US2068302A

US2068302A - Molding apparatus

Info

Publication number: US2068302A
Application number: US40836A
Authority: US
Inventors: Edwin F Nickol
Original assignee: EDWIN F NICKOL Inc
Current assignee: EDWIN F NICKOL Inc
Priority date: 1935-09-16
Filing date: 1935-09-16
Publication date: 1937-01-19
Anticipated expiration: 1954-01-19

Description

Jan. 19, 1937. E. F. NICKOL MOLDING APPARATUS Filed Sept. 16, 1935 3 Sheets-Sheet 1 EcMinIZ'JVickal Jan. 19, 1937.

F. NICKOL MOLDING APPARATUS Filed Sept. 16, 1955 3 Sheets-Sheet 2 .Zi'dwir FNiclaoZ m V E i Q A E. F. NICKOL MOLDING APPARATUS Jan. 19, 1937..

Filed Sept. 16, 1935 5 Sheets-Sheet 3 3 MW Edwin FjVl'cizol Patented Jan. 19, 1937 UNlTD STATES lCE Edwin F. Nickol, Inc.,

ration of Ohio Versailles, Ohio, a corpo- Application September 16, 1935, Serial No. 40,836

4 Claims.

This invention relates to a molding apparatus.

The object of the invention is to provide, in a manner as hereinafter set forth an apparatus of the class referred to for producing a metallic reinforced concrete structure.

A further object of the invention is to provide, in a manner as hereinafter set forth an apparatus of the class referred to for producing the body and lid sections of a burial vault of metallic reinforced concrete.

A further object of the invention is to provide, in a manner as hereinafter set forth an apparatus of the class referred to for producing a metallic reinforced concrete structure with the reinforcement in the form of a reticulated basket carrying angle-shaped bars and with the points of mergence of the stretches or legs of the bars disposed at the corners of the basket.

A further object of the invention is to provide, in a manner as hereinafter set forth, an apparatus for the purpose referred to including a pair of elements for forming a pair of molding chambers, and each of said elements being provided with means to prevent the leakage of the material being molded during the molding operation.

Further objects of the invention are to provide, in a manner as hereinafter set forth, an apparatus for the purpose referred to which is strong, durable, readily assembled, thoroughly efficient in its use and having the elements thereof conveniently handled when occasion requires.

A further object of the invention is to provide, in a manner as hereinafter set forth a molding apparatus including a pair of knock down elements for forming a pair of molding chambers, a pair of cores for suspension in said chambers and each of the cores being in the form of a unitary body for bodily positioning in and removal from one of said chambers. One of said elements and one of the cores associated to produce a metallic reinforced concrete body section of a burial vault and the other element and core associated to produce a metallic reinforced concrete lid section for the body section of the vault.

With the foregoing and other objects which may hereinafter appear the invention consists of the novel construction, combination, and arrangement of parts as will be more specifically described, and are as illustrated in the accompanying drawings wherein is shown an embodiment of the invention, but it is to be understood that changes, variations and modifications may be resorted to which fall within the scope of the invention as claimed.

In the drawings:

Figure 1 is a longitudinal sectional view of that structure of the apparatus for molding the body section of the burial vault,

Figure 2 is a cross sectional view of the struc- 5 ture shown in Figure 1,

Figure 3 is a longitudinal sectional view of that structure of the apparatus for molding the lid section for the body section of the burial vault,

Figure 4 is a cross sectional view of the structure shown in Figure 3,

Figure 5 is a perspective view of the form of reinforcement employed for eaclr of the outer wall members of the structure shown in Figure 1,

Figure 6 is a top plan View of the metallic reinforcing unit for the body and lid sections of the burial vault,

Figure 7 is a perspective view, Figure 8 is a longitudinal sectional View and Figure. 9 is a 20 cross sectional view of the burial vault produced by the apparatus.

The apparatus includes a pair of molding structures it, it for producing a burial vault [2 (Figures 7, 8 and 9) formed of an open top peripherally ribbed body section i3 and an open top flanged closure or lid section it for the section l2. Each of the said sections consists of a molded metallic reinforced concrete body.

