oot 20 adapted to engage the lower edge of the roller I5, the solenoid being mounted on the outside of t the bracket andy extending into the space within the bracket into'engage'm'e'nt with thevroller I5 through a slot I6a in said bracket. This structure t is omitted in Figs. 1, 2, 4, and 5, shown in small scale sectionally and in elevation in Fig. 3, and shown in greater detail in Figs. 6 and 8. Operation of the solenoid I9 is adapted to cause the roller I5 to adopt the dot-dash position of Fig. 8. Itis not necessary that the solenoid be of sufcient strength to pull the roller I5 out from under a located box 3', inasmuch as it is only necessary to lift the rollers I5 clear of a box when the roller-box relation is that of Fig. 4.

When the carriage means is raised to place a box ,on the locatingY rollers, the rollers move upwardly and laterally. after the mannershown in Figs. 4 and 8, and :when the nether edges of the box clear the rollers, the rollers drop inwardly in position Vto be engaged by the corners of the box as the carriage means is returned toward the loading level, as shown in full lines in Fig. 8. When a box has already been located on the rollers I5, the next succeeding box will engage the rollers (see dot-dash lines 3 in Fig. 8) and push them out of contactwith the box which they had been supporting, and the box or boxes above the position of the rollers will fall against the upper edge of this next succeeding box. 'I'he continued upward movement of the carriage means then carries the whole stack upwardly until the lower edge of the lowest box clears the vrollers I5, as to the position of Fig. 5, at which timey the carriage means is lowered until the bottom corners of such box engage and are located by the rollers, after which the carriage means is returned to the loading level.

Assuming that the boxes are to be stacked nine in a stack (a height commonly in use in citrus Vpacking houses), only eight boxes have to be carried as high as the locating level defined by the rollers I5 inasmuch as the ninth box has merely Ato be carried upwardly an amount sufficient thatthe rollers I5 are pushed out of the way and the top eight boxes released into engagement withthe top of the ninth box. (To conveniently control the operating drive mechanism I2, circuit control means can be located in position to be engaged by the top box of a series instead of requiring the carriage means to be raisedl past the locating rollers to the locating level, as will hereinafter more particularly be described.) After the desired number of boxes have been placed in stacked relation, the entire stack is then lowered by lowering the carriage means clear to the floor so that the bottom box of the stack (as shown in dot-dash lines at 3a in Fig. 3) is brought into contact with the chain conveyor 5. The downward movement of the platform members 9 is preferably slightly greater than that just sufficient to place the bottom wall of the bottom box on the conveyor 5, so as to insure that there will be no opposition to the withdrawal of the stack.

Inasmuch as the stack is withdrawn as a unit, we .preferably provide movable guide means or gates 2I at the rearward side of the shaft 2, which will function to retain the stacked boxes within the shaft 2 until it is desired to remove the Ystack as a unit, and these gates 2I may be pivotally mounted on the rearward frame members I, as at 22, and may be operated through the agency of a gear and crank assembly 23 located below the floor level and operated by a lever arm 24 whichis engageable by the bottom box of the stack as.` the stack is lowered to the position shown acca-11.1y

in. 'dot-dash lines in Fig., This gateoperating mechanism is illustratedin greater' .detail in Fig. 9, and may comprise the lever 24 which is linked through arm 25 to a bell crank 26 carried on a transverse shaft 21 carrying a. bevel gear 28 meshing with a bevel gear 29 .carried on an operatingshaft 3I secured to one of the gates 2|, it

being. appreciated that a drive assembly for eachv of the gates may be provided, or that one of the gates. may be direct-driven and the other operated `by a linkage mechanism.

. When the stack of rboxes has been withdrawn from the shaft 2 by the chain conveyor 5, the lever 24 will be returned to the full line position of Fig'. 9, as through the agency of an operatingspring 32, and this return movement may be utilized to institute upward movement of the carriage means to the loading level.

