US2371071A - Tread block core for endless tracks and the like - Google Patents

Description

March 6, 1945- R. l. SCHONITZER TREAD BLOCK CORES FOR ENDLESS TRACKS AND THE LIKE Filed Jan. 14, 1942 10 Sheets-Sheet 1 /NVEN7OR RUDOLPH I. SCHONITZER 7 I aw! fizzy A'r'ronw'svs.

March 6, 1945. R SCHQNITZER 2,371,071

TREAD BLOCK CORE-3S FOR ENDLESS TRACKS AND THE LIKE Filed Jan. 14, 1942 10 Sheets-Sheet 2 //v VEN TOR RUDOLPH I. SCHONITZER m fi A T1- @g 9; 9 k 2 a 0 T Q Mm i. 3x 11 m MW TOHNEYS.

March 6, 1945. R.l. SCHONITZER 2,371,071

TREAD BLOCK CORES FOR ENDLESS TRACKS AND THE LIKE Filed Jan. 14, 1942 10 Sheets-Sheet s 101 (34101 /NVENTOR FIG 3 I RUDOLPH I. Scum/T253 BY %AM ATTORNEYS.

March 6, 1945.

R. l. SCHONITZER TREAD BLOCK CORES FOR ENDLESS TRACKS AND THE LIKE Filed Jan. 14, 1942 10 Sheets-Sheet 4 l a]? i l ,1! l 41 I iii a :2: 5 i=2 41 V W 5 5H I l jg L as E i-i: l 4 k .14. iii: i III/I/II/ [III/Ill] '2 38 I 2// /3 RUDOLPH I. Scuomvzm. /l'III/I/I/i Fez/2 M I Arron/v Ys.

March 6, 1945. R. SCHONITZER 2,371,071

TREAD BLOCK CURES FOR ENDLESS TRACKS AND THE LIKE Filed Jan. 14, 1942 10 Sheets-Sheet 5 IIIIIIIIIIIIII IIIIII/IIIIIII/II/[I/I/ /N VENTOf? R0001. PH 1'. SCHON/TZER TTORNEYS.

March 6, 1945- R. l. SCHONITZER TREAD BLOCK CORES FOR ENDLESS TRACKS AND THE LIKE l0 Sheets-Sheet 6 Filed Jar}. -'l4, 1942 /N vE/v'roH RUDOLPH 1f SCHON/TZER TTORNEYS.

March 6, 1945- R. SCHONITZER TREAD BLOCK CORES FOR ENDLESS TRACKS AND THE LIKE Filed Jan. 14, 1942 10 Sheets-Sheet 7 vE/v Ton HUDOL PH I. scHozvn-zsn I 7 My A T TORNEYS.

FIG. 26

Mai-ch 6, 1945- R. 1. SCHONITZER TREAD BLOCK CORES FOR ENDLESS TRACKS AND THE LIKE 1o Sheets -Sheet 8 Filed Jan. 14, 1942 /NVENTOR RUDOLPH I. SCHON/TZER TTORNEYS March 6, 1945- R. l. SCHONITZER TREAD BLOCK CO RES FOR ENDLESS TRACKS AND THE'LIKE Filed Jan. 14, 1942 10 Sheets-Sheet 9 Wm. m. mo 8 RUDOLPH I. SCHON/TZER A644, M AT-roR March 1945- R. l. SCHONITZER TREAD BLOCK CORES FOR ENDLESS TRACKS AND THE LIKE Filed Jan. 14, 1942 10 Sheets-Sheet 1O l lllllll llllllll lll Illlllllll lll I l I l ll //v VEN Tan 5000/. PH I SCHONITZER FIG. 4/

B Y 7 M 7? zfromvs s.

Patented Mar. 6,1945

TREAD BLOCK CORE FOR ENDLESS TRACKS AND THE LIKE i Rudolph I; Schon'itzer, Shaker-Heights, Ohio Application J anuary-14, 1942, Serial No.426,666

31 Claims. (01. s '1 0) This invention relates toendless tracks for vehicles such as tanks, tractors and the like.

More particularly, the present invention relates to improvements in the re-enforcing cores forthe rubber tread blocks of such tracks.

