US3863902A

US3863902A - Flexible linkage wheel supported rotatable drum

Info

Publication number: US3863902A
Application number: US344531A
Authority: US
Inventors: Richard Edward O'brien; Arthur Raymond Simpson
Original assignee: Chicago Bridge and Iron Co
Current assignee: FIBRE MAKING PROCESSES Inc
Priority date: 1973-03-26
Filing date: 1973-03-26
Publication date: 1975-02-04
Anticipated expiration: 1992-02-04
Also published as: SE405330B; CA995291A; FI62718B; JPS538375B2; FI62718C; JPS49122061A; BR7400415D0

Abstract

A horizontally positioned rotatable cylindrical drum cradled in a pair of spaced-apart chains suspending said drum, and a plurality of wheels rotatably mounted on spaced-apart axles supported by each chain, said wheels rotatably supporting the drum. The rotating drum can be used to debark logs and mix and stir materials being treated.

Description

United States Patent [191 OBrien et al.

[451 Feb. 4, 1975 FLEXIBLE LINKAGE WHEEL SUPPORTED ROTATABLE DRUM [75] Inventors: Richard Edward OBrien, Geneva;

Arthur Raymond Simpson, Riverside, both of 111.

[73] Assignee: Chicago Bridge & Iron Company, Oak Brook, 11].

22 Filed: Mar. 26, 1973 21 Appl. No.: 344,531

[52] U.S. Cl 259/89, 241/178, 248/130, 308/203 [51] Int. Cl B0lf 9/02 [58] Field of Search 259/89, 90; 248/130; 241/178; 68/140; 51/164; 308/203, 204;

[56] References Cited UNITED STATES PATENTS 694,565 3/1902 Mason, Jr. 259/89 2,290,565 7/1942 Lagana 2,494,110 1/1950 Stiller 214/396 2,707,339 5/1955 Berge 259/90 X 2,793,920 5/1957 Haaff 308/204 3,216,666 11/1965 Svensson et a1. 259/89 X 3,507,469 4/1970 Vanderheyden 248/22 3,509,742 5/1970 Bauer 248/22 X 3,744,837 7/1973 Foster 294/74 FOREIGN PATENTS OR APPLICATIONS 769,894 6/1934 France 308/203 Primary ExaminerHarvey C. Hornsby Assistant Examiner-Alan Cantor Attorney, Agent, or Firm-Merriam, Marshall, Shapiro & Klose [57] ABSTRACT A horizontally positioned rotatable cylindrical drum cradled in a pair of spaced-apart chains suspending said drum, and a plurality of wheels rotatably mounted on spaced-apart axles supported by each chain, said wheels rotatably supporting the drum. The rotating drum can be used to debark logs and mix and stir materials being treated.

21 Claims, 20 Drawing Figures PATENTED 41% 3,863,902

SHEET 30F a PATENTED FEB 4191s SHEET 0F 8 NV QM RQN Qw WW I mum AWN QQN Mu QNN PATENTED 4|975 3,863,902

SHEET 8 OF 8 PATENTED FEB 41975 SHEET 7 OF 8 PATENTEU 4|975 3.863802 SHEET 80F 8 FLEXIBLE LINKAGE WHEEL SUPPORTED ROTATABLE DRUM This invention relates to industrial processing apparatus which employs a substantially horizontally positioned rotating drum. More particularly, this invention is concerned with improvements in such apparatus in which the drum rotates on wheels suspended by nontraveling chains.

Many industrial processes employ a rotating horizontal metal drum for processing heavy solid materials. The drum is usually rotatably supported in one of two ways. One way is to suspend the drum in a pair of spaced-apart endless chains. The endless chains run or travel on bar rings mounted on the drum at the same speed as the rotating drum. Such a system is disclosed in US. Pat. No. 3,269,438. Traveling chain supported drum apparatus withstands high impact loads and shock applied to the drum, very satisfactorily. The second usual way to support the drum is on trunnion wheels. See US. Pat. Nos. 3,262,477 3,701,487 and 3,709,268.

According to the present invention there is provided novel apparatus comprising a horizontally postioned rotatable cylindrical drum rotatably supported on wheels mounted on at least a pair of spaced-apart nontraveling chains suspending said drum in cradled arrangement with the chains in tension. Each chain has a plurality of wheels rotatably mounted on spacedapart axles supported by the chain. The wheels on each chain are placed in direct rolling contact with the drum surface itself or they are placed in contact with a track placed around the drum. The wheels are adapted to support the drum and rotate it in a direction counter to rotation of the wheels.

