US1557697A - Boom - Google Patents

Description

6. HOLMES BOOM ' Filed pril as. 1924 s sheets-Shea 1 Hum 11 I: l

//V VENTOR GRA N H01. MfS,

ATTOfP/VL'K G. HOLMES BOOM Oct. 20,19 5. 1.557.697

Filed April 28. 1924 S Sheets-Sbeet 2 //V l/E N TOR. GRAN T HOLMES.

G. HOL MES BOOM Filed AP711 28. 1924 3 Sheets-Sheet 5 l I I I I I I I I I I I I I I I I I I I I I /N VE N TOR. GRANT HOLMES.

arrow/EX Patented Oct. 20, 1925.

I UNITED STATES'IPATE'NT oFF1 9 GRANT HOLMES, or DANVILLE,ILLINoIsns-smrioa To THE MAaioN STEAM- srrovEL COMPANY, or MARION, onto. it CORPORATION or 01110.

BOOM.

Application filed April 28, 1924. Serial No. 703,428.

1 '0 all whom it may concern:

Be it known that I, 'GRANT HOLMES, a citizen of the United States, residing at Danville, in the county of Vermilion and State of Illinois, have invented certain new and useful Improvements in Booms of which the following is a specification, reference being had therein to the accompanying drawing.

, compression.

This invention relates to booms and is in the nature of an improvement on the boom structure shown and described in application for patent filed by me July 30, 1923, Serial No. 654,568. Rotary power shovels as constructed in the past have for the most part comprised a rotary frame on which the boom was mounted,the foot of the boom usually resting in a socket or between ears at the front end of the frame and extending upward and forward at an angle of about forty-five degrees. The boom is held in this position by suspension from the point thereof by means of cables or hog 'rods extending from the boom to a gantry or A-frame, mounted on the revolving frame and braced or stiffened by meansof a bridge,-

which bridge also provides a high point for connectmg the cables or hog rods. The boom itself is usually heavier, or of greater size. near the center thereof and the upper and lower sides or edges thereof converge forwardly and rearwardly. The shipper shaft and crowding engine are mounted on this heavier portion of the boom and the dipper handle extends through the boom adjacent to the shipper shaft. When a machine of this character is not working and the dipper is resting on the ground the boom is subject to certain strains, the under side of the boom being under tension and the upper side of the boom being in When the dipper is raised off the ground these strains are proportionately increased, it being understood that in the larger types of shovels these dippers are of large size and even when empty impose a heavy load on the boom. When the.

shipper shaft and this thrust serves to reverse the strains imposed upon the boom, the lower side of the boom being placed under compression and the upper side of the boom being placed under tension. After the dipper has finished its out and the weight of the loaded dipper imposed on the boom the strains are again reversed, bringtakes place at frequent intervals and is highly destructive of the boom. As has been stated most booms of this character are heavier adjacentto the shipper shaft but the portion of the boom between the shipper shaft and the point is subjected to these constantly reversing strains with the result that it is graduallyweakened to the breaking point. Further, the swinging of the loaded dipper imposes a very severe twists ing strain on the lower or foot portion of the-boom. which is smaller insertion, usually about one-third of the distance from a the foot of the boom tothe shipper shaft and thisstrain gradually weakens this por-' tion of the'boom to the breaking point.

These strains are present in all booms of this character but they become more pronounced 1n the larger size machines and it has been found impractical to increase the size and strength of a boom of this kind sufficiently to overcome the destructlvefaction of the strains upon the boom.

One object of the present invention isto provide'a boom of great strength which will be compact in its arrangement and of a relatively light weight, as compared with its strength.

A further object of the invention is'to' provide a boom of this characterthe upper lateral edges of which will each constitute a straight line from the point of the boom to the rear end of-the supporting structure or platform.

A further object ofthe invention is to provide such a'boom structure in which the boom and the frame members will be rigidly braced and reinforced against the strains to'which the structure is subjected in operation. I

Other objects of the invention will appear as the device is described in detail.