The type of tread block core with which the present invention is concerned is one having generally cylindrical passageways adjacent, and substantially parallel with the front and rear edges thereof, for the extension therethrough of cross rods by means, of which a, set of tread blocks,

containing cores of the-characterhere involved,

may be connected to form anendless track, the

laterally projecting end portions. of said cross rods being provided, on each side. of the track,

with suitable means which not only maintain the tread blocks in assembled, track-forming relation but which also cooperate in the driving and guiding ofthe track. Heretofore, it has been the practice to embed within the rubber-- of ,the tread blocks transversely disposedseamless tubing, for the reception of the cross rods,-

and spacing strips for such tubing, a type of tread block core which-has not been satisfactory; a The present invention thereforehas for its general object the pIOViSiOII of novel and improved cores for the rubber tread blocks of endless tracks, the re-enforcing character of said cores enabling rubber tread blocks provided therewith to successfully withstand the severeabuse to which such blocks are subjected in use in endless tracks, particularly the tread blocks of the endless tracks of heavy armored tanks and the like. 7 v w A more specific object of the present invention is the provision of tread block cores which;

are made ofsimple and inexpensive sheet metal parts, portions of which are constructed to provide cylindrical passageways through the tread blocks for the reception of the aforesaid cross rods, and which sheet metal cores, although of mounted upon'or carried by the laterally projecting ends of the cross rods-which extend through the blocks of said track being, omitted;

Fig.2 is a view, partly. invertical section and partly'in side elevation, of the track section of Fig. 1, the-view being on'the line 2--2, Fig. '1; Fig. 3 is a top plan view of the core. of one of;

the side tread blocks of the track of Figs. 1 and 2, the slightly projecting end portions of the two layers of rubber which are bonded to the oppo-z site faces of said coreto form a tread block' being indicated-in dot-dash lines;

Fig. 4 is a side elevational view'of saidcore; and showing in dot-dash lines the outer peripheriesof the two layers of; bonded thereto;

Fig. 5 is a cross sectional view of aside tread block containing the core of Figs. 3 and 4, the," view being in the plane of the line 5--5,,Fig. (it.

Fig. 6 is anexploded type of view, showing in sideelevationthree of thefour sheet metal members which make up the core of Figs."3, gland 5,.

the fourth and other outer member of the. core; not shown in Fig. =6, being identical with the outer core member shown at the top of Fig. 6;;

7 Fig.1? is a top-plan. view of the outerjcore member shown in Fig. 6, as viewed from theline.

l--1 Fig. 6, the view also being illustrative of the other outer core member not shown in Fig; 6;,

Fig, 8 is a top plan view of one .of. the two inner core members, as-viewed from the line 88, .Fig. 6. the view also being illustrative of.

the other inner core members, inasmuch as the two inner'core members are identical;

relatively light weight, have'surprisingly great strength, rigidity and ruggedness for the efiective re-enforcement of therubber of the tread blocks.

Other objects of the present invention-will appear from the following description of several tread block cores embodying said invention, ref: erence being had to the accompanying drawings, in which Fig. 1 is a top plan view of a section of one form of endless track having rubber tread blocks provided with cores embodying the presentin vention, the means whichco'nnect and which are Fig. 9isa cross sectional view of one of the;

outercore members, the view being on the line 9-9, Fig. 6; a

Fig. 10 is a view similar to Fig. 4, but showing a two piece core,which maybe usedjin either the side or the middle'tread blocks oi the track of Figs. land 2;

Fig; ll-isa view similar to Figs. 4 and 10, but, i showing a modified form of two-piece core, which maybeusedin the side tread blocks ofthe track of Figs. ;1 and 2;

Fig. 12 is a cross sectional view tread block containing the. core of Fig. 11,,the

view being in the plane of the line] 2l2 Fig. 11; v Fig. 13 is a top plan view of the core, of 'FigiJll,

and showing in dot-dash lines the slightly. projecting end portions of the two layers of rubbe which are bonded to. opposite faces of said core to form the tread block of Fig. 12;

Fig. 14 is a top plan view of the core oi. each of the middle tread blocks of the track oi Figs.

rubber which are.