The structure it includes a molding chamberforming element l5 and a core to associated with the'latter. The structure It includes a molding chamber-forming element H and a core l8 associated with the latter. When structure I0 is employed; for molding vault section i3 there is associated therewith any suitable means, not shown, for vibrating it to provide for the settling and proper distribution of the concrete throughout the molding chamber provided by element 15. When structure it is employed for molding vault section It there is associated therewith any suitable means, not shown, for vibrating it to: provide for the. settling and proper distribution of the concrete throughout the molding chamber provided by element ll. 45

With reference to structure E0, the element l5 thereof includes a pair of oppositely disposed outwardly inclined side

wall forming members

19, 20 of like construction. Each of said members consists of a rectangular sheet of metallic material of the desired guage, width and length. The top of each of said members is formed with an outwardly bent downwardly flanged part 2! to provide a combined support and coupler of the same length as that of the member. The 55" bottom of each of said members is formed with an outwardly bent upwardly flanged part 22 to provide an abutment. Each of said members between its top and bottom is lengthwise outset to form a laterally disposed hollow extension 23 to provide a groove 24 forming a continuation of the molding chamber to be referred to. The groove 24 is closed at each end. The ends of the groove 24 are spaced inwardly adjacent the ends of the member in which it is formed. The extension is formed with a flat top part 25, a vertical outer side part 25 and a bottom part 21 which depends at an inward inclination from the bottom of part 26.

The element l includes a pair of oppositely disposed outwardly inclined end

wall forming members

28, 28 of like construction. Each of the end members consists of a rectangular sheet of metallic material of the desired guage, width and height. The top of each of the end members is formed with an outwardly bent downwardly flanged part 38 to provide a combined support and coupler corresponding in length to the width of that of the member. The bottom of each of the end members is formed with an outwardly bent upwardly flanged part 3| to provide an abutment. Each end member between its top and bottom is outset transversely to form a laterally disposed hollow extension 32 to provide a groove 33 forming a continuation of the molding chamber to be referred to. The extensions 32 are of the same contour as that of the extensions 23. Each extension 32 terminates at the side edge of the end member of j which it forms a part. The groove 33 is open at each end. The position of the extensions on the end members corresponds to the position of the extensions on the side members.

The element l5 includes a rectangular bottom member 34 having a metallic liner 35 throughout its upper face and flush with the edges thereof. The member 34 has its edges outwardly inclined throughout from its lower face. The side wall forming members have their lower portions abut the side edges of the bottom member 34. The side wall forming members are of greater length than that of and extend laterally from the ends of the side edges of member 34. The end wall forming members correspond in width to the length of the end edges of member 34 and have their-lower portions abut the said end edges and are flush with the side edges of member 34. The side edges of the end wall forming members abut the inner faces of the side wall forming members when the said several wall forming members are coupled together to provide a molding chamber 36. The lined member 34 provides the bottom of chamber 35. When the said several wall forming members are coupled together the grooves 33 open into the grooves 24 and the ends of the extensions 32 abut the ends of the extensions 23 whereby the

grooves

24, 33 form an endless continuation of the chamber 35.

The element l5 includes

channel irons

31, 38 mounted in the parts 22, 3| respectively, and extending through said parts and irons are holdfast means 39 for detachably securing the side and end wall forming members to a support 48 upon which is mounted the bottom forming member 35. The holdfast means 39 also maintains the several wall forming members in abutting relation with respect to the edges of member 35. The parts 22, 3| seat on the support 40.

The side wall forming members inwardly adjacent their ends are provided with superposed openings 4| for the passage of tie-elements 42 for detachably coupling said members together and for maintaining the side members in abutting relation with respect to the side edges of the end members.

To prevent leakage of the molding material at the joints between the side and end Wall forming members during the molding operations, the inner faces of the members H3, 28 have anchored thereto angle irons 43 which overlap the outer faces of the

members

28, 29 at the sides of the latter.

To prevent the bulging of the side

wall forming members

19, 20 below the extensions 23 during the molding operation, there is secured lengthwise of the outer face of each of said members a reinforcing element 44 (best shown in Figure 3) consisting of an inwardly opening channel iron 45 provided with side flanges 46 and apertured end closures 41. The ends of the body of iron 45 are cutout as at 43. Integral with the outer side of iron 45 centrally thereof is a laterally disposed lug 49. Extending through the cutouts 48 and closures 4'! and mounted against lug 49 is a truss brace 58 in the form of a rod having threaded terminal portions with which engage securing nuts 5| adapted to abut the outer faces of the closure 41. The flanges 46 are anchored to the outer face of a side wall forming member.