In the accompanying drawings Fig. 1 is: a side elevation of a boom structure embodying my'invention, showing the same as ap plied to a power shovel of the rotary type;-

Fig. 2 is' a longitudinal section through the frame and a portion of the boom proper, on the line 22 of Fig. 5; Fig. 3 is a longitudinal section through one of the side members of the frame and a portion of the, boom, on the line 3-3 of Fig. 5; Fig. 42 1s a transverse section taken on the line 4.4 of Fig. 1 Fig. 5 is a top plan view of the boom structure; Fig. 6 is a bottom plan View of the same; Fig. 7 is a section taken on the line 7-7 of Fig. 1; Fig. 8 is a rear elevation of the boom structure; Fig. 9 is a section taken on the line 99 of Fig. 1; Fig. 10 is a section taken on the line 1O 10 of Fig. 1; Fig. 11 is a detail View of the horizontal reinforcing plates; Fig. 12 is a detail view of one of the side'm'embers of the frame portion of the structure; Fig. 13 is a side elevation of a portion of one of the plates of the boom portion ofthe structure; and Fig. 14 is a detail, elevation of the vertical reinforcing plates.

In these drawingsl have illustrated one embodiment of my invention and have shown the same as applied to a rotary power shovel but it will be understood that the invention may take various forms and that the boom may be used in connection with mechanisms of various kinds without departing from the spirit of the invention.

In the particular embodiment here shown the excavating machine or power shovel comprises a base or truck frame 1 on which a platform or supporting frame '2 is mounted for rotation about a vertical axis. This revolving platform carries the boom structure, the power plant and the operating and controlling mechanism. The boom structure as a whole comprises two parts; a frame portion, consisting of side members mounted along the lateral edges of the revolving platform 2, and a boom portion supporter at the forward end of the platform, extending upwardly and forwardly therefrom and rigidly secured to the frame portion so that the two parts constitute a singlestructure.

.The side members of the frame portion of theboom structure may be constructed in various ways but I prefer that the cons-truction should be of plates as described in the above mentioned application. I have therefore shown each side member of the frame 7 portion of the boom structure as comprising {a plate 3 which is substantially triangular in form and is mounted at its lower edge along'or adjacent to the lateral edge the platform, the lower edge of the plate being preferably parallel with the adjacent edge of the platform. The plate may consist of a single sheet o-f-metal but because of its size it will ordinarily be made upof a number of sheets riveted one to the other to form a single plate or structure. The inclined edge of the triangular plate extends upwardly fromthe rear end of the platform to a point above the forward end of the platform and the plate is tilted inwardly so that this upper inclined edge will overhang the platform. The upper edge of the plate being inclined and the plate as a whole being tilted it will be apparent that the upper inclined edge of the plate will extend obliquely to the edge of the platform. This plate is suitably reinforced or braced and, as here shown, a series of bunkers or brace plates i extend transversely to the side plate 3 and are rigidly secured thereto at their outer edges, as by means of angle irons. The inner edges of the base plates are reinforced by angle irons 5 rigidly secured thereto. The lower ends of the plate 4: and angle irons 5 are secured to the platform '2. supported on the upper edge of the side plate 3 and extends across the brace plates or;

bunkers 4, this top plate being secured to the upper edge of the side plate and to the upper inner corners of the brace plates by means of angle irons 7. Extending transversely between the two side members of the frame portion of the structure and preferably arranged at approximately the level of the roof of the cab is a horizontal member "here shown as a plate 8 rigidly secured at its edges to the frame members and serving to tie these members together and brace them one against the other. Arranged at the for-.-.

ward ends of each of the side members and rigidly secured to the forward edges of the tion of a reinforcing and bracing member the plate 8 may also serve as the roof for the forward portion of the cab, the side n'iembers 3 forming in part the side walls of the cab, the rear portion of which may be built onto the rear inclined portion of these side members. as shown in dotted lines at'lO on l. Further'this plate 8 provides a work platform above the operating mechanism.

