US3877592A

US3877592A - Bakery product depanning apparatus

Info

Publication number: US3877592A
Application number: US392939A
Authority: US
Inventors: Norman O Krenke; John R Baker; Dewitt Sims; Carl R Skarin
Original assignee: Baker Perkins Inc
Current assignee: APV Baker FM Inc
Priority date: 1973-08-30
Filing date: 1973-08-30
Publication date: 1975-04-15
Anticipated expiration: 1992-04-15

Abstract

Depanning apparatus for removing bakery products, such as bread loaves, from pans on a product-supplying conveyor and transferring the loaves to a remote location wherein a transfer conveyor mounting depending, resilient, product gripping, vacuum cups moves along the bottom of a downwardly opening vacuum box, having an upstream end connected to a vacuum source. A partition divides the box into upstream and downstream chambers and has a restricted opening sized to permit at least a predetermined amount of air to be evacuated by the vacuum source from the downstream chamber via the upstream chamber to maintain a minimum vacuum level in the downstream chamber. A second blockable opening is also provided in the partition for selectively increasing the vacuum applied in the downstream chamber.

Description

United States Patent Krenke et a1.

Assignee:

Filed:

BAKERY PRODUCT DEPANNING APPARATUS Inventors: Norman 0. Krenke; John R. Baker,

both of Saginaw; DeWitt Sims, Burt, all of Mich.; Carl R. Skarin, Southern Pines, NC.

Baker Perkins Inc., Saginaw, Mich.

Aug. 30, 1973 Appl. No.: 392,939

US. Cl 214/309; 198/179 Int. Cl A2lb 3/18 Field of Search 214/309; 198/179;

References Cited UNITED STATES PATENTS Whallon 294/64 R X Gendron 198/179 X Primary ExaminerRobert J. Spar Assistant ExaminerGeorge F. Abraham Attorney, Agent, or FirmLearman & McCulloch [5 7 ABSTRACT Depanning apparatus for removing bakery products, such as bread loaves, from pans on a productsupplying conveyor and transferring the loaves to a remote location wherein a transfer conveyor mounting depending, resilient, product gripping, vacuum cups moves along the bottom of a downward1y opening vacuum box, having an upstream end connected to a vacuum source. A partition divides the box into upstream and downstream chambers and has a restricted opening sized to permit at least a predetermined amount of air to be evacuated by the vacuum source from the downstream chamber via the upstream chamber to maintain a minimum vacuum level in the downstream chamber. A second blockable opening is also provided in the partition for selectively increasing the vacuum applied in the downstream chamber.

4 Claims, 6 Drawing Figures li l Al I imlullllilp nuliiIl lliiln...

r nllll nnmlil J ni'lHl l1 Fu SHEET 1 BF 2 FIGZ BAKERY PRODUCT DEPANNING APPARATUS FIELD OF THE INVENTION This invention relates to bakery product transfer apparatus including a vacuum cup carrying conveyor covering the downwardly opening side of a vacuum box having a plurality of vacuum chambers, and more particularly to apparatus for controlling the vacuum level in the chambers.

BACKGROUND OF THE INVENTION The present application discloses an improvement over the embodiment disclosed in U.S. Pat. No. 3,809,265 having the same assignee as this application, and said patent is incorporated herein by reference. In said patent, a depanning apparatus is illustrated, including a downwardly opening suction box incorporating a pivotal shoe which selectively closes off bellowstype suction cups communicating with the downstream portion of the box during startup so that the air drawn into the vacuum box through the upstream vacuum cups, communicating with the upstream portion of the box, will be of sufficient velocity that valve plates provided in the upstream vacuum cups will close them when the cups are not sealed to a product.

It is an object of the present invention to provide apparatus of the type described including a vacuum box divided into upstream and downstream chambers and including mechanism for providing at least a minimum vacuum in each of the chambers and for selectively increasing the vacuum level in the upstream chamber.

It is another object of the present invention to provide depanning apparatus of the type described which includes segregated upstream and downstream vacuum chambers and mechanism communicating the chambers so that air will flow from the downstream chamber to the upstream chamber at such a rate that the vacuum will build at a faster rate in the upstream chamber.

