US1958341A - Roller conveyer - Google Patents

Description

May 8, 1934- A. o. HURXTHAL ROLLER CONVEYER Filed April 22. 1931 5 Sheets- Sh eet l mi@ m Si@ v @es .w

'm im' LQ@ .STS mi w s@ mi @si @s 'w May 8, 1934. A. o. HURXTHAL ROLLER CONVEYER Filed April 22. 1931 5 Sheets-Sheet 2 May 8, 1934- A. o. HURXTHAI` 1,958,341

ROLLER CONVEYER Filed April 22. 1931 5 Sheets-Sheet 3 May 8, 1934. A. o. HURXTHAL ROLLER CONVEYER Filed April 22. 1931 5 Sheets-Sheet 4 mv l May 8, 1934. A. o. HURXTHAL ROLLER CONVEYER Filed April 22. 1931 5 Sheets-Sheet 5 UNITE STATES PATENT OFFICE ROLLER CONVEYER Alpheus 0. Hurxthal, Philadelphia, Pa., assigner to Proctor & Schwartz, Incorporated, Philadelphia, Pa., a corporation of Pennsylvania Application April 22, 1931, Serial No. 532,093 8 Claims. (Cl. 198-165) This invention relates to conveyers, and parplates, being turned end for end in passing from ticularly to a new, useful and novel combination one horizontal level to another, as the endless of elements that is especially adapted for use in belts are operated. advancing sheet or web materials such as veneer, If it is desired to dry, for example, four or more e wall board, or cloth, etc. through the drying runs of material at one time, with all of the runs chamber of a suitable conditioning apparatus. moving in the same direction, which requires the In driers for sheet material, such as veneer, two use of a separate conveying unit for each run, distinct types of conveying apparatus have been the drier, of necessity, attains such a height that A commonly employed, one of which comprises a the sheets cannot be conveniently fed to the le conveying unit consisting of two endless belts uppermost units or conveniently taken from such operating one directly on top of the other, with upper units, due to the height of the upper conthe sheet material disposed between the adjaveying units from the floor on which the drier is cently disposed runs of the two belts. mounted.

v In a unit of this kind the bottom belt functions The roller type of conveying unit obviously l as a carrier unit, for advancing the material may be made of a lesser vertical overall dimen- 70 through the drier, while the top belt serves as a sion than the belt type of conveying unit, consepressure unit for holding the material down On quently the roller type of conveying unit is more the bottom belt, for the purpose of reducing the adapted for use in 11111113-11, (mers, as a rela- Weping Of the Sheets t0 e minimum during the tively large number of the roller type conveying 2o drying operation and thereby causing the sheets units may be employed, one above the other,

tc be dried in a substantially at Condition without increasing the height of the drier to the The second of these Well-kIlOWIl typesl 0f Conf extent that the upper units cannot be convenveying apparatus comprises a COYlVeYlng mt iently fed with the sheets to be dried.

which consists of two superposed series of rollers The Toner type of Conveying mit however, has

operating With the T0115 0f the top Series arranged certain inherent and undesirable qualities one respectively above and substantially in vertical of which resides in the fact that the Sheets in alignment Witt.1 tti@ T0115 0f the bottom SUES the passing from one vertically aligned pair of rollers top T0115 llIlCtlOnmg as the Pressure umt to hld to the next successive pair, longitudinally of the the sheets down fiat on the lower rolls which Conveying unit, ae apt to Cun to Such an extent Y3o function as the carrying unit, whereby the sheets up O1. down from the normal horizontal plane; Will be heid between the tWO 59H65 of rous-9nd of travel of the sheets, as to prevent the leading advanced by the rolls as the rolls rotate in unison. edge of the sheet from Coming into the bite of The dl'lers m Whlch these Comfeymg umts are the said succeeding pair of rolls, consequently employed are usually adapted f m drymg a num' the sheet will foul the upper or lower rolls of be? 0f runs 0f matenal at' one mme by arrangmg the conveying unit as the case may be and beseveral complete conveying units in horizontal come so jammed nl the apparatus as t6 necess Superposed relamon to eachpther tate the shutting down of the drier until the jam The belt type of conveying um; 1S generally can be Cleared considered to be the more ideal or conveying f Y are positively held at all times between the upper bm f h t n 1 f th d ie d b run of the bottom boit and the lower run of the 1 Y 0 ab e ,n e ,01 0 e e Y as 1S Cause Y top belt. These endless belts usually consist of @he '310%' posmonutg Qf the Superpsefi Convey* side chains suitably connected by transversely mg ,umbs the, heat 71mm the dlymg @hamper adding materially to the difficulty of clearing extendin girts which also function to support 1 I l *o the endsgof relatively stiff rods, screens or perthe apparatus Wfleli Such fouillis of the rolls romeu platos that extend iongitudinaiiy of the takes place.