The boom portion of the structure may be supported at its lower rear end upon the platform 2 and extends upwardly and forwardly therefrom. the upper and lower edges converging toward the point of the boom and the lateral edges of the boom also converging toward the point of the boom, so as to provide a tapered boom structure the lines'of which will be straight. This boom structure may take various forms of construction but following out the plate construction of the frame portion of the structure I have formed the boom of two upright plates 11 arranged parallel one with A top plate 6 is The the other and having their upper and lower edges tapered toward the point of the boom and spaced a relatively short distance one from the other, thus providing a space through which the dipper handle 12 may extend. These upright plates are connected one to the other by inclined plates 13, 14 and 15, to brace them one against the other and the plates l i and 15 are so arranged as to provide a suitable space for the operation of the dipper handle.

the two upright plates 9 and are rigidly secured thereto, the lower edges of the plates 11, as shown at 16, may, if desired, rest upon the forward portion of the platform 2. Rigidly'secured to the rear edges of the plates 11, above the plates 9, is a transverse upright plate 17 which extends between and is rigidly secured to the side membersand to the horizontal plate 8. The upright plate 17 is arranged in line with the plates 9 and the three plates form in effect a single upright member which is secured at its lateral edges to-the side members 3 and to which the rear ends of the parallel boom members, 11' are secured. To the outer sides of each of the.

boom plates 11 is secured a hdrizontal plate 18, which plates are arranged substantially;

in line with the horizontal plate 8 and are rigidly secured at their rear edges to the upright plates 9 and 17. These horizontal plates 18 are substantially rectangular in shape and terminate at the lower edge of the boom plates some distance in front of the side frame members3. Arranged between the boom plates 11 and in line with the plates 18 is a plate 29 which is rigidly secured at its lateral edges to the respective boom plates. braced by a series of outwardly extending transverse bunkers or brace plates 19 rigidly secured at their inner edges to the respective boom plates, as by means of angle irons20, and reinforced at their outer edges by angle irons 21. Extending across the upper edges of the boom plates is a top plate 22 which is rigidly secured to the upper edges of both boom plates and extends laterally beyond the same to the. edges of the brace plates 19 to which it is securedjby means of angle irons, or in any other suit-- able manner. This top plateis arranged in the same plane withand forms a'continuation of the top plate 6 of the side members,

so that these top plates constitute in effect a 2 single top plate extending from the point of the boom to the rear end of the platform and bifurcated at its rear end to conform to the arrangement of the side members It is also provided with openings 23 and 24 to permit the passage of the dipper handle and to receive the sheaves at the point of the boom. p, Rigidly secured to the lower edges of the boom plates and extending outwardly The lower portions of the rear ends of the plates 11 extend between The boom plates are reinforced or their rear edges to the uprightplates' The lower edges of these triangular plates but spaced some distance from the outer edges of the bottom plates 25. Consequently the rear edges of the plates 26 extend diagonally to the plates 9. It will be noted that the reinforcing plates or bunkers 19 at the rear end of the boom are secured at their inner edges of the triangular plates 26' and are spaced some distance from the boom members 11. Further, I have here shown the bottom plates 25 under this portion .of

26 are arranged substantiallyparallel with the boom as of a width'correspondin'g to the I -width of 'tl e bunkerplates 19, thus leaving a space'between' the bottom plates 25 and the vboom plates. It will! be noted that the up per edges of the side members 3 are in line with the outer upper edges of the boom so that the lateral edges of the top plates 6 and 22, which follow the edges of the frame plates and the boom, constitute straight lines extending. from the point of theboom members and boom members are rigidly connected one to the other so as to form a unl- 1 tary structure which is rigidlybraced, by

structure vin the field. It. is thus possibleto assemble the boom portion of the structure in ahorizontal position, upon suitable sup porting structures, pivotally I connect the to the rear end of the platform 2. The

lower lateral edges of the boom form straight linesfrom the point of the boom to the forward end of the platform. The frame" The lower; edgeof the .otal connection is primarily for the purpose 2 'of facilitating the assembly of the boom same to the frame portion-of the structure" and by then attaching to the point of the boom cables leading to the hoisting mechanism on theplatform the boom can behoist- 7 ed into its normal position and rigidly se- 1 cured in, t at position and when so arranged the weight and thrust of-the boomjwill come,