It is another object of the present invention to provide apparatus of the type described, including a vacuum box having a plate dividing the box into upstream and downstream chambers, a vacuum source communicating with the upstream chamber, an opening in the plate dimensioned to permit sufficient air to be withdrawn from the downstream chamber to maintain at least a minimum vacuum in the downstream chamber while permitting the vacuum in the upstream, chamber to build to a higher predetermined level at start-up, and a second blockable opening in the plate which, when opened, permits sufficient air to be withdrawn from the second chamber that the vacuum level in both chambers is essentially the same even though the second chamber is not completely sealed.

Another object of the present invention is to provide transfer apparatus of the type described wherein a vacuum box, including upstream and downstream chambers, has air evacuated therefrom by a single suction fan communicating with the upstream chamber.

It is another object of the present invention to provide transfer apparatus of the type described which will minimize the power required to operate the machine and will operate at a minimum noise level.

It is another object of the present invention to provide transfer apparatus of the type described which includes a pair of vacuum chamber sections in each of which the vacuum level is substantially constant throughout the entire length of the chamber section.

It is another object of the present invention to provide transfer apparatus of the type described which will efficiently operate at a substantially steady level without vacuum surges.

It is an object of the present invention to provide a system of the type described which will move a minimum volume of air to create and maintain the desired vacuum condition, and hence will require a smaller fan and a smaller, less costly, fan driving motor.

Other objects and advantages of the present invention will become apparent to those of ordinary skill in the art as the description thereof proceeds.

SUMMARY OF THE INVENTION Apparatus for transferring products, such as bread loaves, from'a product-supplying conveyor and transferring them to a remote locationcomprising a vacuum box divided by a partitioning plate into individual upstream and downstream vacuum chambers, a vacuum source communicating with the upstream chamber, restricted opening in the plate, communicating the upstream and downstream chambers, and of at least such size as to permit sufficient air to be evacuated from the downstream chamber to maintain a minimum vacuum in the downstream chamber when air is evacuated from the downstream chamber via the upstream chamber, and mechanism for selectively increasing the air evacuated from the downstream chamber via said upstream chamber to build the vacuum level in the downstream chamber above the minimum level to the desired level.

The present invention may more readily be understood by reference to the accompanying drawings, in which:

FIG. 1 is a side elevational view of vacuum box apparatus constructed according to the present invention, part of the vacuum box being broken away to expose internal parts thereof;

FIG. 2 is a sectional, top plan view, taken along the line 2-2 of FIG. 1;

FIG. 3 is an enlarged, sectional end view, taken along the line 33 of FIG. 1;

FIG. 4 is an enlarged, opposite, side elevational view, taken along the line 44 of FIG. 2;

FIG. 5 is a further enlarged sectional side view, taken along the line 55 of FIG. 3, particularly illustrating one form of bellows cup which is utilized; and

FIG. 6 is a schematic diagram of a typical electrical control circuit for controlling the operation of the apparatus illustrated in FIGS. 1-5.

DESCRIPTION OF THE INVENTION Transfer apparatus, generally designated 8 and constructed according to the present invention, is mounted on a frame, generally designated F, including posts 10 spanned by end rails 12, upper side rails 14, and lower, vertically inclined side rails 16.

The transfer apparatus 8 is provided for transferring loaves of bread B, supported in pans or pan sets 18, from a supply conveyor, generally designated 20, to a discharge conveyor, generally designated 22. The supply conveyor 20 may comprise an endless belt 24 trained around a pair of frame-supported drive rolls 26 which are fixed to shafts 26a which are driven by a motor M (FIG. 6) to move the belt 24 in a direction represented by the arrow a, and thus move the pan sets 18 and loaves B in a downstream direction, or forwardly. The discharge conveyor 22 may likewisely comprise an endless belt trained around a pair of frame-supported drive rolls 27 which are driven to move the discharge conveyor belt 25 in such a path as to move the discharged loaves B in the direction of the arrow b. An idler roll 28 is journaled on the frame F to cause the upstream portion 25a of the discharge conveyor belt 25 to move in a slightly upwardly inclined path.

The transfer or depanning apparatus 8 includes a downwardly opening suction box, generally designated 30, mounted on the side rails 16 by laterally projecting plates or bars 32 fixed to the side walls of the box 30. The box includes a pair of end walls 34 and a pair of side walls 36, spanned by a top wall 38.