The metallic reinforcing unit for and which is to be embedded in the concrete providing the body section I3 of the vault l2 consists of a rectangular metallic basket 52 formed of reticulated material and superposed angle-shaped bars 53 arranged in spaced relation and connected to the outer face of the basket. The points of jointure between the legs or stretches of a bar oppose a corner of the basket. The manner in which the bars are disposed relative to the basket is shown in Figure 6. The structure l8 includes removable means for suspending the concrete reinforcing element within the molding chamber 36 adjacent the bottom and side and end walls of the latter. The said means consists of spaced removable hooks 54 mounted on the parts 2| of the members i9, 28 and on the parts 38 of the

members

28, 38. Each hook has depending curved end portions 55, 56 formed to detachably overlap respectively the flange of a part 2| or 38 and a bar 53. The hooks 54 are of a length to extend inwardly beyond the side and end walls of chamber 36 when suspending the basket 52.

The core |6 of structure If! is hollow and includes a rectangular open top body part 51 formed at its top with an inwardly extending fiat rectangular endless flange 58. The body part 5'! includes a pair of oppositely outwardly inclined sides 59, a pair of oppositely outwardly inclined ends 60 and a flat rectangular bottom 6|. Secured to said body part 51 throughout the outer faces of its sides 59 and ends 68, the upper face and inner edge of the flange 58 and the lower face of bottom BI is a metallic facing 62. Within the body part 51 and arranged at its sides and ends are brace bars 63. Mounted upon the bottom 6| are three spaced parallel upstanding supports 64. Arranged on the upper end of the supports 64 is a longitudinally extending coupler bar 65 disposed on the lengthwise median of body part 5?. Positioned on the ends of the bar 65 are upstanding supports 66 and on the center of bar 65 an upstanding in parallel spaced relation and abut the lower faces of the flange 58. Arranged on the

supports

68, 61 between the inner edge of flange 58 are three filler strips 88 which align with the upper face of that portion of the facing 82 mounted on flange 58. The core It includes a pair of spaced parallel suspension bars 89 therefor which are disposed transversely of and are of greater length than the width of body part 51. The bars 69 are formed with outer vertical openings 18 in close proximity to the ends thereof and inner vertical openings 1I between the openings 18 and the vertical medians of the bars. The bottom 8|, outer supports 84, bar 85, supports 68, outer strips 68 and suspension bars 69 are clamped together by spaced parallel tie means 12 extending through the openings "II, openings 14 in the outer filler strips, openings 15 in the supports 68, openings 18 in the outer supports 64, openings 11 in the bottom GI and countersunk in openings 18 in the facing 62. The central support 84 is suitably anchored to body part 51. The core It includes a lifting element 19 therefor which includes an upstanding inverted yoke 88 having its sides extending through openings M in the central filler strip, openings 82 in the support 81 and are arranged at the sides of and depend below the bar 65. Positioned against the bottom of bar 65 is a plate 83 formed with openings for the passage of the sides of the yoke. Carried on the lower ends of the sides of the yoke are securing nuts 84. When the core I8 is suspended within the element I5 it is detachably anchored thereto and in this connection it will be stated that the bars 89 are supported at their ends upon apertured spaced spacing blocks 85 mounted on the parts 2I of the members I9, 28 adjacent the hooks 54. The means for detachably anchoring the core to the element I5 consists of spaced holdfast devices 88 extending through the openings 18 in bars 68, through the apertured blocks 85, through the parts 21 of the members I9, 20 and through inverted channel irons 86 arranged below and confined in the said parts 2! inwardly adjacent the depending outer ends 55 of the hooks 54.