toits and substantiaiiy parallel to the Side chains, In Some instances the pairs of vertically aligned for Suppgrting and holding down the sheets inrolls have been placed relatively close together Serted between the two belts, in order to reduce the possibilities of the sheets 105 Each of the conveying units of this particular fouling in the successive rolls. Such close posiconstruction requires a relatively large amount tioning of the rolls materially adds to the eX- of space, vertically, as the side chains of the belts pense of building and maintaining the drier and must pass around sprockets of such diameters as adds to the inaccessibilty should fouling of the will permit of the rods, screens or perforated rolls occur, and furthermore the close positionlo CFI ing of the pairs of rollers does not entirely eliminate the fouling of the rolls.

Attempts have been made to combine certain features of these two well-known types of conveying units with a view of producing a drier having such a height, for a given number of runs, that the feeding of the upper units may be conveniently carried on. Such units have been made by combining a conveying belt of the endless type, for supporting the sheet material, and a series of rolls disposed above the carrying belt, for holding the sheet material down thereon.

While this construction permits the building of the drier having a height relatively less than the height of a drier using endless belt units exclusively but greater than one using roller units exclusively, and while this combination eliminates the possibilities of fouling of the rolls by do. nward bending of the sheets, such a conveying unit, however, is still open to the possibilities of fouling by an upward bending of the sheets, as the sheets are carried along from one roller to the next successive roller longitudinally of the drier.

The primary object .of the present invention is to construct a unit comprising a series of rolls spaced at a greater distance apart than has been possible or practical heretofore and to combine with these relatively Widely spaced rollers means for guiding the sheets from one roll to the next successive roll, the guides being arranged in such a manner with respect to the rolls to prevent fouling of the rolls, thereby eliminating the possibilities of the apparatus becoming jammed in the manner above noted.

A unit made in accordance with the principles of this invention is adapted for use as a carrying unit, as a pressure unit, or for use in superposed pairs to form a complete conveying' unit including a carrying unit and a pressure unit, as will be hereinafter fully disclosed.

Other combinations, modiiications, advantages, and the detailed construction of the device forining the subject of the present invention will be fully disclosed hereinafter, reference being had to the accompanying drawings, cf which:

Fig. 1 is a diagrammatic sectional elevation illustrating the invention adapted for use as a material-carrying unit, in a multi-run drier, without the use of means for holding the material down on the carrying unit;

Fig. 2 is a View similar to Fig. 1, but showing a plurality of conveying units disposed in superposed relation and wherein each conveying unit comprises a pair of superposed series of rollers, one series of rollers functioning as a carrying unit and the other series of rollers functioning as the pressure unit, and wherein. sheet-guiding means is provided between the rollers of each of the superposed series of rollers;

Fig. 3 is a view similar to Fig. l, but showing the carrying unit in the form of an endless belt and the pressure unit as a series of rollers with sheet-guiding means extending from roller to roller;

Fig. 4 is a detail illustrating one means for driving the rollers of the units shown in Fig. 1;

Fig. 5 is a fragmentary longitudinal sectional elevation of one of the conveying units illustrated in Fig. 2 and drawn to an enlarged scale;

Fig. 6 is a fragmentary plan view of one of the conveying units shown in Fig. 3;

Fig. 7 is a longitudinal sectional elevation taken on the line 7 7, Fig. 6;