'lin es;'

and 2, the slightly projecting end portions of the rubber layers of such block being indicated in dot-dash lines; I r

Fig. 15 is a side elevational view of the core of Fig. .14, and showing in dot-dash lines the outer tread block. containing the core; ofzFi'gs. 14andll)v 15, the view being in the plane of theline IB-l 6, Fig. 15;

Figs. 17 and 18. are detail views showing I slightly modified formof fastening meanszf sheet metal core members of the type show-11 i Figs-14, 15 and 16, the bottomtwo coremembgr of Figs. 15 and 16 having their bolt-receiving apertures slightly enlarged to receive=theanchor-+ ing portion of a lock nut-Fig. 17 being a VifiW.

partly in vertical transverse section and'partly' 20 core td-formsa-idrtread .block'being indicated in in side elevation, and Fig: l8sbeingna:horizontal:

cross sectional'vievc.on thejline I 8+- tB; Fig. 17; i Fig; 19: is w an explodeditypaof-view; showing in side elevation an .outer core member andan inner core member, saidtwo -memberseconstituting one 2 Fig.- 22 -is-a cross sectional view-pf'the:outer core member of 19; the-*view" being onthe line 22-22, Fig. 19; v

Fig. 23'isa crossflsectionalview of the inner core member ofFig. 19; ther viewbeing on'the line 2-3-23; Fi 1 1- Fig. 24is'atopplan-view'ofatransversely split ,40'

form-ofcore for a correspondingly split; formof alternatemiddletreadblock;the projectingend'portions 'of'the' two sections of "rubber which such block' includes being indicatedin dot-dash F,ig '25'is aisideelevationa-l;view=of the twosectionaljcore of. Fig; 24; and-showing-in dot-dash lines .thebuter peripheries of the-two-sections of rubber in'whichsaid core sections are-embedded;

Fig-2,6 is angendelcvational view of one of the two "duplicate core' sectionsof the core 'of Figs! 24,and-25 and-thesection of rubber-in which said core section-is embedded; t Q

Fig. 27 is ,anexplodedf-type-of view, showing in" side elevation j three of thefour sheet metal members of a-section'of the coi'e*of- Figs.'24 to 26;

inclusive the fourth and other outer-member 'of saidcore' section, not here: shown in Fig. 27, be-

ing identical with the outer coremember shown at'the top of thisview; I

Fig. 28 is a top plan view of the outermember 2 of Fig. 27; as; viewedfrom the line 28=-28,

Fig. 29'is -a' top plan -view of the adjacent "inner member of Fig. 27, as viewed from the line 29,29',, Fig. 27; the view 'also being illustrative of the other-inner member of the'core section, inas Fig.32 is a 'fragmentary view;' showing in side 75 elevation the front endportion of -'a' somewhat modified form of core, in which the front end flanges of the two inner core members are bent outwardly over the corresponding flanges of I the two outer core members;

Fig. 33 is a similar view of another modified form of core wherein thefront .end flanges of the four inner and outer core members are main tained in assembled relation by a sheet metal n h.

Fig; 34 is ,a fragmentary view, showing in side elevation the front and "rear end portions of a modified form of four-piece core, wherein each outer core member has one of its end flanges bent'over-the adjacent end flanges of the. other core members; v

35 is a .topplan view of a core'of a tread block which extends entirely across the endless track in'which-r it is used, the projecting front and. rear, edge portions of the layers of rubber which are bonded to the opposite faces of said dot-dash; lines; I

Figs 36 is afront elevationalview of the core ofrFig; 35, with a ipart of=such core. broken away to show interior construction; the :outerperipheries of'the two layers of "rubberwhich are bondedto the-opposite faces ;of: said'core-to, form a tread block being indicated in dot-dash lines;

Fig. 37'is a: view'partly in vertical'sectionand partly in side elevation lof'a treadblock contain-- ing-the core of Figs. 35 and 36, the view being on the line 37 31, Fig. 35;