The chain used in the apparatus of this invention can be made of links and the ends of the links can be connected together by an axle. At least some of the wheels can be mounted on such axles. Alternatively, the ends of adjoining links can be connected together by a pivot pin and at least some of the wheels can be mounted on axles supported by the links between adjacent pivot pms.

An important feature of the subject invention is the use of chains which have two ends as distinguished from endless chains. Each chain in addition is nontraveling and has its ends connected to support means which is stationary or disp;aceable through a limited distance. The chain and wheels are unrestrained or unsupported apart from the drum and said support means. Neither the chain links nor the wheels have back-up supports to hold them in place. The chain is free to move lateral to the drum longitudinal horizontal axis. Ths support means can be provided with means for adjusting the effective length of the chain to thereby raise and lower the drum, or it can be provided with resilient means for absorbing tensile forces applied to the chains. The resilient means can be a spring or polymeric material like rubber or its equivalent. Fluid pressure means can be included as part of the chain support means for absorbing tensile forces applied to the chains. The fluid pressure means can constitute pneumatic or hydraulic means.

One, two or more wheels can be mounted on the same axle on the chain and some or all of the wheels on an axle can be mounted between or outside of adjacent link plates or elements.

The track means against which the wheels ride can constitute a single metal ring or a pair of metal rings mounted on the drum. The type of track to be used should be selected with due regard to the size and weight of the drum and the load to be placed therein, the number and size of the wheels to be used and whether the wheels will be flat rimmed or flange rimmed.

The invention will be described further in conjunction with the attached drawings in which:

FIG. I is a side elevational view of apparatus having a drum rotatably supported on wheels mounted on a pair of two-ended nontraveling chains;

FIG. 2 is a front elevational view of the apparatus of FIG. 1 taken along the line 2-2;

FIG. 3 is a partial sectional view of the apparatus of FIG. 1 taken along the line 3-3;

FIG. 4 is a plan view of apparatus essentially like that shown in F165. 1 and 2 but with hydraulic means supporting the chain ends;

FIG. 5 is a side elevational, partly schematic, view showing the drum of apparatus similar to that in FIG. I in tilted position;

FIG. 6 is an elevational view of the chain with wheels used to rotatably support the drum of FIGS. 1, 2 and FIG. 7 is a sectional view taken along the line of 77 of FIG. 6;

FIG. 8 is a sectional view through a two ring track with a two flanged wheel on each ring;

FIG. 9 is a sectional view through a single ring track showing two single flanged wheels on the same ring;

FIG 10 is a sectional view of a single ring track showing a single wheel with a flange on each edge of the rim;

FIG. 11 is a sectional view of a drum and single ring in which separated wheels ride on the drum surface with the ring provided as a wheel guide;

FIG. 12 is a sectional view of a single ring track having a central groove for a single wheel taken along the line12-I2 of FIG. 13;

FIG. 13 is a paln view of part of a chain showing a wheel mounted on an axle which also joins the ends of adjacent links together;

FIG. 14 is a plan view of part of a chain showing a wheel mounted on an axle between opposite link plates and between the ends of the link;

FIG. 15 is an elevational view, partially in section, of a coil spring support for the end of a chain;

FIG. 16 is an elevational view, partially in section, of a fluid support for the end of a chain;

FIG. 17 is a schematic end elevational view of a chain having supporting wheels for the drum mounted close together;

FIG. 18 is a view similar to FIG. 17 but with the wheels spaced farther apart;

FIG. 19 is a schematic end elevational view of a chain having supporting wheels for the drum mounted close together and with wheels located up to the drum equator to facilitate having the chain ends hang vertically from supporting beam and not contact the drum; and

FIG. 20 is a schematic end elevational view of a chain having wheels of progresively larger size from the upper part to the bottom part of the U-shaped suspended chain.

So far as is practical the same elements or parts which appear in the various drawings will be identified by the same numbers.

As shown in FIGS. 1 to 3, longitudinal horizontal structural beams and 16 are joined to the pair of lateral

horizontal beams

17 and 18, all of which comprises a base 10 which is secured to foundation 21. The base 10 serves to support one end of the drum 70. The other end of the drum is supported by a base 10A which is secured to foundation 21A. Base 10A consists of the same elements as base 10 so the elements have been given the same numbers. Two support means 25 and are mounted on base 10 and the two support means 45 and 55 are mounted on the base 10A. The support means 35 has a pair of spaced-apart upright beams 36 and 37 which are tilted outwardly from drum 70 as shown in FIGS. 2 and 3. Beam 38 is joined to the top of

beams

36 and 37.