Fig. 8 is a transverse sectional elevation taken on the line 8-8, Fig. 7;

Fig. 9 is a longitudinal sectional elevation through a conveying unit constituting a modincation of the invention;

Fig. l is a fragmentary plan View of the apparatus shown in Fig. 9;

Fig. 11 is a View similar to 5, but showing a unit having an alternative arrangement of rollers and guides;

Fig. 12 is a View similar to Fig. 11, but showing the combination of guides and rollers being used as a carrying unit without a pressure unit;

Fig. 13 is a fragmentary plan view partly in section and illustrating one means for supporting the rollers when the apparatus is employed as a pressure unit;

Fig. 14 is a sectional elevation taken on the line 1li-14, Fig. 13;

Fig. l is a sectional line 15 15, Fig. 13;

. Figs. l5 vand 17 are respectively a sectional elevation and plan of one form of means for anchoring the pressure unit shown in Figs. 2 and 3 against longitudinal movement by the underlying carrying unit;

Fig. 18 is a fragmentasy plan view of another arrangement of rollers and guides;

Fig. is is Va side elevation of the apparatus shown in Fig. 18; and

Figs. 23 and 21 illustrate a method of driving th lndiviclual rollers of a unit made in accordance with. the principles of the present invention.

Fig. 1 of the drawings diagrammatioally illustrates a drier comprising a top 1, side walls 2 and end walls 3 and 4 respectively, which provide an inclosurc in the form of a drying chamber 5. Within the drying chamber 5 is a plurality of units which are respectively made in accordance with the principles of the present invention. The units l0 are disposed in horizontal planes respectively, in superposed, spaced, and substantially parallel relation with respect to each other.

Each of the units 10 comprises a series of rollers 11 disposed in relatively wide laterally spaced relation with respect to each other, longitudinally oi the drying chamber 5. Each of the rollers 1l is of the general character shown in Figs. 6 and 13, wherein the peripheral surface 12 of each roller has a series of circumferential grooves 13 formed therein, the groves of each roller being in spaced relation with respect to each other across the peripheral face of the roller. The rollers are so arranged that the grooves 13 of the successive rollers 11 are in substantial alignment with each other longitudinally of the series of rollers.

Seatedin the grooves 13 of the rollers ,11 and extending between each laterally spaced pair of said rollers is a series of sheet-guiding elements i5 which, in the preferred forms of the invention, are composed of endless belts formed of circular spirally coiled springs, the convolutions of which normally lie in close abutting relation to each other.

The rollers l1 are provided at their opposite ends with axially aligned trunnions 14, 14, which are adapted to be rotatably mounted in suitably spaced bearings, whereby the rollers are maintained in spaced relation to each other.

The spring belts are of such a diameter that, when the belts are seated in the bases of the grooves 13 of the rollers 11 the outer faces of the spring belts 15 lie iiush with or a slight diselevation taken on the tance below the peripheral surfaces 12, 12 of the rollers 11, l1 respectively.

The resilient nature of the spring belts 15 obviates the necessity of providing any slack adjusters for the individual belts, as the belts, when in position on the spaced rollers, are stretched to some extent and are, therefore, maintained in a taut state, between the rollers around which they pass, by their own inherent tendency to contract to their normal state.

In Fig. 1 of the drawings, the units 10, which comprise the above noted combination of rollers 11 and guides 15, are employed as material-carrying units without the use of any means for holding the material down. In this application of the units 10 the trunnions 14 of the rollers 11 may be mounted in suitable bearings formed in or carried by the side walls 2 or other framework or the drier and the rollers of the several units may be rotated in unison by any suitable means desired; for example, the trunnions of one or more of the rollers of each unit 10 may be extended beyond the side walls 2 of the drying chamber and provided with a suitable pulley or sprocket wheel 16, around which may pass a suitable belt or sprocket chain 17 which, intermediate the superposed units 1c, may pass around suitable idlers 18 and around other suitably placed idlers 19 whereby the driving element 17, moving in the direction of the arrow in Fig. 1, will rotate the rollers of all the superposed units 10 in the same direction and at the same rate of speed.