To evacuate air from the vacuum box 30 and create a vacuum therein, a suction fan 40 is driven by a framesupported motor 41, and communicates with an air intake pipe or conduit 42 connected to the upstream end of the vacuum box 30. When the fan 40 is driven by the motor 41, it operates to evacuate air from the box 30 in the direction of the arrow c (FIG. 3) and discharges the evacuated air in the direction of the arrow d (FIG. 1).

An endless conveyor, generally designated 46, is mounted on the suction box 30 and includes a pair of endless chains 48 (FIG. 3), trained around sprockets 50 (FIG. 1), fixed to a pair of shafts 52 journaled by bearings 44 supported on the frame side rails 16. One of the shafts 52 is driven by a motor M1 (FIG. 6). The conveyor 46 includes a plurality of slats 56 (FIGS. 2 and 3) spanning the chains 48 having a plurality of laterally spaced apart, threaded apertures 58 (FIG. 5), each receiving an externally threaded mounting member 60 which supports a bellows-type resilient cup member 62. The resilient bellows member 62 engage and seal to the loaves B. The particular construction of the endless member 46 is more particularly described in applicants U.S. Pat. No. 3,l70,583, which is incorporated herein by reference.

The bellows cup connector members 60 each includes an air passage 61 therethrough communicating with the vacuum box chamber as the connector members pass along the underside of the box 30. When the ports 61 are open and the bellows cups 62 are not sealed to a loaf, air may be drawn through the passages 61 into the box 30 in the direction of arrows D.

To selectively interrupt the air passages 61, a valve member, generally designated 64, is preferably provided in each bellows cup 62 and includes a mounting clip member 66 slidably supporting a valve plate 68 for movement between the passage-opening position, illustrated in solid lines in FIG. 5, and the raised, passagesealing position, illustrated in chain lines in FIG. 5. The valve plate 68 has a predetermined weight. If the vacuum conditions in the vacuum box 30 are such as to cause a sufficient inrush of air, in a manner to be immediately described, in the direction of the arrows d, a sufficient differential pressure will exist across a given plate 68 to cause the plate 68 to move to the raised position illustrated in chain lines in FIG. 5 to close a passage 61.

The abutting slats 56 which move along the underside of the box engage a pair of bottom, side seals 70 fixed to the side walls 36 of the box 30 and a pair of end seals 70a fixed to the vacuum box end walls 34 by plates 72.

The vacuum box 30 is divided into an upstream chamber 74 and a downstream chamber 76 by a vertically inclined plate or partition wall 78 spanning the vacuum box side walls 36. The box dividing plate 78 includes an opening 79 of such size as to permit at least sufficient air to be evacuated by the fan 40 from the downstream chamber 76 through the upstream chamber 74 to hold the valve plates 68 passing under the downstream chamber 76, in the raised passage blocking positions, illustrated in chain lines in FIG. 5, once they have been moved to the raised position. The partition wall 78 mounts a duct 82 communicating with a second opening provided in the partitioning wall 78. A baffle plate 86 is fixed to a shaft 88 journaled in bearings 90 mounted on the duct 82 and the vacuum box 30. Thebaffle plate 86 is movable from the duct blocking position, illustrated in solid lines (FIGS. 1 and 4), and an air communicating position, illustrated in chain lines in FIG. 1, by a frame supported, solenoid actuated, double acting, fluid pressure operated cylinder 92, including a piston rod 94, pivotally connected to a link 96 fixed to the projecting end 88a of the shaft 88.

A differential pressure switch 98 (FIG. 1) is located in the downstream chamber 76 for sensing the vacuum condition therein, and is connected in circuit with a solenoid 920 (FIG. 6) for selectively directing fluid to the cylinder 92. When the vacuum in the downstream chamber 76 builds to a predetermined value, the solenoid 92a is energized to cause fluid to be directed to the cylinder 92 so that it will swing the baffle plate 86 to the open position illustrated in chain lines in FIGS. 1 and 4. When the plate 86 is in the open position, the pressure in the upstream and

downstream chambers

74 and 76 will substantially equalize even.

The opening 79 in the vacuum box dividing plate 78 is of such size that when the baffle plate 86 is in the closed position illustrated in FIG. 1, the vacuum in the upstream chamber 74 can build to a predetermined value substantially greater than the minimum vacuum level in the downstream chamber 76. When the vacuum builds to this predetermined level, the air passing through the passages 61 in the bellows cups passing under the upstream chamber 74 creates a sufficient differential pressure on opposite sides of the valve plates 68 to move them to the raised, passage blocking position illustrated in chain lines in FIG. 5.