The drive means I2 is illustrated as comprising areversible electric motor 33 driving a cross shaft 34 which is geared to the operating or lead screwspl at gear boxes 35. Fig. 11 shows one form of voperating circuit which may be employed to secure a fully automatic operation of the stacking mechanism, although it will be appreciated that the device may be manually operated by the provision of conventional up and down switches available tothe operator who-iis responsible for selecting a particular type of box-off the conveyor 8 and causing it to move over the conveyor 'I into the shaft 2. Fig. 10 represents the location of a plurality of switches' whichare operable by the carriage means or the boxes in the stack, S1 representing a normally Open double-pole switch located so as to be actuable by -a jbox 3 when it is received by the carriage. means after delivery from thev conveyor 1.- It is intended that thisswitch willremain in closed or operated condition so long as a box is present on the carriage means. `he represents a doublepole switch having a set of normally closed contacts anda set of normally open contacts located so as to *be operable by one of the platform members 9 when the carriage means is raised to a position such vas that-shown in Fig. in which the bottom of a box being stacked is raised above the level of the rollers I5. S3 isa double-pole normally closed switch which maybe located in position to be actuated (opened) by one of the platform members as when the carriage means reaches Vthe loading level, i. e. when` the rollers I3 are aligned with conveyor 1. `Si is a doublepole switch` comparable to that employed at S2,

Y i. Ae..havinvg a pair of normally closed and a pair (if-.normally open contacts, Vwhich is positioned near the top ofthe shaft 2 Where it is actuable byjtheftop edge of a stack which has been brought tothe desired height by the placement of the last box on the bottom. As brought out above itzisunnecessary that the carriage means be raised as high for the engagement of the top of the stack .upon switch Si as it is vto locate a box on the locating rollers I5, it being necessary only toraise the bottom box high enough to clear the locating rollers from under the nextsuperior box (Fig. 4 illustrating such a position), and then-continue the upward movement enough to carry the-stack of boxes upwardly a short distance-into contact with S4. S5 may comprise a four-pole switch having three sets of normally closed contacts and one set of normally open contacts, and is preferably located so as to be engageable by one of the platform members 9 in itsf lowermost positionisuch as that indicated indot-dash lines in Fig. 3). Ss-may comprise a 61. single-pole normallyopen switch .actuable :by the leverzeat a; point Vinterrnediatge the full line and .dot-.dash .line .positions thereof; .shown in Figlg. L' i In theillustrated .circuit arrangement.. three relays R1, R2. and Re are provided, R1 controlling.

the upVirnovement of the carriage, Rzqcontrolling the zdown movemenhandRs being utilized in Vvthe operation oflowering the, Vstack onto .the

6I ofRz, thence through line 52 to line lead .6.3.

This .energizes R1. causing line lead 5I to be connected through line 64, jumper 65.' contact-:6.6.

f line 6-7, thermal-relay TR1. ,coil `68 of up control switch `assembly 69,y thence v .to lline lead. 5:3. The .001156 is then connected. :by operation of R1,- through movable contact-"I0 of the makebefore-break combination lll- 5.3, 54, direct to line 64 which is connected to line lead 5I., holding the relay Riclosed independent of Si so Vlong zas Sz and Si remain closed. When the carriage Vfis at the loading level, S3 is held open, and the lower. (normally closed)l contacts thereof' hold open the retur-ncircuit for coil 5 3 inasmuch as the latter contacts `are in series withl S2. For this reason'a lower set of normally open contacts are Yprorvioledjfor S1 i-n position `to Ashunt the latter contactsrof 4S3 until the carriage has fmovedupwardly a sufficient amount to close S3. v