.The element I1 of structure U includes a pair of oppositely disposed side

wall forming members

81, 88 and a pair of oppositely disposed end

wall forming members

89, 88. Each of said side wall forming members is constructed from a rectangular sheet of metallic material of the desired guage, width and length. Each of said end wall forming members is constructed from a sheet of metallic material of the desired guage, width and height. The side members are of like construction and each consists of a vertical top portion 9|, an inwardly inclined intermediate portion 92 depending from the portion 9| and a vertically disposed lower portion 93 of materially less height than the portion 9|. The upper end of the latter is formed with an outwardly bent downwardly flanged part 94 forming a combined coupler and support. The lower end of portion 93 is provided with an outwardly bent upwardly flanged part 95 providing a combined retainer and abutment. The end members are of like construction and each consists of a vertical top portion 98, an inwardly inclined intermediate portion 81 depending from the portion 98 and a vertically disposed lower portion 98 of materially less height than the portion 96. The upper end of the latter is formed with an outwardly bent downwardly flanged part 99 providing a combined coupler and support. The lower end of the portion 88 is provided with an outwardly bent upwardly flanged part I80 forming a combined retainer and abutment. The parts 95, I88 are mounted upon a rectangular frame IIlI which is seated upon a support I82 for structure II. The frame I81 has its upper face provided throughout with a metallic facing I83. Mounted on the facing I88 as well as being suitably secured therewith is an inverted hollow frusto tapered rectangular upstanding member I84 having its inner side and upper face formed throughout with a metallic facing Iil i The latter and frame I83 in connection with a portion of the facing I88 and a portion of the frame I8I provide the bottom of the molding chamber I85. The side and end walls of the latter are formed respectively by the said side and end members. The end members 89, are arranged between, abut the inner faces of and are positioned inwardly adjacent the ends of the

side members

81, 88. The portions BI, 82 and 93 of the

members

81, 88 abut the end edges respectively of the

portions

88, 91 and 98 of the members 89, 98. To prevent leakage of the molding material at the joints between the

members

81, 88, 89 and 88 the inner faces of the

members

81, 88 have secured thereto angle irons 106 which overlap the outer faces of the members 81, 98 bordering the side edges of the latter. The

members

81, 88, 89 and 98 are detachably held in abutting engagement by a pair of upper tie devices I81 and a pair of lower tie devices I08. The upper tie devices are arranged at and extend through the portions 8! of

members

81, 88 outwardly adjacent the portions 98 of the members 88, 98. Positioned against the outer faces of the portions 92 of the

members

81, 88 are spaced triangular-shaped apertured blocks I89. The lower tie devices I88 extend through the blocks I89 and the portions 92 of the

members

81, 88 outwardly adjacent the portions 91 of the

members

89, 90.

The metallic reinforcing means for the concrete forming the lid section M of the burial vault I3 consists of a rectangular metallic frame III! of reticulated material formed with a flared lower portion III. Arranged at the point of mergence of the upper end of the lower portion III with the bottom of the remaining portion of the frame H8 is a partition H2 formed of a reticulated metallic material. The frame I I8 is encompassed by metallic reinforcing bars II3 of angle-shape arranged in the same manner relative to the frame I I8 as the reinforcing bars are arranged with respect to the basket heretofore referred to, that is the manner in which the bars and basket are arranged relatively to each other as shown in Figure 6. The bars II 3 are connectedto the frame I18. Positioned against the lower face of and connected to partition H2 are spaced metallic reinforcing bars H4. The frame II 8 is suspended in the chamber I05 in spaced relation with respect to the

members

81, 88, 89 and 98 by means corresponding in arrangement and structure as the suspension for the basket shown in Figures 1 and 2. The suspension means shown in Figures 3 and 4 are indicated at H5. The parts and 88 are anchored to the frame I81 by the holdfast devices II6 extending through the said parts, through the facing in frame I81 and engaging in the latter.

The core I8 of the structure II comprises a hollow open top rectangular body part II1 formed at its top with an inwardly extending fiat endless rectangular flange H8. part I I1 includes a bottom II9, a pair of outwardly oppositely inclined sides I20 and a pair of outwardly oppositely inclined ends I2I. The body part I I1 is reinforced at sides and ends by upstanding braces I22 which extend from bottom H9 to flange II8. Extending throughout the outer faces of the sides and ends, the upper face and inner edge and lower faces of the bottom of body portionII1 is a metallic facing H9. Disposed transversely of and within body part H1 is a pair of spaced parallel upstanding supports I23 which are disposed between opposite sides of the transverse median of and the ends of body part II1. Positioned at its ends upon the supports I23 is a coupler bar I24 extending lengthwise of body part II1. Disposed transversely of, above and of greater length than the width of body part II1 is a pair of spaced parallel suspension bars I25 having a pair of outer vertical openings I26 adjacent their ends and a pair of inner vertical openings I21 spaced inwardly from the openings I28. The bars I25 are seated on spaced apertured supports I28 mounted on the parts 94 of the

members

81, 88 adjacent the means II5 on such parts 94. Extending through the openings I21 in bars I25, openings I29 in bar I24, openings I3I in bot-. tom H9 and countersunk in the facing II9 are spaced tie devices I32 for clamping together body part II1, supports I23, bar I24 and bars I25 together to form bodily movable unit.