Braces

39 and 40 serve to support the

beams

36 and 37 against tilting longitudinally. Each of the

beams

36 and 37 is outwardly braced by web and

flange weldments

41 and 42, and is inwardly braced by web and flange weldments 43 and 44 (FIG. 2). The other support means 25, 45 and are constructed in the same way as support means 35 so that the same parts are identifled by the same numbers in each support means in the drawings.

Drum 70 is suspended between support means 25, 35, 45 and 55 by means of two spaced-apart identical chains and 61. Chain 60 is joined at one end to rod 62 which extends through beam 38 and through coil spring 63. Retaining nut 64 holds rod 62 in place and thereby places spring 63 in compression. See FIG. 15. The other end of chain 60 is joined to rod 65 which extends through beam 38 and spring 66. Rod 65 is secured in place by nut 67, thus placing spring 66 in compression. Chain 61 is supported in the same way as chain 60 so the same parts are indentified with the same numbers.

Chain 60 (FIGS. 1, 2 and 6 is composed of a link 80, comprising a single link plate, and alternating links 81. Each link 81 is composed of two

link plates

82 and 83. Axle 84 passes through the end of link and the ends of

link plates

82 and 83 and joins them together. Each axle 84 supports a pair of

wheels

85, 86; 85A, 86A; 85B, 86B mounted outside of the links.

Wheels

85 and 86 are spaced closertogether than

wheels

85A and 86A as shown in FIGS. 6, and

wheels

85A and 86A are spaced closer together than

wheels

85B and 86B. The increased spacing between the wheels permits tilting of the drum by raising or lowering one end of the drum without having the chain bent or having the wheels jump the track on which they roll.

As shown in FIG. 1, each spaced-apart

track

90 and 90A is identical although they could be different with different shaped wheels on each chain. Track 90 is a single circular ring'mounted tightly on the outside of drum 70. Track 90 has a raised middle surface 91 and stepped-down side surfaces 92 and 93.

Wheels

85, 85A and 85B roll on surface 92 and

wheels

86, 86A and 86B ride on surface 93. The ring surfaces 92 and 93 are made wide enough to adequately support the wheels even when the drum is tilted.

The increased distance between

wheels

85B and 86B, and 85A and 86A, prevents the wheels from binding against the edge or side of raised central or middle surface 91. The dotted lines shown in FIG. 6 represent the position of track 90 when the drum is tilted, such as shown in FIG. 5, and the chain 60 is maintained vertical. The increased clearance between the wheels located towards the equator of the drum permits the tilting without putting a damaging strainon the wheels or the chain. Of course, if it is not desired to tilt the drum then the space between the wheels can be maintained uniform.

Rotation of drum 70 can be achieved by means of chain 95 which runs on ring sprocket 96 mounted circumferentially on the drum. Chain 95 is driven by sprocket 97 mounted on shaft 98 in operative connection with motor 99 through gear reducer 100. Sprocket 101 (Fig. 3) serves to control tension on chain 95. While one means of rotating drum 70 has been described, it is to be understood that other suitable means can also be used.

Replacement of the chains supporting drum 70 as shown in FIG. 2 can be readily achieved by releasing

nuts

64 and 67 and lowering the drum into contact with the top of members 43 in which the drum will rest in cradled position. The chains can then be completely removed and replaced or any of the wheels can be removed and be repaired or be replaced without dismantling the links.

The supporting means of FIGS. 1 and 2 permits ready removal of the drum 70 by lifting since there is no overhead obstruction.

With reference to Figure 4 it will be seen that the chain 60 is supported at both its ends, and that chain 61 is supported at one end, (although it could be supported at both ends) by fluid pressure means. Hydraulic cylinder 105 is placed in supporting communication with one end of chain 60 and hydraulic cylinder 106 is placed in supporting communication with the other end of chain 60. Hydraulic line 107 extends from pump 108 to cylinder 106 shown in greater detail in FIG. 16. Hydraulic line 109 extends from line 107 to valve 110 and line 111 extends from valve 110 to cylinder 105. Line 112 extends from pump 108 to valve 113 and line 114 extends from valve 113 to a hydraulic cylinder 115 in communication with one end of chain 61. With valve 110

closed cylinders

106 and 115 can be activated to raise and lower both ends of the drum at a uniform rate. However, to tilt the drum, such as to the position shown in FIG. 5 to facilitate emptying the contents therefrom, valve 113 can be closed and valve 110 can be opened to activate both

hydraulic cylinders

105 and 106 to raise or lower that end of the drum. Although perhaps only one of the

cylinders

105 and 106 need be activated to tilt the drum it is usually advisable to activate both of them to keep the wheels positioned symmetrically below the drum.