Operation of motor M in lan upfV direction raises the carriage andvits box until thev bottom of the box has been carried vabove the locating rollers I5, at which .position switch S2v is Vengaged,I opening the upper pair of contacts Vand closing thelower pair. .Opening the upper pair of, contactsv opens `the return circuit for .thefcoil 5E of R1, opening the .supply lead at GSand stopping motor M. Closing the lowercontacts ofSz, connects line lead 5I through line .'II to vthe energizingcontact 'l2 of R2, thence through contact'fline 14 to coil 15, thence througlivline .16 t'o'control'contactll on Ri, through lines'18 and '19 through the upper normally closed contacts of Se to line lead`63. Operation of 'Rzcloses the circuit to down switch 80, from line lead 5I through leads 81 .through the lowermost-normally closed contacts; of Sq, through jumper 82, contact 83V and lead l84 to thermal relay TR2, thencejto coil 85, causing l themotor M to urun in the "down"'direction.1 Ihis ,lowers the carriage away from the rst box locatedl on the locating -rollers I5, and returns Ait to loading position, at which timeiSa is opened, opening thereturn circuit for coil 'I5 of R2, and de-energizing motor M. f l

*The `device fis now in condition for V'receiving the second' vbox-within the carriage, which closes Si and'causes a repetitioni of the operation. Two boxes are Anow supported'on the locating rollers, theiirst resting on top of the second. After a given `number of such repetitions, `so kthat a desired number of boxes, sayeight, 'have been-supported `upon the locating rollers, and the .ninth box is received bythe carriage, the resulting 7 upward movement of the carriage, afterrengagement' of. the bottom of the eighth box by the top of the ninth, causes the top of the iirst box (on top of the stack) to engage S4. Operation of S4 opens contacts 59, opening the return circuit forl coil-56 of R1, stopping -the upward travel of `the assembly. Operation of S4 also causes nthe lower normally open contacts to close, connecting line lead-| through leads 86.to energizing contact 81 of Ra, thence through contact 88, lead 89, coil 90, lead 9| to the middle normally closed contacts of S5, and lead 92 to line lead 63. OperationA of R3 causes contact 93 to close, connecting line lead 5| through'leads 94 and 95 to energizing -contact 12 of R2, causing the motor M to be opratedrin the down direction and lowering the carriage. Upon operation of Ra, contacts 96 close before

contacts

81 and 88 open, and hold R3 by connection direct to line lead 5| through lead 94 so that de-operation of S4 will not interruptthe downward travel of the carriage. Operation of R3 also closes contact pair 91 of R3 connecting solenoids L1, L2, L3 and L4 across line leads 5| and 63, lifting the locating'rollers |5to their upper most positions, clear of the stack. Solenoids L1--L1 represent the solenoidsshown at I9 in the drawings. Contacts 98 shunt the upper normally closed .contacts of S3. so that opening of S3 will not cause R11 to be de-energized when'the loading level is reached by the carriage, which therefore descends 'to its lowermost position (dot-dash lines in Fig. 3), where'Ss is operated. Operation of S5 opens the return circuit for coil 90, at 9|92, de-operating R3, which in turn de-operates'Rz and stops motor M, Inasmuch as it is preferred that the locating rollers |51 remain out of'engagement with the stack of boxes at this lowered position, S5 is preferably provided with a lower normally open set of contacts 99 which close to shunt contacts 91 and retain energization of solenoids L1-L4.- f "When the ,stack is lowered to thislowermost position of the carriage, opening gates 2| by operation of the gear and crank assembly 23, the Afloor chain conveyor 5 carries the staclcaway, and as the lever 24 is releasedby removal of the stack, theswitch Ss is momentarily closed, connecting line lead 5| through leads |00, normally closed contacts |0|, lead |02 and Vlead |03 toenergizing contact 53 Vof R1, starting .an upward movement of thev carriage, relay R1 holding through lead 54 and contact 10.' When thecarriage leaves its lowermost position, it goesV out of contact with Ss', opening the 'circuit to the solenoidsL1-'L4. V As the carriage isbrought up to .loading position, S3 is contacted, opening the lower set of normally closed contacts (in series kwith the normally closed contacts of S2 and S4) breaking the return circuitfor'coil 56 of R1 and stopping the carriage. In this position there is noA box present in the carriage, hence S1" will not be operated and the shunt for the lower contactsof Sais not connected.