Fig38 is=atop plan view of portions of "twov of i the tread blocks of Figs. 35; as assembled in end le'sstrackrelation; Fig 39- is atop plan view of "a modified form of core of a tread block of the'type whichextends across-the endless trackin which it is used; the projectingfront and ,rearportionsof'the layers of rubber which are bonded "to opposite faces of said "core toform said tread block-being indicated indot-dash lines; v

1. Fig; 40 is a' view of the core of Fig. 39, partly in front elevation and partly in vertical section, on the line 40-40 of Fig. 39, the outer peripheries of the two layers of rubberwhich are'bonded'to I r is not limited to the details of construction or the}- specific arrangement of parts herein illustrated ordescribed, as: the "invention obviously maytake other forms. It'also'is to beunder'stood' that the vphraseology or terminology herein em ployed is for purposes of description andnotof limitation, the scopefof the present inventionbe- I ing indicated by the-appendedclaims.

In'Figs. 1 and 2is;shown' a-sectionflof an endlesjs track which comprises three rows-of generally rectangular, longitudinally disposed rubber tread blocks, each containing a sheet metal core; em-' bodying the present invention, therebeing two laterally, spaced rows of sidetread blocks ln and arow of middle tread blocks I Lthe middle tread blocks being staggered with respect-to: the side necting means forms no part of the present invention. For the purpose of thisapplication, it is sufficient to point out thattwo such cross rods extend through the end portions of a middle tread block and through the side tread block end portions'which overlap said middle block. As a result, and as an examination of Fig. 1 will make evident, each middle tread block is connected to four side tread blocks (two on each side thereof), and each side tread block is connected to two middle tread blocks, inasmuch as each side tread block is overlapped by the end portions of two middle tread blocks. It may also be pointed out that the laterally projecting end portions 83 of the cross rods I2 not only carry the means which connect said rods in pairs but also carry parts which cooperate in the driving'and guiding of the track. However, inasmuch as said driving and guiding parts are not involved in the present invention, they have not been illustrated and no further reference to them will be made.

Inasmuch as the side tread blocks of the track of Figs. 1 and 2 are of identical construction, a description of the sheet metal core of one of such blocks will sufflce for all. Similarly, as the middle tread blocks H of said track are of identical construction, it will be necessary to de scribe the core of but one of those blocks, the cores of the side and middle tread blocks l0 and II differing somewhat, as will hereinafter more fully appear.

Each of the tread blocks 10 and II includes, as indicated .in the accompanying drawings, 'two layers of rubber between which the core is located, said layers of rubber being bonded or caused to firmly adhere to the outer faces of the core. Usually, the ground-engaging layer of rubber, herein designated by the reference numeral l4, has a somewhat greater thickness than that of the other layer of rubber, herein designated by the reference numeral l5, as here shown.- Referring now to the core which is used in each of the side tread blocks l0, it will be noted from an examinationlof Figs. 3 to 9 inclusive that said core is made up of fours simple and inexpensive sheet metal members of generally rectangular form in plan view, These four core members may, and here do, have the same width and length, and they are assembled in stacked relation, one above another, in a unitary structure, with their peripheries in alignment, as clearly shown in Figs. 4 and 5. Also as there shown, the width and length of the assembled core members substantially correspond to thewidth and length of the two layers of rubber l4 and I5 which are suitably bonded to the outer faces of the core, with the consequent re-enforcement of such layers of rubber throughout their entire area. For manufacturing economyand simplicity of assembly/the two outer core members l6 and I! (the top and bottom core members, as viewed in the drawings) are preferably identical and therefore interchangeable. Similarly, the two inner core members l8 and I9 are preferably identical and thus interchangeable, although it is to be understood that the sheet metal core for the side tread blocks Hlmay be of the form in which no two members are duplicates. I

As best shown in Figs. 4 and 6, each of the two inner core members l8 and I9 is provided adjacent each end thereof with a transversely disposed semi-cylindrioal corrugation 20. As a result, when the two inner core members are assembled in superposed relation, with'their cor transverse passageways 21 of cylindrical form are provided, one" for the reception of each ofthe two cross rods 12 which extend through each side tread blocks. If desired, and as here shown, the

diameter of'the core passageways thusformed may be somewhate greater than that ofthe cross rods I I2, in order that such passageways maybe provided with rubber linings 22 (see Fig. 2), although, obviously, said passageways may be made of such; size as to just receive said cross rods, as

' will be readilyunderstood;

, corrugations 20.