The distance between the lower end of the dividing plate 78 and the front end wall 34 is just slightly greater than the width of a conveyor slat 56. The air being drawn into the upstream chamber 74 through the underlying bellows cups 62 is thus concentrated in the bellows cups 62 connected to a single slat 56 to quickly create a maximum pressure differential across the valve plates 68 therein so that the valve plates 68 will raise to the passage blocking positions. Once the valve plates 68 have been moved to raised positions as they pass under the upstream chamber 74, the minimum vacuum provided in the downstream vacuum chamber 76 with the door or baffle plate 86 closed will hold the plates 68 in raised position. Once the predetermined vacuum condition is reached in the upstream chamber 74, and the valve plates close and remain closed, the vacuum level in the downstream chamber 76 will rapidly build toward'the vacuum level in the upstream chamber 74.

To insure that the vacuum in the downstream section or chamber 76 will not exceed a predetermined value, a control valve, generally designated 105, is provided within an aperture or opening 106 in one of the side walls 36 of vacuum box 30 in position to open the downstream chamber 76 to atmosphere. The valve 105 includes a preferably cylindrical housing 105a which is open at both ends. The inner end of housing 105a is covered by a closure 107 which is normally springbiased to a closed position against a sealing gasket ring 10717 by a spring 108, connected at its inner end to a portion 1070 of cover 107, and at its outer end to an L-shaped slide 109. The slide 109, which is movable inwardly and outwardly in slide bearings 110 may be fixed in a designated position by a set or thumb screw lll, threadedly received in a threaded opening in one of the bearings 110 and engaging the slide 109 to hold it in adjusted position.

In the handling of soft crust products such as hamburger and frankfurter buns, for instance, which may be damaged by the application of high suction forces, it is necessary that vacuum forces in the chamber 76 be held below a predetermined level. When processing products of this nature, the slide 109 is set in a predetermined, adjusted position to impose a load on spring 108 of a nature to maintain the closure 107 in closed position, preventing air from being drawn into housing 106 and chamber 76, until such time as vacuum forces in chamber 76 reach a level to draw the closure 107 inwardly against the bias of spring 108 and admit air through opening 106. When other products are being processed, the slide 109 may be moved outwardly sufficiently so that the relief valve 105 is effectively blocked out of operation. In this situation, no vacuum capable of being developed in chamber 76 by the fan would draw the closure 107 away from closed position.

ln other instances, it may be desirable to utilize the control 105 when harder crust products are being processed. For example, the slide 109 can be set to counter or adjust the affect of baffle plate 86 to the desired extent, and also operates as a control, when set at a desired position. so far as opening 79, and the amount of air drawn through it, are concerned. The control valve 105 will always permit enough vacuum to build in chamber 76 to not only hold the valve plates 68 in closed position, but also to carry the product. Rather than having to design a vacuum box 30 of varied volume to suit each particular product it is desired to handle, a standard sized vacuum box 30 can be manufactured and control valve 105 can be utilized to control the vacuum level in a manner to most effectively and efficiently handle the particular product or products involved.

The motors for driving the supply conveyor shafts 26a, transfer conveyor shafts 52, and discharge conveyor shafts 27 are designated M, M1 and M2 (FIG. 6), and are connected across electrical power supply lines L1 and L2. A solenoid 92a for operating cylinder 92 is connected in series across the lines L1 and L2 with the pressure switch contacts 98a which close when a predetermined pressure is reached in the downstream chamber 76. When the baffle plate 86 opens, air can freely flow from the downstream chamber 76 through the upstream chamber 74 so that the vacuum condition in the downstream chamber will closely follow or equal the vacuum condition in the upstream chamber even though some of the bellows cups 62 are not completely sealed to a bread loaf B.