Tilting of drum 70 will generally necessitate the use of means to maintain the drum in a relatively fixed position relative to the supporting chains so that the drum does not become undesirably displaced longitudinally toward the low end of the tilted drum. To keep the drum in position and still permit it to rotate a suitable thrust means can be employed. One such system is shown in FIG. 5. Thrust ring is mounted to drum 70. Thrust

wheels

121 and 122 are mounted on axles supported in block 123. Each of the wheels rotatably presses against one side of thrust ring 120 to keep the drum in relatively fixed longitudinal position.

FIGS. 8 to 14 and 17 to 20 illustrate additional chain, track and wheel arrangements which can be used in the invention although it should be understood that the invention is not to be limited to the specifically illustrated embodiments of the invention.

In FIG. 8, a pair of spaced-apart rings 125 and 126 are welded to drum and together constitute a track.

Wheels

127 and 128, mounted on the same axle on a drum supporting chain, roll on rings and 126. Each of the wheels has a flange on each of its rim edges to keep the wheel on the ring.

FIG. 9 shows a track comprised of a flat ring 130 mounted on drum 70. A pair of wheels 131 and 132 is mounted on an axle supported by a chain. Each wheel has a flange on its outer rim edge. The flanges prevent the wheels from being moved laterally with respect to ring 130 during rotation of the drum.

FIG. 10 illustrates a track having a single flat ring 135 mounted on drum 70. A double-flanged wheel 136 supported by an axle in a chain rides on the ring. The flanges keep the wheel from moving off of the ring during rotation of the drum.

Another arrangement is shown in FIG. 11. Ring 138 is mounted on drum 70. However, the

wheels

85 and 86 run on the surface of drum 70 on each side of ring 138. Such an arrangement would not generally be use ful unless the drum surface was substantially smooth and free of troughs or corrugations. Even then it would not be used under normal circumstances where the drum was of large size and the load carried by the drum was relatively large.

FIGS. 12 and 13 show a further embodiment of chain, wheel and track apparatus which can be used. Chain 140 has alternating

links

141 and 142. Each link 141 has a pair of link plates 143 which are joined at their ends to an axle 144 on which wheel 145 is mounted between the link plates. Each link 142 has a pair of link plates 146 which are joined at their ends to axle 144. As shown in FIG. 12, drum 70 has a grooved ring 147 mounted thereon. Wheel 145 is adapted to roll in the groove in ring 147 and thereby lateral movement of the wheel with respect to the ring is prevented.

Still another chain-wheel arrangement is shown in FIG. 14. The chain is composed of alternating

links

150 and 151. Link 150 has a pair of spaced apart link plates 152 joined at each end to a pivot pin 153. Link 151 is composed of a pair of link plates 154 joined at their ends to pivot pins 153. Axle 155 is supported by the pair of link plates 154 between the ends of link 151. Wheel 156 is mounted on axle 155 and is adapted to roll in ring 147 as shown in FIG. 12. Of course, wheel 156 can be shaped differently as for example it can have one or two flanges as shown on the wheels in FIGS. 8 to 10.

It is considered more satisfactory to mount the wheels outside of the chain links as shown in FIGS. 7 and 9, than inside of the links as shown in FIGS. 13 and 14 for ease of installation and removal during repair operation since the links themselves need not necessarily be disassembled to remove the wheels.

The spacing of the wheels on the chain, and the size of the wheels, are to be determined in light of the size of the drum and its intended use. FIGS. 17 to 20 show some arrangements and positioning of the wheels which can be used.

The supporting arrangement of FIG. 17 employs seven single wheels, or seven dual wheels in side-byside relationship, as the main supporting structure for the drum 70. Side wheels 161 are positioned higher up the chain and serve to keep the chain links from rubbing against the drum.

The wheels 165 are positioned equidistant from each other on the chain shown in FIG. 18 to support drum 70.

FIG. 19 discloses drum 70 supported by a chain having a series of eleven wheels 166 equally spaced on a chain and with wheels 167 positioned about at the equator of the drum. The ends 168 and 169 of the chain are connected to supporting beam 170.