The laterally spaced rollers 11 of each unit 10, due to the plurality ci resilient guide belts 15 passing around the rollers, in the manner illustrated in Fig. 6, will cause all the rollers of each unit to be driven in a like manner, in the same direction and at the same rate of speed, whereby any sheets or other material placed on top of the rollers 11 or" any oi the units 1G will be advanced through the drying chamber; for example, from the left to the right, as viewed in Fig. 1, with the belts 15 functioning to guide the material from the crest of one roll 11 to the crest of the next successive roll 11.

As shown in Figs. 1 and 2, longitudinally spaced vertically aligned rows of the rollers 11 are driven in unison by the driving elements 17 17 respectively, as in Fig. 1, or by gear trains including gears 16a, 18a, as shown in Fig. 2, and the several rolls of each unit are driven in unison through the belts 15, 15, but obviously each roll of each unit, or any desired number of the rolls of each unit may be provided with suitable driving means in addition to the belts 15, 15, for rotating the rolls of each unit in unison. For example, each lower roll 11 may be provided with a sprocket 19, see Figs. 20 and 21, and the various sprockets may be operatively connected by a common drive chain 19a, which when the roll 1l, driven by the element 17, is rotated all the other rolls of the carrying unit will be correspondingly rotated. Each lower roll 11 may be provided with a gear 19h adapted to mesh with a corresponding gear 19e on the vertically aligned upper roll 11, whereby the upper rolls will be driven in unison with the lower rolls.

Power may be applied to the driving element 17 through the medium of a pulley, sprocket or gear wheel 20 mounted on one oi the roller trunnions 14 and connected to any suitable source of power, not shown, or the driving wheels 16 may be separately driven for the purpose of driving the rollers 11 of the respective series of rollers at diierent speeds, to advance the runs of material carried by the respective series of rollers, at diierent lineal speeds.

In Fig. 2, a plurality of conveying units 20 are shown in superposed relation to each other. Each of these units 20 comprises one of the units 10 which functions as a material-carrying unit in the same manner as the carrying units 10 shown in Fig. 1. Superposed upon each of the carrying units 10 is a corresponding unit functioning as a hold-down unit as indicated at 30. Each of the hold-down units 30 is identied in structure with the carrying units l0 with which they are associated, with the exception of the mountings for the trunnions 14, 14 of the rollers 11.

In instances where combinations of rollers 11 and intermediate sheet-guiding means 15, which forms the subject o1" this invention, are used as hold-down units as indicated at 30, 30 in Figs. 2 and 3, for example, the trunnions 14 or the rollers 11 are mounted in the manner illustrated in Fig. 6, wherein these trunnions 14 of the rolls 11 are rotatably mounted in bushings 31 which, in addition to providing suitable bearings for the trunnions, function as pintles for, and 100 at the junction of, side links 32, 32, which function to maintain the rollers 11, 1l in spaced relation with respect to each other, against the tension of the coiled spring belts 15, 15 extending between and around the spaced rollers 11.

The body portions of the links 32, as shown in Figs. 6 and 13, are substantially aligned with respect to each other and one end of each link 32 is provided with an oiset portion 34 in which one end of the pintle bushing 31 is mounted. Ad- 110 jacent to, and spaced laterally from, the oiset 34, each oi' the links 32 is provided with an extension bracket 35 in which the opposite end of the pintle bushing 31 is mounted. The opposite straight end 33 of each link 32 is rotatably 115 mounted on the pintle bushing 31 of the next link, and lies between the laterally spaced parts 34 and 35 thereof.

The trunnions 14 of the rollers 11 are permitted free rotation within the pintle bushings 120 31 and the straight ends of the links 32 are permitted free pivotal movement around the outside o1 the pintle bushings 31, which are held rigidly in the bifurcated end of the next adjacently disposed link.

Rotation of the pintle bushing 31 with respect to the bifurcated end of each of the links 32 is prevented by segmental lugs 36 formed in the ends of the oiset 34 and extension 35 of the link, which enter segmental cavities 37 formed 13() in the bushing 31, as clearly shown in Fig. 14. This construction relieves the trunnions 14 of the side thrust produced by the links 32 in maintaining the rollers in spaced relation under the tension of the spring belts 15, 15, and also provides for removal of the trunnions from the bushings without disassembling the links 32, 32.