THE OPERATION If, during start-up, the baffle plate 86 is in the open position, illustrated in chain lines in FIG. 1, the volume of air entering the box 30 through the bellows cups 62 underlying both

chambers

74 and 76, is sufficiently great that the air pressure differential required to raise the valve plates 68 cannot be obtained. When the start switch 51 (FIG. 6) is closed at start up, the pressure switch contacts 98a close to energize the solenoid 92a which directs fluid to the cylinder 92 such that the baffie plate 86 is moved to the closed position to block the duct 82. The air flow from the second chamber 76 is thus restricted and the vacuum will rapidly build in the upstream chamber 74. When a designated level is obtained, the amount of air drawn, in the direction of the arrow D, through the bellows cups 62, passing under the upstream chamber 74, will cause a sufficient pressure differential to exist across the valve plates 68 that the plates 68 will raise to the closed position. Sufficient air passes at this time through the opening 79 in the chamber dividing plate 78 to maintain a minimum vacuum in the downstream chamber 76 to hold the valve plates 68 in the raised, or closed, positions.

The bellows cups 62 firstly engage the loaves B upstream of the box 30. If the cups 62, when they reach the leading portion of the vacuum box, are not in contact with and seal to bread loaves B, the valve plates 68 associated therewith will move up with the resulting inrush of air and close the passages 61 associated therewith. This only serves to increase the vacuum in both the upstream and

downstream chambers

74 and 76. If the cups 62 do not engage and seal to bread loaves B, the vacuum level in the downstream chamber 76 will approach the vacuum level in the upstream chamber 74. If the resilient bellows cups 62 engage and seal to the loaves B of bread on the supply conveyor 24, the loaves BB will move with the cups 62 to the discharge conveyor 27, where they are discharged when the vacuum is released in the cups as the cups pass the trailing edge of the vacuum box 30. If the bellows cups 62 completely seal to the tops of the bread loaves and the vacuum level in the downstream chamber 76 will be sufficient to hold the lifted bread loaves even though the baffle plate 86 remains closed, sometimes, however, the tops of the bread loaves present a rough or uneven surface, for example, when the loaves are covered with sesame seeds, and the bellows cups do not completely seal to the loaves. When this happens, air leaks through the bellows cups 62 into the downstream chamber 76 so that the vacuum level decreases. Since the opening 79 is relatively small, the veiocity of air being evacuated therethrough is relatively high, the volume of air being evacuated through the restricted opening 79 may be insufficient to hold the lifted loaves.

To insure that the lifted loaves will continue to be held by the bellows cups 62 as they pass along the underside of the downstream chamber 76 even during a condition in which the vacuum cups are not sealed, the pressure switch 98 is set to open the contacts 98a when the vacuum in the downstream chamber 76 builds to a predetermined level somewhat greater than that minimum vacuum required to hold the valve plates 68 closed. This causes the baffle plate 86 to open and increases the flow of air from the downstream chamber 76 to the upstream chamber 74. If the bellows cups do not completely seal to the tops of the bread loaves, the

inrush of air through the unsealed passages can be rapidly evacuated through the now opened duct 82. Normally, both the upstream and downstream chambers are brought to peak vacuum level before any product is fedto the machine.

lf the vacuum in the downstream chamber 76 should drop below a predetermined valve during any operation, the pressure switch 98 is operated to again cause the baffle plate 86 to close, temporarily blocking the duct 82 so that the vacuum will again build in the upstream chamber 74.

It is to be understood that the drawings and descriptive matter are in all cases to be interpreted as merely illustrative of the principles of the invention, rather than as limiting the same in any way, since it is contemplated that various changes may be made in various elements to achieve like results without departing from the spirit of the invention or the scope of the appended claims.

What is claimed is:

1. Transfer apparatus for lifting bakery product, such as bread loaves, from product supply conveying means and transferring them to a remote location comprising:

elongate, vacuum box means, adapted to at least partially overlie said product supply conveying means, including upstream and downstream vacuum chambers of predetermined volume separated by vacuum segregating means, each of said vacuum chambers including opening providing means along one side thereof;

vacuum source means communicating with said upstream chamber for evacuating air from said upstream chamber to create a vacuum therein;

said vacuum segregating means including opening means communicating with said chambers and being of such minimum size as to permit at least sufficient air to be evacuated from said downstream chamber to said upstream chamber to maintain at least a minimum vacuum level in said downstream chamber;

suction transfer means traveling forwardly along said one side of said chambers in communication with the chambers through said opening providing means to exert suction on said forwardly moving products to hold said products and transfer said products from said conveying means; and

means for selectively increasing the size of said opening means to increase the flow of air being evacuated from said downstream chamber to said upstream chamber to increase the vacuum level in said downstream chamber above said minimum level;

said opening means comprising a first fixed opening of such size as to permit sufficient air to be evacuated from said second chamber to at least maintain said minimum vacuum level in said downstream chamber, and a second opening; said means for increasing the size of said opening means in said segregating means comprising actuable means movable between a position covering the second opening and a removed position.