The supporting system shown in FIG. 20 could be used for heavy drums which handle heavy loads. The supporting system of FIG. 20 has been designed to have the lower central wheel 171 the largest with the adjoining wheels 172 slightly smaller. Wheels 173 are smaller than wheels 172, and wheels 174 are smaller than wheels 173.

All of the drum supporting systems described herein are operable without having the chain links rub against the drum or the wheel tracks on the drum.

Although a minimum of two spaced-apart U-shaped chain loops are used to support a drum, additional chain loops can be used to support a long drum, even a drum which is not dimensionally precise longitudinally or in circularity since the chains and supporting means for the chains provides a self-adjusting feature that achieves dimensional accommodation of the drum automatically, particularly when at least one end of each chain loop is supported by springs or a hydraulic support means which equalizes the load on each chain as the drum rotates.

The wheels are generally positioned on the chains so that the axis of the drum is parallel to the axes of the wheels. This avoids undue friction between the rotating drum and the wheels. However, it is sometimes advisable to position the drum so that its axis is non-parallel to the axes of the wheels, such as when it is desirable to tilt the drum to a position, such as shown in FIG. 5, to effect fast discharge of material from the drum. Fast empyting of logs debarked in the drum is desired in some pulp mills which switch from soft wood logs to hard wood logs during operation of the plant.

The axles or pins joining the chain links together, and the mounting of the wheel axles in the chain links, can be provided with enough clearance or play to permit automatic accommodation to any dimensional variations which may exist between the wheels and the drum, including variations between the mating faces of the wheels and tracks on the drum. In making such accommodations the wheel axes can vary from their normal position parallel to the drum axis.

The drum and wheel tracks are generally made of metal, and advisably are made of steel. The wheels are also advisably made of metal and preferably steel. However, other materials can be used for the drum, tracks and wheels if desired.

Apparatus provided by this invention is particularly useful in removing bark from logs to prepare them for conversion to pulp. For this reason logs are shown tumbling in the drum in FIG. 2. The rotating drum can also be used to mix and stir materials.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

What is claimed is:

1. Apparatus comprising:

a horizontally positioned rotatable cylindrical drum;

a pair of spaced-apart circular track means mounted circumferentially on the drum;

a pair of spaced-apart nontraveling chains suspending said drum in cradled arrangement with the chains in tension;

each chain having two ends, with the ends of each chain connected to a support means;

a plurality of wheels rotatably mounted on spacedapart axles supported by each chain, said wheels rotatably contacting one of the track means and thereby rotatably supporting the drum;

the axis of the drum being substantially parallel to the axes of the wheels;

said chain and wheels being unrestrained apart form the drum and said support means and;

power drive means connected to said drum to rotate said drum while being cradled between said chains.

2. Apparatus according to claim 1 in which at least some of the support means include means for adjusting the effective length of the chain which it supports.

3. Apparatus according to claim 1 in which at least some of the support means include resilient means for absorbing tensile forces applied to the chains.

4. Apparatus according to claim 3 in which the resilient means is rubber.

5. Apparatus according to claim 1 in which at least some of the support means include fluid pressure means for absorbing tensile forces applied to the chains.

6. Apparatus according to claim 5 in which the fluid pressure means is a pneumatic means.

7. Apparatus according to claim 5 in which the fluid pressure means is a hydraulic means.

8. Apparatus according to claim 1 in which each chain is made of links, the ends of adjoining links are connected together by an axle, and at least some of the wheels are mounted on such axles, said wheels being adapted so that the drum is rotatably supported by the wheels contacting the track means to rotate in a direction counter to rotation of the wheels.

9. Apparatus according to claim 8 in which a substantial number of axles support two wheels and the ends of the links joined to an axle are joined thereto between the two wheels.

10. Apparatus according to claim 9 in which the two wheels on the same axle are positioned to ride on one of the track means mounted on the drum.

11. apparatus according to claim 10 in which the track means is a single metal ring mounted on the drum.

12. Apparatus according to claim 10 in which the track means is a pair of metal rings mounted on the drum.

13. Apparatus according to claim 8 in which some links comprise a pair of link plates and a number of such links have the axle mounted wheels between the link plates.