The hold-down units 30 are adapted to rest of their own weight on the underlying carrying units respectively or on sheets of material being carried by said carrying units, the pivotal connections between the links 32, 32 permitting each hold-down unit 30 to accommodate itself to any variations in the plane of the carrying unit, at all times, so that the sheet material will be held 145 down at all points by the hold-down unit 30.

The construction of the hold-down unit 3) permits of its easy removal from the drying chamber at any time should such removal be desired or become necessary. To provide for 150 such removal the entire hold-down unit 30 is adapted to be anchored at its end lying adjacent the feed end o the drying chamber in which the unit is located, the whole of the holddown unit riding loosely on the carrying unit and being held against transverse displacement with respect to the carrying unit by means of lugs 36, which are secured to and located adjacent the bifurcated ends of the links 32, in the present instance, with the outer edges 37 of the lugs lying adjacent longitudinally extending guide rails 38, as clearly shown in Figs. 6 and 8.

Excessive vertical movement of the hold-down unit 30 is prevented by means oi angle or other limiting bars 39 which extend longitudinally of the chamber 1, said limiting bars being spaced above and in substantially parallel relation to the guide bars or rails 38, as shown in Fig. 8.

Any suitable means may be provided for anchoring the one end of the carrying unit 30 in the drying chamber; for example, the spacing members at the opposite sides of the unit may be provided, at the anchoring end of the unit with suitable hooks or eyes, such as illustrated at 40, in Figs. 16 and 17, for engagement with a transversely extending anchor bar, or studs 41, disposed adjacent the end wall 3 of the drying chamber and extending inwardly of the chamber 1 from the oppositely disposed sides of the chamber 1, respectively.

In order to remove the hold-down unit 30 from the drying chamber the anchoring means at the feed end oi the chamber is released. and the unit 30 is permitted to rest on, and to be conveyed through the drying chamber by, the underlying carrying unit, whereby the hold-down unit will be passed out of the drying chamber through the opening 42 formed in the end wall 4 at the discharge end of the chamber 5, through which the material normally is carried and discharged by the carrying unit.

1n order to reinsert the conveying unit 3G, one end of the hold-down unit 30 is placed on the carrying unit at the feed end of the chamber 5 and permitted to pass through the feed opening 4A formed in the end wall 3 of the chamber, through which the material is normally fed to the drying chamber. The hold-down unit 30 is then fed into and is carried through the chamber 5, by the underlying carrying unit, until the opposite end of the hold-down unit lies within the chamber 5, whereupon the hooks or other anchoring means 40 are attached to the stationary anchoring elements 41, thereby preventing further longitudinal movement of the hold-down unit 30 through the drying chamber.

The rolls 11 of the hold-down unit 30, at such time, are in the correct position to cc-operate with the underlying carrying unit to assist in advancing the sheet material through the drying chamber and to hold the said material down rmly on the underlying carrying unit.

Figs. 3, 6, 7 and 8 illustrate the hold-down unit 30 in combination with the usual form of endless belt-carrying unit employed commonly for advancing the material through the drying chamber. This form of carrying unit comprises the usual side chains 50 connected by the transversely extending girts 51 and pro-vided with rollers 52 adapted to ride on rails 53 secured to the side walls and extending longitudinally of the drying chamber 1.

Extending longitudinally of the belt between the relatively spaced girts 5l, is a series of laterally spaced and relatively still" rods 54 having hooked ends 55 which engage the girts 51, 51, the lateral spacing of the supporting rods 54 on the girts 51 being maintained by the usual girt aprons 55 having openings 57 through which the hooked ends 55 or" the rods extend when hooked onto the girts 51, as clearly shown in Fig. 8.