2. Apparatus for transferring products, such as bread loaves, from a forwardly moving product supplying conveyor to a remote location comprising:

a suction box, adapted to at least partially overlie said supplying conveyor, including upstream and downstream chambers separated by a dividing partition plate, each chamber having opening providing means along one side thereof;

vacuum source means communicating with said upstream chamber for evacuating air therefrom to create a vacuum therein;

product transfer means for transferring products from said supply conveyor including endless conveyor means having a run portion, traveling forwardly along the underside of said suction box, generally covering the opening providing means in said chambers;

a plurality of resilient product engaging suction members including individual passages opening through said endless conveyor means and communicating with said chambers through said opening providing means as they pass along said side of said box so that air is drawn into said chambers through said passages, said suction members including product engaging, resilient portions for sealing to the upper portions of the products on said supply conveyor;

valve means, associated with said passages, operative under a predetermined suction applied to them, for movement from an air communicating position to an air blocking position to reduce the air flow through said passages when they pass along said upstream chamber and said resilient portions are not sealed to a product;

said dividing plate including an opening of at least such size that sufficient air is evacuated from said downstream chamber to said upstream chamber to maintain at least a minimum vacuum in said downstream chamber so that said valve means is held in said air blocking position while passing along the second chamber;

a second opening in said dividing plate permitting sufficient additional air to be evacuated from said downstream chamber to said upstream chamber to permit the vacuum members passing along the downstream chamber to hold product on said members when said members are at least partially sealed to products and said valves are in said air communicating positions; and

means for selectively closing said second opening to limit the quantity of air evacuated from said downstream chamber and to increase the quantity of air evacuated from said upstream chamber to move said valves underlying said upstream chamber to said raised positions when said members are not engaging products.

3. Transfer apparatus for lifting bakery products, such as bread loaves, from a product-supplying conveyor and transferring them to a remote discharge location comprising:

a vacuum box assembly having elongate opening providing means in one side thereof, said vacuum box assembly and opening providing means including an upstream chamber portion communicating with a vacuum source which evacuates air therefrom, a downstream chamber portion, and means segregating said upstream and downstream portions, but including a passage communicating said upstream and downstream portions which is of at least such size as to permit sufficient air to be evacuated from said downstream chamber to said upstream chamber to maintain a minimum vacuum therein but permitting a greater predetermined vacuum to build in said upstream chamber;

perforate endless conveyor means, including a run section, having perforations, for traveling along the opening providing means in said vacuum box assembly from the upstream portion toward the downstream portion;

resilient product-engaging suction transfer means mounted on said conveyor means and including passages communicating with the perforations in said endless conveyor means;

valves associated with said passages and operative under a predetermined vacuum applied to them to move from an air communicating position to an air blocking position for selectively reducing air flow through said passages;

means for selectively reducing the vacuum in the upstream chamber portion to thereby increase the vacuum in the downstream chamber portion including additional opening means in said segregatendless conveyor means includes a plurality of transverse rows of apertures therethrough said upstream chamber along said transfer means having a length to communicate with substantially only a single row of apertures.

UNKTED STATES ATENT OFFICE errrrlmr r Patent No. 3 877 s 592 D t d April 15 9 1975 Norman 0 Krenke et a1. Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 20, after "startup" insert Column 1 line 24, delete "them".

Column 1, line 47, delete the Column 7, line 7, "valve" should read value Signed and sealed this 15th day of July 1975.