14. Apparatus according to claim 1 in which each track means is a single metal ring mounted on the drum.

15. Apparatus according to claim 1 in which each track means is a pair of metal rings mounted on the drum.

16. Apparatus comprising:

a pair of chain with each chain having two ends;

the two ends of each chain being connected to support means to form a substantially U-shaped loop and with each loop being spaced from the other loop;

at least one end of one chain being adjustable with respect to the support means to vary the height of the U-shaped chain loop;

each chain having a plurality of wheels rotatably mounted on spaced-apart axles supported by each chain;

an essentially horizontally positioned rotatable cylindrical drum cradled in the U-shaped chain loops, with the chains in tension;

a paii'of spaced-apart circular track means mounted circumferentially on lthe drum with the wheels of each chain being in drum supporting rotatable contact with a track means;

said chain and wheels being unrestrained except by the drum and said support means; and

power drive means to rotate the drum while being cradled between said chains.

17. Apparatus according to claim. 16 in which the axis of the drum is parallel to the axes of the wheels.

18. Apparatus according to claim 16 in which the axes of the wheels are nonparallel to the drum axis.

19. Apparatus according to claim 16 in which the chain is made of links and the links are maintained out of contact with the drum.

20. Apparatus according to claim 16 in which the chains are made of links and the links are joined together with sufficient clearance to permit accommodation of dimensional variations between the wheels and the drum.

21. Apparatus comprising:

a horizontally positioned rotatable cylindrical drum;

a pair of spaced-apart nontraveling chains connected to a support means suspending the chains in slinglike contour with said drum suspended by the chains in cradled arrangement with the chains in tension;

a plurality of wheels rotatably mounted on spacedapart axles supported by each chain, said wheels rotatably contacting one track means and thereby rotatably supporting the drum;

the axis of the drum being substantially parallel to the axes of the wheels;

22 35 UNITED sures PATENT OFFICE "1 I I i CERTEFELATE G1 CORRECHON Patent No. 863r902 Dated ry 4 1975 Inventm-(s) Richard OBrien et al.

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 2% after 3,262,477" insert a comma lg' ne 24-, cmcf postioned" to --positioned-; line 48, change "disp;aceable" to ---displaceable-; line 54, change "Ths" to -The--; column 2, line 41, change "paln" to plan--; l ine 6 Cl, after "from" insert -a-; column 7, line 15, change "means and;" to means; and--; line 48, change "a'qaparatus to --Apparatus---; column 8, line 2? change "lthe" to --the; line 51, after "one" insert -of the--.

Signed and sealed this 15th day of April 1975.

Art-resting Q'fic r and Trademarks L. Page 1 of 1 J

Claims

1. Apparatus comprising: a horizontally positioned rotatable cylindrical drum; a pair of spaced-apart circular track means mounted circumferentially on the drum; a pair of spaced-apart nontraveling chains suspending said drum in cradled arrangement with the chains in tension; each chain having two ends, with the ends of each chain connected to a support means; a plurality of wheels rotatably mounted on spaced-apart axles supported by each chain, said wheels rotatably contacting one of the track means and thereby rotatably supporting the drum; the axis of the drum being substantially parallel to the axes of the wheels; said chain and wheels being unrestrained apart form the drum and said support means and; power drive means connected to said drum to rotate said drum while being cradled between said chains.

4. Apparatus according to claim 3 in which the resilient means is rubber.

16. Apparatus compriSing: a pair of chain with each chain having two ends; the two ends of each chain being connected to support means to form a substantially U-shaped loop and with each loop being spaced from the other loop; at least one end of one chain being adjustable with respect to the support means to vary the height of the U-shaped chain loop; each chain having a plurality of wheels rotatably mounted on spaced-apart axles supported by each chain; an essentially horizontally positioned rotatable cylindrical drum cradled in the U-shaped chain loops, with the chains in tension; a pair of spaced-apart circular track means mounted circumferentially on lthe drum with the wheels of each chain being in drum supporting rotatable contact with a track means; said chain and wheels being unrestrained except by the drum and said support means; and power drive means to rotate the drum while being cradled between said chains.

17. Apparatus according to claim 16 in which the axis of the drum is parallel to the axes of the wheels.

21. Apparatus comprising: a horizontally positioned rotatable cylindrical drum; a pair of spaced-apart circular track means mounted circumferentially on the drum; a pair of spaced-apart nontraveling chains connected to a support means suspending the chains in sling-like contour with said drum suspended by the chains in cradled arrangement with the chains in tension; a plurality of wheels rotatably mounted on spaced-apart axles supported by each chain, said wheels rotatably contacting one track means and thereby rotatably supporting the drum; the axis of the drum being substantially parallel to the axes of the wheels; said chain and wheels being unrestrained except by the drum and said support means; and power drive means connected to said drum to rotate said drum while being cradled between said chains.