The core I8 includes a shifting element I33 for positioning it within and removing it from the element I1. The element I33 includes an inverted yoke I34 having its sides arranged at the sides and depending below the bottom of bar I24. Mounted on the lower ends of the sides of yoke I34 is an apertured coupling plate I35 secured on yoke I34 by the holding nuts I35.

When the bars I25 are mounted on the blocks I28, the core I8 is suspended in the element I1 in spaced relation to the sides, ends and bottom of the chamber I05, and it is also spaced from the frame H0 and partition H2. The core I8, when suspended in element I1 is detachably anchored to the latter and to the support IOI For the purpose four tie devices I31 are employed. A pair is associated with each bar I25. Each device I3II consists of a pair of rods I38, I39. The rod I38 has a loop I40 at its lower end. The rod I39 has a loop I4I at its upper end. The loops I40, I4I are interengaged for loosely connecting the rods I38, I39 together. The upper end of rod I38 is threaded. The lower end of rod I39 is threaded. The rods I38 extend through the openings I28 in bars I25, through the apertured blocks I28, the parts 94 of

members

81, 88, and channel irons I42 arranged below and within the parts 94. The rods I39 extend through the support IOI. The upper ends of rods I38 carry securing nuts I43. The lower ends of bars l39 carry securing nuts I44 which coact with the nuts I43 for maintaining the tie devices I31 in position to detachably anchor element I1 and core l3 together and to detachably anchor structure II to support I02.

The element I1 includes four spaced short rods I45, only two shown, which extend from the side

wall forming members

81, 88 to the facing I84= of the member I04. These rods I45 are suitably secured in position and have their inner ends positioned substantially in relation to the corners The body of member I04. The rods I45 incline downwardly'from their outer to their inner ends.

The lid section I4 of the vault I2 is to have anchored therein couplers for detachably connecting to said section a lowering means, not shown and for such purpose a pair of spaced parallel coupling elements I 46, only one shown, is arranged in each side of the chamber I05. Each element I46 includes a body part I41 formed with a pair of outwardly extending spaced parallel stems I48, only one shown which have threaded outer portions for receiving nuts I49 for detachably connecting with the lowering device. The body part is positioned against the inner face of frame I I0 above the tapered lower portion of the latter. The stems I48 extend through the frame IIO across chamber I and through

members

81, 88.

The body section I3 of the vault I2 has its sides and ends formed with laterally extended ribs I 50 between the upper and lower ends thereof. The sides of the section I3 are oppositely outwardly inclined. The ends of the section I3 are oppositely outwardly inclined. The metallic reinforcing means for the section I3 of the vault is designated at I5I and is embedded in the sides, ends and bottom of said section. The ribs I50 on the section I3 are formed by the

grooves

24, 33 in the side and end wall forming members of chamber 30.

The lid section I4 of the vault is formed in its top with an enlarged rectangular cavity I52 provided by the member I04. The lid section I4 is formed with a depending rectangular flange I53 which is to oppose section I3, in a manner as shown in Figures 8 and 9 to form a tapered recess or space I54. The flange I53 does not extend to the ribs I50. The flange I53 is formed by the portions 9| of the

side members

81, 88 and the portions 96 of the

side members

89, 90. The lid section includes drainage openings I55 for cavity I52 which are provided by the bars I45 of element I1. The means for detachably connecting a lower device to lid section are arranged in and project from the sides of the flange I53 and are indicated at I56 Figure '7. The metallic reinforcing means for lid section I4 and designated at I51 is disposed throughout the flange I53 and arranged around the side and ends of and below the bottom of cavity I 52.

What I claim is:

1. In a molding apparatus, a pair of end walls, a pair of side walls abutting and extended outwardly from the side edges of the end walls, a bottom coacting with said walls providing a molding chamber, each of said walls at its top being formed with an outwardly directed angleshaped part having a horizontal leg and a vertical leg depending from said other leg and constituting a combined support and coupler, spaced elements seated on, disposed transversely of, extending inwardly from and inter-engaging with the vertical legs of said parts constituting means for suspending a metallic reinforcing unit within said chamber in spaced relation to the inner faces of said walls and bottom, outwardly directed flanges at the lower ends of said walls, means coacting with said flanges for detachably maintaining said walls upstanding, tie devices extending through and coacting with the extended portions of the side walls for detachably maintaining the inner faces of the side walls against the side edges of the end walls, spaced upstanding supports mounted on the said parts of said side walls, a core for suspension in said chamber in spaced relation to said unit and provided with suspension bars seated on said spaced supports, and means for detachably clamping said bars, spaced supports and said parts of said side walls together.