It will be appreciated that the specific structure herein shown and above described is to be considered as illustrative only. and not limitative upon our invention, the broad scope'of our invention being deiined in the subjoinedclaims. For example, while we have shown a preferred form of locating means to hold the stacked'boxes in the shaft as comprising roller members l5, numerous other forms of locating latches maybe visualized by another. skilledfin such art, and

may vbe substitutedl therefor vwithout departure from our broad concept ofthe structure.

We claim: e

1. In a box stacker,v the combination of an elevator adapted to be reciprocated vertically between a box receiving position and an upper position to permit this to receive boxes and elevate the same in the formation of a stack; latch meansv for supporting said stack as it is thus progressively formed; means for delivering boxes horizontally in a given direction onto said elevator; means forreceiving said stack from said elevator after it is formed and discharging it out of said stacker in the same direction as that in which said boxes were delivered to said stacker; a. pair of gates disposed alongside opposite edges and in front of the path along which said elevator operates vertically, said gates acting as limit stops for individual boxes being fed onto said elevator and as stack guides; and means operating in timed relation with the delivery of said stack from said elevator onto said stack discharge means for displacing said gates from in front of said stack to permit the latter to be Idischarged from said stacker.

2. A combination as in claim 1 in which said stack discharge means comp-rises a conveyor onto which said elevator deposits said stack by travelling downwardly below its box receiving, position, said means for displacing'said gates being actuated by engagement with the lower end of said stack as the latter is lowered onto said conveyor.

3. In al box stacker, the combination of: an elevator adapted to be reciprocated vertically between a box receiving position and an upper position to permit this to receive boxes and elevate the same in the formation of a stack; latch means for supporting said stack as" it is thus progressively formed; means for delivering boxes horizontally in a given direction onto said elevator; means for discharging saidI stack out of said stacker after it is formed; a pair of gates disposed in Vfront of opposite edges of said stack as it is being formed to prevent said stack falling in the direction in whichitisto be discharged from said stacker; and means operating in timed relation with the discharge of said stack from said stacker for displacing said gates from in front of said stack to permit the latter to be discharged from said stacker. v

4l. A combination as in claim 3 in which said means for displacing Asaid gates is actuated by vertical movement of the completed stack.

5; A combination as in claim' 3 in which said stack, after being formed, is lowered downwardly on said elevator onto said stack discharge means and in which said means for displacing said gates from in front of said stack is actuated by said stack as the latteris so lowered.

6. A combination as in claim 3 in which said means for displacing said gates from' in front of said stack is actuated coordinately with the discharge of said stack from said stacker and just prior tothe commencement of said discharge movement of said stack.l

'7. A combination as in claim 3 in which said gates are pivotally supported on vertical axes and are swung away from in front of said stack in displacing said gates to permit the stack to be discharged from the stacker.

8. In abox stacker, the combination of an elevator adapted to be reciprocated vertically between a box receiving position and an upper position to permit this to receive boxes and elevate the same in the formation of ,a stack; latch means for supporting said staclr as it is thus progressively formed; means for delivering boxes horizontally in a given direction onto said elevator; means for discharging said stack out of said stacker, after it is formed; guide means for the ends and backside of said stack as it is being formed; guide means disposed in front of said stack as it is being formed to prevent said stack falling in a direction in which it is to be discharged from said stacker; and means operating in timed relation with the discharge of said stack from said stacker for displacing from in front of said stack said front guide means to permit said stack to be discharged from said stacker.

9. In a box stacker, the combination of: elevator means operating to form a stack in a given vertical path; means for discharging said stack out of said stacker after it is formed; front guide means disposed in front of said stack when the latter is being formed to prevent said stack falling in the direction in which it is to be discharged from said stacker; and means operating in timed relation with the discharge of said stack from said stacker for displacing said front guide means from in front of said stack to permit the latter to be discharged from said stacker.