As here shown, welding is used to unite the two inner coremembers in superposed relation, the character of the welding and the location of the welded areas being such as to securely and effectively unite said members. Preferably, said inner core members are welded to each other along their overlapping end flanges 23, and along their overlapping middle portions between the ing of the two inner core members, the two end flanges 23 of each such member are here proa Vided with transversely spaced welding projections 24, and the middle portion of each such weldingprojections of the'other, inasmuch as the two inner core members here shownare of dupli. cate form, and to properlydistribute the welded areas, each such inner core member has its two sets ofwelding projectionsi24 suitably staggered,

' with a' corresponding staggering of its two sets of welding projections :25. As here shownfeach innercore member has one of its end flanges 23 provided with a row of two welding projections 24 and its other end flange provided with a row of three Welding projections 24. Similarly, each' innercore member has two welding projections 25 in one of its rows, and three welding projections 25 'in'its other row, all as clearly shown-in Fig. 8. Thetwo inner core members are so as-' sembled that unlike end flanges are brought together, the two projection flange of one'member lying opposite the three projection flange of the other. The transverse'spacing of the welding projections 24 and 25 ofueach inner core member is such that when said two core members are thusassembled, there isa'row of five transversely spaced welding projections 24 between each pair of end flanges 23 and two rows of five transversely spaced welding projections 25 between themiddle portions of such core members;

. Thettype of welding preferably used for the uniting of the two inner core members is the well known resistance welding, the welding projeotions'24 and 25 being melted in .the weldingoperation by the heat caused by the resistance of the electric current. Theqtwo inner. core members are thus united in a particularly effective and durable manner.

As indicated in Figs. 6 and 8, the welding projections 24 and 25 not only are spaced across the entire widthof the inner core'members but-are located as close as possible to the corrugations 20 therebetween, the effect of which is tomini U rugations oppositely disposed and matching, ltwo For the connection by'weld mizeany tendency of the, two innencore members to separate-or become disconnected evenunder severeconditions. of use; l

' Asabestqshownin .Fig. 4, the

two outer sheet metal'core'members lfiand li (the top and bottomv core members, as viewed-in Figs. 4 and are also provided adjacent their end flanges with transversely'dispo-sed corrugations of semi-cylindricali form, the corrugations 21- of such ,outer core members fitting over the corresponding co r,

nd':=the,=,-.outer:cor :m m e siare; hus-caused: o:

be rigidly and firmly united to; the twodnner core memberson'opposite'faccslithereofg Aszbest shown, in: Fig. -3, the" Welding projections 1 3,3 oi thegend flanges 32 of thegoutercore members are not only staggered with-respectto1 thewelding rugationslllof the two inner core members when gitudinal bridging of the two transverse corrugae tions ofeachof the outercore members, the layers of rubber l4 and I5 are efiectively 'reenforced between the corrugations of-said core members, as will be readily understood. If de-.

' sired, and as here shown (see'Fig; 4), the top wall of the rib 2B of each outer core member-may be provided with a longitudinally disposedchannel 29;which not only strengthens and rigidifies such core member but also, aids in the anchoring. thereto of the appropriate rubber layer M'or IS.