upon the platform itself and not upon the A hinges. -As here shown, I have arranged a hinge 27 between the lower edges of the boom plates 11 and the front edge of the platform 2 and have arranged other hinges 28 between the outer portions of the boom and the platform. The intermediate hinge 27 not only establishes a pivotal connection between the boom plates and the platform but when the boom structure has been assembled with the parts in their normal posi-- tions this hinge forms a firm connection be tween the lower corners of the boom plates and the platform. As here shown the hinge 27 comprises a hinge member 30 rigidly secured to the front end of the platform and a second hinge member 31 connected with the hinge member 30 by a hinge pin 32. The hinge member 31 is preferably in the form of a casting arranged to fit between the two boom plates 11 and having upright portions or flanges 33 to which the boom plates are rigidly secured. This hinge member is so shaped and arranged that when the boom is in its elevated position the hinge member will rest upon the platform 2. If desired, the member 31 may be provided on each side witha shoulder 34: on which the edges of theboom plates rest.

The arrangement of the horizontal and vertical transverse reinforcing plates is such as to impart to the structure a high degree of rigidity and to firmly brace the same against the strains to which it is subjected in the normal operation of the machine. It will be noted that the group of horizontal plates and the group of vertical plates each constitutes'in effect a single member or plate the two members being arranged in intersecting planes. The upright or vertical plates 9 and 17 constitute in effect a single plate or member rigidly secured at its lateral edges to the frame members 3 and to which the rear edges or boom members 11 are rigidly secured. The horizontal plates 18 and 29 also constitute in effect a single plate or member which is rigidly secured to the side members and to the boom members. Either the horizontal plate or the vertical plate may be divided into two parts at the line of intersection of the other plate and the several parts then rigidly secured one to the other. It is not essential that the boom members 11 should extend downwardly and rest upon the platform but, if desired, the triangulalrplates 26 may be relied upon to connect the boom with the platform itself. If the boom plates are terminated along the upper edges of the triangular plates 26 then the plates 18 and 29 may be connected directly one to the other and rigidly secured to the lower edges of the boom members. The important feature of the construction is the horizontal and vertical transverse reinforcing members arranged in intersecting planes and rigidly connected with the frame members and the boom plates or members.

The boom thus formed, while massive in construction, is of a compact arrangement, of relatively light weight as compared with its strength and of very great strength. The

parts thereof are rigidly braced and the boom portion of the structure is so shaped and so reinforced and braced as to provide great strength at the points of strain.- The straight line arrangement of the edges of the'structure not only provides strength but also tends to compactness and harmonious construction. Y'Vhile I have here shown and described the structure as formed of plates it will be obvious that this is not essential to the carrying out of the invention and that lattice construction may, if desired, be employed, without material change in the design and arrangement of the structure as a whole.

While I have shown and described one embodiment of my invention 1 wish it to be understood that I do not desire to be limited to the details thereof as various m0difications may appear to a person skilled in the art.

Having now fully described my inven tion, what I claim as new and desire to secure by Letters Patent, is:

1. In a boom structure of the character described, a frame portion comprising side members having their upper edges inclined upwardly from the rear end thereof, a boom portion rigidly secured to said frame portion and extending upwardly and forwardly therefrom and having its lateral edges converging toward the point of the boom and arranged in line with the lateral edges of said side members.

2. Ina boom structure, a frame portioncomprising side members spaced apart,

comprising upright side members having, their lower edges substantially parallel and having. their upper edges inclined upwardly from their rear ends to their front ends,

said side members being tilted one toward the other, a horizontal member arranged between and rigidly secured to said side members between the upper and lower edges thereof, and a boom portion rigidly secured to and extending upwardly and forwardly from said frame portion, the upper lateral edges of said boom portion converging toward the point of the boom and forming continuations of the upper lateral edgesof the side members of said frame portion.