Figs. 9 and 10 illustrate a modification of the invention wherein a series or" rolls 11 are maintained in laterally spaced relation to each other to function as a carrying unit and wherein the belts 15 are replaced by longitudinally extending rods 15a, which respectively rest in substantially aligned grooves 13 of the spaced rolls 11, the rods 15a functioning as guides for the material :l: as it advances from the crest of one roll l1 to the crest o the next relatively spaced roll 11, the rods 15a being anchored to the end wall 3 of the drying chamber 5 in any suitable manner, such, for example, as illustrated in Fig. 9.

The guide means of the superposed hold-down iuiit 35d, in this instance, comprise short rods having hooked ends 15o which embrace and ride freely in the bases of the grooves 13 of the rollers 11 of the hold-down unit 30a, in the manner illustrated in Fig. 9, the rods 15b in this case preventing upward curling of the forward ends of the sheets .r as they are advanced by rotation oi the rollers 11 and the rods 15a of the underlying carrying unit preventing downward curling of the forward edges of the sheets as they are advanced through the drying chamber.

12 illustrates a unit lud comprising a combination wherein guide belts 15d are stretched between and around two widely spaced rollers 11a, 11a of a series o1" rollers, with a third roll 11b of the series lying intermediate the two rolls around which the ends of the belts 15d pass, the intermediate roll 11b being freely rotatable with the belts 15d merely resting in the grooves 13 oi the roll 11b, as shown.

Fig. 11 shows two of the units 10d, disposed in superposed relation to each other with the lowerrncst unit functioning as the carrying unit the upper unit functioning as the hold-down unit. 1n this instance, as in Fig. 12, the coiled spring belts 15d pass around one roller, rest in the grooves ci the next successive roll, and pass around a third successively disposed roll. Thus, it will be seen that in place of the belts 15d passing around successively arranged pairs of rollers 11a these belts may be of such length as to include any desired number of the rollers, while resting in the grooves of intermediately placed rollers.

1n Figs. 18 and 19, a modication is shown whereLn the belts 15e pass around and rest, for example, in one roller groove 13 disposed in one vertical plane extending longitudinally of the drying chamber while the opposite end of such belt passes around and rests in a groove 13, in the next successive roller, that is disposed in a vertical plane laterally spaced with respect to the plane in which the first said end of the belt is located.

Thus, the belts 15a, in place or" traveling in a plane parallel to the center line of the drying chamber, move in planes disposed at angles with respect to the longitudinal center line y, y of the drying chamber, as shown in Fig. 18, the belts 15e at one side of the center line y, y traveling forward and toward one of the side walls of the drying chamber while the belts 15e at the opposite side of the center line y, y travel forward ico and toward the opposite wall of the drying chamber.

rrhis arrangement is particularly adapted for use in the drying of more or less iiimsy material, such as lighter Weight papers, or cloths, or other webs, the material x1, as shown in Fig. 19, being gripped between the belts 15e of the lower can rying unit and the correspondingly arranged belts 15e oi the upper hold-down unit. As the rolls ll rotate to advance the material longitudinally through the drying chamber the belts 15e, 15e moving forward at opposite angles with respect to the center line y, y of the drying chambei tend to spread the material transversely, to work out any wrinkles that may be in the material, whereby the material will be delivered from the drying chamber in a flat smooth state, devoid oi wrinkles.

As shown in Fig. 13, the rolls 1l may be made hollow to reduce their weight, by the use of a tube 60, and rigidly securing in its opposite heads 61, 61 in which the trunnions le, 14 are respectively secured.

In the construction, as above noted, power may be applied to any desired number of the rollers 11 and the coiled spring belts 15 in passing around the driven rolls and around the successively spaced rolls, will function to drive these rolls to which power is not otherwise applied.

The inherently resilient nature of the belts obviates the necessity for providing any slack adjusting means for the belts, such as would be necessary if other non-resilient belts were employed.

The temper of the spring belts is such that the belts will readily withstand the heat within the drying chamber, without losing their inherent resiliency, they are therefore, not aiected by the heat within the drying chamber and consequently will maintain a taut state, and will adjust themselves to any variations in the spacing or" the rollers 1l, such as may be caused by eX- pansion and contraction of the side links 32 or other means provided for maintaining the rollers 1l in spaced relation to each other.