The two outer core members-wand are each projections 24 of the end'flanges 23 of the inner core members but also, are; located nearer-tothe aligned end edges of the two setsof flanges, namely, by adistance corresponding to the'thicm ness of {the metal of,whichthe,.outer core members are; made. l I v From, the foregoing description of the a core which is here used in -each of theside treadiblocks IUJ' Of the track-of-Figs; 1'and2-,:it:wi1l.beevident that said core, 'of' sturdy-box-likeaform' in :cross section, is well adapted to efiectively re-enforce the v,rubberlayers of .such block, and thusenable said block to successfully withstand the -=severe abuse towhich it is frequently: subjected in use; It will be equally evidentthat the four sheet metal members which comprise said: core; although of relatively-light weight and-, capableof being easily and cheapl made; are so1c-onstruct ed asto give them greatstrengthand'rigidity; so asto enable thetwo inner core members-ate receive thecross-rods I2 which extendatherethrough (thusmaking wholly unnecessary the use of seamless tubing and spacing strips therefor); and so asp-to enable; the layers .ofrubber to be efiectively anchored to the outer faces of the'outercoremembers, etc.;,,

provided, on opposite sides of its longitudinal rib 2B :and between its transverse corrugations 21, with fiat-side edge portions 3|, which contactthe middle portions of the inner core members adjacent their side edges when the two outer core membersware-assembled with the'two inner core members, on opposite faces thereof. As a result of the provision of the ribs 28, the core is of boxlike form in cross section (see-Fig; 5) andhence; one. which is of exceptionally strong and rugged character, as will be readily understood. The

- provision of the ribs 28 of the outer core members also-is of material assistance in the transverse anchoring to such core members of the layers of rubber l4-and.l5, and inasmuch as the end portions ofsaid layers of rubber extend around the corrugations 21 of saidcore members totthe end flanges 32i'the'reof, as clearly shown in Fig. 4, a

longitudinal anchoringaof the layers of rubber to suchcore members is also effected. To bond or bring about a secure adherence of said layers of rubber to the outer faces of the'outer core members, any suitable means may be, utilized, such as the copper plating of such faces, for example. Inasmuch as the outer core: members 16 and l1ihere-shown are of duplicate form, no special care need be exercised in assembling-them with the two inner.- core members on opposite faces thereof. To maintain such assembly, resistance welding is here utilized, and for that purpose, the

front and rear :flanges 32 of the outer core members; and the'flatgside edge portions 3| thereof,

are provided with welding projections, there being four welding projections 33 spaced in a rowalongeach of the end flanges 32. and two welding projections 34 spaced along each of the side'edge portions 3|.- In'the welding operation, the weldingxprojections 33 and 34 are melted by the heatcausedbyttherresistance of the electric current;

If desired, howeventhe core of-the side tread blocks lltmay be, one which consists of but-two sheet metal members, suchas the coreillustrated in Fig. 10. Inasmuch as the two duplicate members Iliav and |9a of the coreofFigclo are iden-- tical with, andare united in stacked relation by welding in the same manneras; the two-dupli cate inner. coremembers l8-and l9 aofithe core illustrated in Figs; 3' tot-inclusive and-heretofore described, no further-descriptionof the cor of Fig. 10 is believed to be necessary.- y I Another form of;two-'piece core which maybe used, in eachof thegside tread blocks-H], and which is of box-like-form in cross section, is -il lustrated:in Figs. 11 to l3,inclusive.- The-two duplicate sheet metal members36 and 3:1 of thi coreare substantially the-same'as the outer members l6 and-1 hot the core of Figs.- 3 to, 9 inclusive.- It will'be noted, however; particularly from a comparison of Figs.- 12 and5, that thelongitudinal ribs 38 of core members 36 and 31 are somewhat narrower than the corresponding ribs- 28;

of coremembers l6, and IT, and thatthetopwalls of-ribs38are not'channeled, although theyobviously may be, if desired. ,Italso will be, noted that although the contacting-side edge portions 39 of the core members 36 and,31"are,-united.by;

welding, (for which purpose, each of saidiside, edge portions is provided with ,a 'weldin IQIQ- jection 40); the front andrearend; flanges-:41: of such members are-connectedby bending; one of the end-flanges of each member over the-;ad-

jacentend flange of the othenmember; a: type;

of inter-lock whicheffectively-prevents; of course; endwise separation ofsuchmembers; As to this form'of core, no;further description-isbelieved to be necessary.