2. In a molding apparatus, a pair of end walls, a pair of side walls abutting and extended outwardly from the side edges of the end walls, a bottom coacting with said walls providing a molding chamber, each of said walls at its top being formed with an outwardly directed angleshaped part having a horizontal leg and a vertical leg depending from said other leg and constituting a combined support and coupler,

each of said walls between its top and bottom being formed with an outwardly directed, hollow extension forming a groove providing an outward continuation of said chamber at the sides and ends of said chamber, the grooves in the end walls opening into the grooves of the side walls, spaced elements seated on, disposed transversely of, extending inwardly from and interengaging with the vertical legs of said parts constituting means for suspending a metallic reinforcing unit within said chamber in spaced relation to the inner faces of said walls and bottom, outwardly directed flanges at the lower ends of said walls, means coacting with said flanges for detachably maintaining said walls upstanding, tie devices extending through and coacting with the extended portions of the side walls for detachably maintaining the inner faces of the side walls against the side edges of the end walls, spaced upstanding supports mounted on the said parts of said side walls, a core for suspension in said chamber in spaced relation to said unit and provided with suspension bars seated on said spaced supports, and means for detachably clamping said bars, spaced supports and said parts of said side walls together.

3. In a molding apparatus, a pair of end walls, a pair of side walls abutting and extended outwardly from the side edges of the end walls, a bottom coacting with said walls providing a molding chamber, each of said walls at its top being formed with an outwardly directed angleshaped part having a horizontal leg and a vertical leg depending from said other leg and constituting a combined support and coupler, spaced elements seated on, disposed transversely of, extending inwardly from and inter-engaging with the vertical legs of said parts constituting means for suspending a metallic reinforcing unit within said chamber in spaced relation to the inner faces of said walls and bottom, outwardly directed flanges at the lower ends of said walls, means coacting with said flanges for detachably maintaining said walls upstanding, tie devices extending through and coacting with the extended portions of the side walls for detachably maintaining the inner faces of the side walls against the sideedges of the end walls, spaced upstanding supports mounted on the said parts of said side walls, a core for suspension in said chamber in spaced relation to said unit and provided with suspension bars seated on said spaced supports, means for detachably clamping said bars, spaced supports and said parts of said side walls together, and a reinforcing structure for each side wall to prevent the bulging thereof, said structure being secured to the outer faces of said side walls below the longitudinal medians thereof, disposed lengthwise of such walls and including truss braces.

4. In a molding apparatus, a pair of end walls, a pair of side walls abutting and extended outwardly from the side edges of the end walls, a bottom coacting with said walls providing a molding chamber, each of said walls at its top being formed with an outwardly directed angleshaped part having a horizontal leg and a vertical leg depending from said other leg and constituting a combined support and coupler, each of said walls between its top and bottom being formed with an outwardly directed, hollow extension forming a groove providing an outward continuation of said chamber at the sides and ends of said chamber, the grooves in the end walls opening into the grooves of the side walls, spaced elements seated on, disposed transversely of, extending inwardly from and inter-engaging with the vertical legs of said parts constituting means for suspending a metallic reinforcing unit within said chamber in spaced relation to the inner faces of said walls and bottom, outwardly directed flanges at the lower ends of said walls, means coacting with said flanges for detachably maintaining said walls upstanding, tie devices extending through and coacting with the extended portions of the side walls for detachably maintaining the inner faces of the side walls against the side edges of the end walls, spaced upstanding supports mounted on the said parts of said side walls, a core'for suspension in said chamber in spaced relation to said unit and provided with suspension bars seated on said spaced supports, means for detachably clamping said bars, spaced supports and said parts of said side walls together, and a reinforcing structure for each of said side walls to prevent the bulging of the latter, said structures being arranged below the groove-forming extensions of said side walls, anchored to and disposed lengthwise of the side walls and including truss braces.

EDWIN F. NICKOL.