4. The combination with a supporting p tf rm, of a een structu o p isi a its i frame portion consisting of side members mounted at'their lower edges on said platform and converging upwardly therefrom, the upper edges of said side membersbeing inclined upwardly from the rear ends thereof to the forward ends thereof, bracing members connected with said side members, and a boom portion comprising parallel members resting at their rear ends on said platform and extending upwardly and forwardly therefrom, said boom members being rigidly secured to said frame portion of said structure. a

5. The combination with a supporting platform, of a boom structure comprising a frame portion having side members resting upon and extending upwardly from said platform and having their upper edges inclined from the rear end of said platform to a point above the front end thereof, a boom portion comprising parallel members resting at their rear ends upon said platform and extending upwardly andforwardly therefrom, and transverse upright plates connect- Iiong said boom members with said side memers.

6. The combination with a supporting platform, of a boom structure comprising a frame portion having side members extending upwardly from said platform, the upper edges of said side members being in clined upwardly from the rear end ofsaid platform to a point above the front thereof, upright transverse members secured to the respective side members and extending inwardly therefrom, said upright members having their inner edges spaced one from v the other, a horizontal member rigidly'se cured to said upright members and to said side members, a boom portion comprising longitudinal members extending between and rigidly secured to the edges of said'upright members of said frame portion, the lower edges of said boom members resting" upon said platform, and an upright transverse member rigidly secured to the rear ends of said boom members and to said side members above the first mentioned upright transverse member.

7. The combination with a supporting platform, of a boom structure comprising a frame portion having side members extending upwardly from said platform, the upper edges of said side members being inclined upwardly from the rear end of said platform to a point above the front there-' of, upright transverse members secured to the respective side members and extending inwardly therefrom, said upright fmembers having their inner edges spaced one from the other, a horizontal member rigidly secured to saiduprightmembers and to said side members, a boom portion compris ng longitudinal members extending between and rigidly secured to the edges of said up 'righttransverse members.

right members of said frame portion, the lower edges of said boom members restlng upon'said platform, an upright transverse .member rigidly secured to the'rear edges of said boom members and to said side members above the first mentioned upright transverse members, and other horizontal members arranged substantially in line with the first mentioned horizontal member andiigidly secured at their edges to the respective boom membersand upright members,

8. The combination with a supporting 'wardly therefrom, said upright members having their inner edgesspaced one from the other, a horizontal member rigidly-secured to said upright members andto's'aid side members, a boom portion comprising longitudinal members extending between and rigidly secured to the edgesiof said upright members of said frame portion, the lower edges of said boom members resting upon said platform, anupright transverse member rigidly securedto the rear edges of said boom members and to said sidemembers above the first mentioned upright transverse members, other horizontal members arranged substantially in line with the first mentioned horizontal member and rigidly secured at their edges to the respective boom -members andupright members, and a triangular'plate arranged on each side 'of'said boom portion, rigidly secured at their upper edges to the respective boom members along the edges of the last mentioned horizontal members and extending downwardly and outwardly therefrom, and rigidly secured at their rear edges to the first mentioned up- 9. The combination with a supporting platform, of a boom structure comprising side plates extending upwardly from said platform and having'their upper edges inclined upwardly and forwardly, -bracing members rigidly secured to the inner faces of said side plates, a horizontal plate extending 1 between and rigidly secured to said side".

plates between the upper and lower edges thereof, andparallel plates resting at their rear edges on said platform and having their respective upper and lower edges convergingaway from said platform, bracing members rigidly secured to the outer edges of said parallel plates, and transverse upright plates rigidly connected with said parallel plates and with said side plates.

10. The combination with a supporting platform, of a boom structure comprising side pi'ates coavejr ing upwardly from said platform and having their upper edges inclined upwardly and forwardly, brace members seem-ed to and extending inwardly from the respective side plates, upright transverse plates rigidly secured to the forward edgesbf said side'plate'sand extending inwardly therefrom, said upright "plates hav-' ing their inner edges spaced apart, a horizontal plate rigidly secured at its respective edges to said side plates and to said upright plates,parallel plates having their rear edges extending between said upright plates,'resting upon said platform and having their respectiveupper and lower edges converging away from said upright plates, bracing members rigidly secured to the outer surfaces of the respective parallel plates and extending outwardly therefrom, a second up right plate rigidly securedto the rear ends of said parallel members above the first mentioned upright platesaud secured at its edges with said side plates, and a top plate rigidly secured to the upperedges of said side plates, fsaid parallel plates and said bracing ID9111- bers, and having each lateral edge constitut ing a straight line from one end "of said structure to the other.