10. In a box stacker, the combination of: elevator means operating to form a stack in a given vertical path; means for discharging said stack out of said stacker after it is formed; guide means disposed at the ends and backside of said stack for guiding the latter as it is being formed; front guide means disposed in front of said stack when the latter is being formed to prevent said stack falling in the direction in which it is to be discharged from said stacker; and means operating in timed relation with the discharge of said stack from said stacker for displacing said front guide means from a front of said stack to permit the latter to be discharged from said stacker.

11. In a box stacker the combination of an elevator adaptedV to be reciprocated vertically between a box receiving position and an upper position to permit this elevator to receive boxes and elevate the same in the formation of a stack; latch means for supporting said stack as it is thus progremively formed; means for delivering boxes horizontally in a given direction to said elevator; a horizontal conveyor for discharging said stack out of said stacker after it is formed; front guide means disposed in front of said stack as it is being formed to prevent said stack falling in the direction in which it is to be discharged on said conveyor from said stacker; means responsive to the stack, being formed as aforesaid by said elevator, reaching a given height to release said latch means and to lower said elevator with said stack thereon to deposit said stack onto said conveyor; mechanism for disposing said front guide means away from in front of said stack; and a member, responsive to vertical movement of said completed stack on said elevator, to actuate said mechanism to dispose said front guide means away from in front of said stack.

12. A combination as in claim 11 in which said member is disposed beneathsaid stack and is engaged by said stack as it descends while being lowered onto said conveyor whereby said member is shifted to actuate said mechanism and dispose said front guide means away from in front of said stack.

13. A combination as in claim 11 in which said guide means comprise a pair of gates mounted pivotally on axes disposed on opposite sides of said stack as the latter is being formed; and means normally swinging said gates into positions in front of said stack to guide the latter during its formation and prevent it falling in. the direction in which it is to be discharged on said conveyor from said stacker, said member being responsive to vertical movement of said completely formed stack, to overcome said normally operative gate swinging means and swing said gates away from in front of said stack.

14. A combination as in claim Il in which said guide means comprise a pair of gates mounted pivotally on axes disposed on opposite sides of said stack as the latter is being formed; and means normally swinging said gates into positions in front of said stack tov guide the latter during its formation and prevent it falling in the direction in which it is to be discharged on said conveyor from said stacker, said member being responsive to vertical movement of said completely formed stack, to overcome said normally operative'gate swinging means and swing said gates away from in front of said stack, said stack responsive member tbeing mounted beneath said stack so as to be engaged by said stack and be shifted downwardly thereby as said stack is lowered onto said conveyor.

l5. In a box stacker, the combination of: an elevator adapted to be reciprocated vertically between a box receiving position and an upper position to permit said elevators to receive boxes and elevate the same in the formation of a stack; latch means for supporting said stack as it is thus progressively formed; means for delivering boxes horizontally to said elevator; means for receiving said stack from said elevator, after it is formed, for discharging said stack from said stacker; guide means disposed in front of said stack, as it is being formed, to prevent said stack falling, during its formation, in the direction it is subsequently to be discharged; and means responsive to vertical movement of said elevator and stack in the stack completing reciprocation of said elevator, to displace said guide means from in front of said stack.

16. In a box stacker, the combination of elevator means adapted to form a stack in a given vertical path; means for receiving said stack from said elevator, after it is formed, for discharging said stack from said stacker; guide means disposed in front of said stack as it is being formed to prevent said stack falling, during its formation, in the direction it is subsequently to be discharged; and means actuated by vertical movement of said elevator and stack, and operating between the completion of said stack and said discharge thereof, to displace said guide means from in front of said stack.

BRUNER R. DAVES. WARREN L. IRVINE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 158,976 Pfautz et al Jan. 19. 1875 1,292,636 Parker Jan. 28. 1919 1,564,536 Davis et al Dec. 8, 1925 2,266,170 Currie Dec. 16, 1941 2,313,478 Neja Mar. 9, 1943 2,333,479 Graf Nov. 2, 1943