(SEAL) Arrest:

C. MARSHALL DANN RUTH C, MASON Commissioner of Patents Attestirng Officer and Trademarks

Claims

1. Transfer apparatus for lifting bakery product, such as bread loaves, from product supply conveying means and transferring them to a remote location comprising: elongate, vacuum box means, adapted to at least partially overlie said product supply conveying means, including upstream and downstream vacuum chambers of predetermined volume separated by vacuum segregating means, each of said vacuum chambers including opening providing means along one side thereof; vacuum source means communicating with said upstream chamber for evacuating air from said upstream chamber to create a vacuum therein; said vacuum segregating means including opening means communicating with said chambers and being of such minimum size as to permit at least sufficient air to be evacuated from said downstream chamber to said upstream chamber to maintain at least a minimum vacuum level in said downstream chamber; suction transfer means traveling forwardly along said one side of said chambers in communication with the chambers through said opening providing means to exert suction on said forwardly moving products to hold said products and transfer said products from said conveying means; and means for selectively increasing the size of said opening means to increase the flow of air being evacuated from said downstream chamber to said upstream chamber to increase the vacuum level in said downstream chamber above said minimum level; said opening means comprising a first fixed opening of such size as to permit sufficient air to be evacuated from said second chamber to at least maintain said minimum vacuum level in said downstream chamber, and a second opening; said means for increasing the size of said opening means in said segregating means comprising actuable means movable between a position covering the second opening and a removed position.

2. Apparatus for transferring products, such as bread loaves, from a forwardly moving product supplying conveyor to a remote location comprising: a suction box, adapted to at least partially overlie said supplying conveyor, including upstream and downstream chambers separated by a dividing partition plate, each chamber having opening providing means along one side thereof; vacuum source means communicating with said upstream chamber for evacuating air therefrom to create a vacuum therein; product transfer means for transferring products from said supply conveyor including endless conveyor means having a run portion, traveling forwardly along the underside of said suction box, generally covering the opening providing means in said chambers; a plurality of resilient product engaging suction members including individual passages opening through said endless conveyor means and communicating with said chambers through said opening providing means as they pass along said side of said box so that air is drawn into said chambers through said passages, said suction members including product engaging, resilient portions for sealing to the upper portions of the products on said supply conveyor; valve means, associated with said passages, operative under a predetermined suction applied to them, for movement from an air communicating position to an air blocking position to reduce the air flow through said passages when they pass along said upstream chamber and said resilient portions are not sealed to a product; said dividing plate including an opening of at least such size that sufficient air is evacuated from said downstream chamber to said upstream chamber to maintain at least a minimum vacuum in said downstream chamber so that said valve means is held in said air blocking position while passing along the second chamber; a second opening in said dividing plate permitting sufficient additional air to be evacuated from said downstream chamber to said upstream chamber to permit the vacuum members passing along the downstream chamber to hold product on said members when said members are at least partially sealed to products and said valves are in said air communicating positions; and means for selectively closing said second opening to limit the quantity of air evacuated from said downstream chamber and to increase the quantity of air evacuated from said upstream chamber to move said valves underlying said upstream chamber to said raised positions when said members are not engaging products.

3. Transfer apparatus for lifting bakery products, such as bread loaves, from a product-supplying conveyor and transferring them to a remote discharge location comprising: a vacuum box assembly having elongate opening providing means in one side thereof, said vacuum box assembly and opening providing means including an upstream chamber portion communicating with a vacuum source which evacuates air therefrom, a downstream chamber portion, and means segregating said upstream and downstream portions, but including a passage communicating said upstream and downstream portions which is of at least such size as to permit sufficient air to be evacuated from said downstream chamber to said upstream chamber to maintain a minimum vacuum therein but permitting a greater Predetermined vacuum to build in said upstream chamber; perforate endless conveyor means, including a run section, having perforations, for traveling along the opening providing means in said vacuum box assembly from the upstream portion toward the downstream portion; resilient product-engaging suction transfer means mounted on said conveyor means and including passages communicating with the perforations in said endless conveyor means; valves associated with said passages and operative under a predetermined vacuum applied to them to move from an air communicating position to an air blocking position for selectively reducing air flow through said passages; means for selectively reducing the vacuum in the upstream chamber portion to thereby increase the vacuum in the downstream chamber portion including additional opening means in said segregating means, and actuable means movable between a position blocking said additional opening means and a removed position permitting sufficient air to be evacuated from said downstream chamber to said upstream chamber such that the vacuum level in both chambers is substantially equal; and means responsive to a vacuum condition in one of said chambers greater than said minimum level for moving said actuable means to said removed position.

4. The apparatus as set forth in claim 3 wherein said endless conveyor means includes a plurality of transverse rows of apertures therethrough said upstream chamber along said transfer means having a length to communicate with substantially only a single row of apertures.