11. The combination with a supporting platform, eta boom structure comprising side plates converging upwardly from said platform and having their upper edges inclined upwardly and forwardly, brace members secured to and extending inwardly from the respective side plates, upright transverse plates rigidly'secured to the forwant edges of said side plates and extending inwardly therefrom, said upright plates having their inner edges spaced apart, a horizontalplate rigidly secured at its respective edges to said side plates and to said upright plates, parallel plates having their rear edges extending between said upright 'blates, resting upon said platform and having their respective upper and lower edges converging awayifron said upright plates, brac members rigidly secured to the'out'er surfaces otthe respective parallel plates, and extending outwardly therefrom,

a second upri ht plate rigidly secured to the rear ends of said parallel members abovc the'fir'st mentioned upright plates and secured at its edges to said side plates, other horizontal plates arranged on the opposite sides ofsaid parallel plates in substantially the same plane with the first mentioned horizontalplate and rigidly secured to the respective parallel p" te s, and upright plates, and a top plate, SGCL .ed to the upper edges of said parallel plates and the bracing members therefor and having its lateral edges arranged in line with the upper edges of the respective side plates.

12.;The coino'ination with a supporting platform, of a' booin structure comprising side plates converging upwardly from said platform and having their upper edges inclined upwardly and forwardly, brace mein bers secured to and extending inwardly,

from the respective side plates, upright transverse plates rigidly securedto the forwardcedge's of said side plates and extend ing inwardly therefrom, said upright plates having their inner edgess'paced apart,,a hor-- and extending outwardly therei'rom, a sec 1' end upright plate rigidly secured to the rear ends of said parallel members above "the first mentioned upright plates and secured at its, edges to said side plates, other horizontal plates arranged on the opposite, sides ol said'parallel plates in substantially the same plane with the first mentioned-horizontal plate and, rigidly secured to the re sp'ective parallel plates and upright plates,

and triangular plates secured at their upper edges to therespective parallel plates along the inner edges of the last mentioned horizontal plates and having their rear edges secured to the first mentioned uprig platesand extending diagonally thereof, 13. The combination with a supporting platform, of aboom structure comprising side plates converging upwardly from said platform and having their upper edges vinclined upwardly I v members secured to and extending inwardly from the respective side plates, upright transverse plates rigidly secured to tlie forward edges ot said side plates and extending inwardly therefrom, said upright plates having their inner edges spaced apart, a horizontal member rigidly secured at its respective edges to said side plates and tosaid upright plates, parallel plates having their rear edges extending between said upright plates, resting upon said platform, and having their respective upper andlower edges converging away TlT IOmTSZtlCl upright plates, bracing members rigidly secured to the cute surfaces of the respective parallel a second upright platerigidly secured to and' forwardly, brace ion ill)

the rear ends of said parallel plates above,

the first mentioned upright plates and secured at its edges to said side plates,cther horizontal plates arranged on the opposite sides of said parallel plates in substantially the same plane with the first mentioned horizontal plate and rigidly secured to the respective parallel plates and upright'plates triangular plates secured at their upper edges to the respective parallel plates along the inner edges of the last mentioned horizontal plates and having their rear edges secured to the first mentioned upright plates and extending diagonally thereof, and a top plate secured to said parallel members and the brace members therefor and having its lateral edges in line with the upper edges of the respective side plates.