From the above, it will be obvious that the combination of laterally spaced grooved rollers with resilient belts seated in the grooves and acting as guides for the material in its passage from roll to roll is adaptable for wide and varied usages and that the invention is particularly adapted to veneer and similar driers employing the roller type conveyor units, whereby a large number of runs of material may be passed through the drier in one direction, at one time, at the same or relatively different lineal speeds, without the drier attaining an inconvenient height for handling the uppermost runs of material and at the same time eliminating the possibilities of the material fouling the rolls or otherwise causing any interruption of the continuous drying process.

I claim:

1. In a conveying unit, the combination of a carrying unit, a hold-down unit resting on said carrying unit, and readily releasable anchoring means at one end of said hold-down unit for securing said hold-down unit against longitudinal movement by said carrying unit and for permitting said hold-down unit to be bodily advanced by said carrying unit upon release of said anchoring means.

2. In a conveying unit, the combination of a series of laterally spaced rollers, trunnions extending outwardly from the opposite ends of thc rollers respectively, side links extending rigidly between the rollers along the opposite sides of the series, and pivotal elements for said links comprising bushings mounted in the ends of adjoining links upon which at least one of said links swings, said bushings affording bearings for rotatably mounting the roller trunnions.

3. In a conveying unit, the combination of a series of laterally spaced rollers, trunnions eX- tending outwardly from the opposite ends of the rollers respectively, side links extending rigidly between the rollers along the opposite sides of the series, pivotal elements for said links comprising bushings mounted in the ends of adjoining links upon which at least one of said links swings, said bushings affording bearings for rotatably mounting the roller trunnions, and means for securing each bushing in one of the links pivotally connected thereby against relative rotation between the bushing and said link.

4. In a conveying unit, the combination of a carrying unit and a free riding hold-down unit superposed from said carrying unit, said holddown unit comprising a plurality of laterally spaced rollers, resilient belts passing around relatively spaced pairs of said rollers, rigid links extending longitudinally alo-nfT the side edges of the hold-down unit and pivotally connecting successive rollers of the series for maintaining said lateral spacing of the rollers against inherent cent1-active tendencies or" the belts and providing for longitudinal flexibility in said hold-down unit, means for anchoring one end of said hold-down unit against longitudinal movement by said carrying unit, and means for maintaining said hold-down unit against transverse displacement with respect to said carrying unit.

5. The combination, in a drier for sheet materials, oi a plurality of superposed conveying Units each of which comprises a carrying unit and a hold-down unit bodily resting thereon, each hold-down unit comprising a series of laterally spaced circumferentially grooved rollers and a series of endless coiled spring belts seated in the grooves and bridging the spaces between the rollers of the respective series.

6. The combination, in a drier for sheet materials, of a plurality of superposed conveying units each of which comprises a carrying unit adapted t0 advance material through the drier from end to end thereof and a co-operating hold-down unit adapted to rest bodily and ride freely on said carrying unit for holding the material down as the material is advanced through the drier by the carrying unit, and means for releasably anchoring the hold-down unit in the drier against bodily movement through the drier by the carrying unit, whereby the hold-down unit of any of said superposed conveying units may be withdrawn and carried out of the drier from between the adjacently disposed conveying units by its co-operating material-carrying unit upon release of said anchoring means.

7. In a conveying unit, the combination of a series of rollers disposed in spaced parallel relation longitudinally of the unit, each roller having a series of circumferential grooves spaced transversely of the unit, and endless belts seated at their opposite ends respectively in relatively transversely spaced grooves of succeeding rollers, with the belts adjacent one side of the unit extending at an angle toward said side and the belts adjacent the opposite side of the unit eX- tending at an angle toward said opposite side oi the unit to spread material carried by the CFI seated at their opposite ends respectively in relatively transversely spaced grooves of succeeding rollers, with the belts adjacent one side of the unit extending at an angle toward said side and the belts adjacent the opposite side of the unit extending at an angle toward said opposite side of the unit, whereby the interposed material will be longitudinally advanced and transversely spread at the same time.

ALPHEUS O. HURXTHAL.

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