let. The combination with a supporting platform, of a boom structure comprising triangular side plates supported at their lower edges on said platform and converging upwardly therefrom, brace plates rigidly secured to and extending inwardly from said triangular plates, top plates secured to the upper edges of the respective side members and the adjacent brace plates, upright plates secured to the forward edges of said side plates and extending inwardly therefrom, the inner edges of said upright plates being spaced apart, a horizontal plate rigidly secured at its edges to said side plates and the upper portions of said upright plates, a pair of parallel boom plates extending between the edges of said upright plates and resting upon said platform, an upright plate rigidly secured to the ends of said boom plates above the first mentioned upright plates and rigidly secured at its edges to said side plates, transverse bracing plates rigidly secured to said respective boom plates and extending outwardly therefrom, horizontal plates rigidly secured to the respective boom plates in substantially the same plane as the first mentioned horizontal plate and secured at their rearedges to the respective first mentioned upright plates, triangular plates secured along their upper edges to the respective boom plates along the inner edges of the last mentioned 1 horizontal plates and secured at their rear edges to the first mentioned upright plates along diagonal lines, and a top plate extending for the full length of said boom structure and secured to the upper edges of said boom plates and the several bracing plates therefor, and forming a continuation of the first mentioned top plates, the

lateral edges of said top plate each -con stituting a straight line for the full length of said boom structure.

15. In a structure of the character described, a platform, side members extending upwardly'from said platform near the respective lateral edges thereof, a transverse upright member secured at its edges to said vside members near the forward edges of the latter, substantially parallel uprightmembers secured at their rear edges to said trans-' verse member and extending upwardly and forwardly therefrom,and a transverse horizontal member rigidly secured to said side members and to said transverse member.

16. In a structure of the character described, a platform, side memhersextending upwardly from said platform near the ,re-

spective lateral edges thereof, a transverse bers secured at their rear edges to said transverse member and extending upwardly and forwardly therefrom, a transverse horizontal member secured at its lateral edges to said side members and at its forward edge to said transverse member, and a transverse horizontal member arranged substantially in line with the first mentioned horizontal member and secured at its rear edge to said upright transverse member and extending lengthwise of and secured to one of said parallel upright members. s

17. In a structure of the character described, a platform, side members extending upwardly from said platform near the respective lateral edges thereof, a transverse upright member secured at its edges to said side members near the forward edges of the latter, substantially parallel upright members secured at their rear edges to said transverse member and extending upwardly and forwardly therefrom, a transverse horizontal memberrigidly secured at its lateral edges to said side members and at its for-- ward edge to'said transverse member, and transverse horizontal members arranged substantially in line with the first mentloned horizontal member and secured at their rear ends to said transverse upright member and secured at their lateral edges to the respective parallel upright members.

18. In a structure of the character described, a platform, side members extending upwardly from said platform near the respective lateral edges thereof, a transverse upright member-secured at its edges to said side members near the forward edgesof the latter, substantially parallel upright members secured at their rear edges to said transverse member and extending upwardly and forwardly therefrom, a transverse horizon-v tal member rigidly secured at its lateral U edges to said side members and at its forward edge to said transverse member, trans-.

verse horizontal members arranged substancent to the last mentioned horizontal members, extending downwardly and laterally therefrom, and connected at their rear. edges with said transverse upright member.

19. In a structure of the character described, a platform, side members extending 1 upwardly from said'platform near the re- 'spective edges thereof, transversely extending horizontal and vertical nieinbers arranged 1n intersecting planes and rigidly connected With said side members, and parallel upright members rigidly secured to saic horizontal and said vertical members and extending upwardly and forwardly therefrom.

20. In a structure ot the character described, a platform, side members extending upwardly from said platform near the respective edges thereof, transversely extending horizontal and vertical members arranged in intersecting planes and rigidly connected with said side members, parallel "upright members rigidly secured to said horizontal and said vertical members and extending upwardly and forwardly there from, said upright parallel members being spaced apart adistance less than the distance between said side members, and members' rigidly secured to the respective up-- right parallel inenibers extending downwardly and outwardly therefrom a'ndrigid- 1y connected at their rear edges'witb said vertieal transverse nieinber.

In testimony whereof, Iaffix my signature hereto. r

GRAN-T HOLMES.

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