Referringnow; to the core of eachof'themiddle tread blocksil of thetrack ofFigsl' l and 2, it' will be'noted from an-examinationof'Figs;v 14-, 15-and 16 and Figs; 19 to 23 ,inclusiveithat :such' core comprises-four sheet metal ',members;:,there being two inner members 42 and 43:01? duplicate,

form and two outer members 44 and 45 of dupli-' cate form. It also will be noted that these four coremembers are each provided adjacent its end flanges with transverse, semi-cylindrical corrugations corresponding to the corrugations of the 5 members of the core of Figs..3 to 9 inclusive, and that the two corrugations of each of the outer core members 44 and 45 are bridged by a centrally disposed, longitudinally extending rib 46 which differs from the ribs 28 of the aforesaid 10 core only in that its top Wall is not channeled, although it obviously may be. Instead of being flat, as are the middle portions of the inner members l8 and I9 of the aforesaid core, the middle portion of each of the inner core members 42 and 43 is provided with a centrally disposed, longitudinally extending rib 48 of semi-circular cross section (see Fig. 16). As best shown in Figs. 15 and 19, the ends of the rib 48 of each inner core member merge with the side walls of '20 block comprising a layer ofv rubber I5, an outer 2.30

form illustrated in'Figs. 17 and 18 may be used incore member 44 and an inner core member 42, and the outer or ground-engaging section of each such block comprising a layer of rubber I4, an outer core member 45 and an inner core member 43. As will hereinafter appear, the two core 35 As shown in Figs. 19, 20 and 22, the front and .40

rear end flanges of the outer core member 44, and the flat side edge portions 5| thereof, are provided with welding projections 52 for the welding of such core member to the inner core member 42 in a, rigid sub-assembly, the type of welding used being preferablyresistance welding. In a similar manner, the outer core member 45 and the inner core member 43 are welded together in a rigidsub-assembly. By copper plating the outer faces of the outerucore members 5 44 and 45, or by the use of any other suitable means, the layers of rubber I4 and I5 are bonded or caused to securely adhere to such core faces, thereby uniting each core sub-assembly with its layer of rubber, as will be readily understood. For releasably connecting the two core subassemblies and their respective layers of rubber, four bolts 53 are here utilized, two for each set of end flanges, said flanges being provided, of course, with suitable apertures 54 for the reception of such bolts. As shown in Figs. 14 and 15, but more clearly in Figs. 1 and2, the recessed heads of the bolts 53 lie within suitable recesses 55 at the corners of the layer of rubber 15 of the inner block section, said recesses affording convenient covers 5! for said nuts and the projecting ends of said bolts, said covers being of such cross sectional shape and size as to prevent the turning of the nuts therein. As best shown in Fig. 14, said covers are provided with transversely disposed,

connected to the outersurfaces ,of'the end flanges of the outer coremember, 4 5,said cover flanges,

if desired, being welded to the end flanges of said core member during the Welding operation by which such core memberiand the inner core memberg43 are rigidly united in a subassembly. If desired, and as here shown, each of-the nuts 56 may be provided with a short treaded extension 59 of reduced size and of slightly elliptical shape,.the binding'of the threads of such extension with those, of the bolt 53 extending through said extension producing. suflicient resistance to prevent undesired unloosening of said bolt, as will be readily understood. I

From the foregoing description of the longitudinally split core ofv the correspondingly split middle tread blocks, l I, it will be evident that such core, of double box-like form in cross section, is well adapted for itsintended purpose. It also .will be evident that the simple and inexpensive sheet metal members of such core are of exceptionally strong and sturdyconstruction, and are unitedinto two rugged sub-assemblies, which are releasably connected in a particularly effective and durable manner. Moreover, the longitudinally split form of the middle tread blocks ll enables them to be readily applied to and removed from an endless track in thefield, if and when necessary, as will be readily understood.

If desired, nutsand sheetmetalcovers of the the releasable connection ofthe two core subassembliesjust described inplace of the nuts 56 and the sheet metal covers 5l. If that is done,

the bolt-receiving apertures, 54 of the rigidly united end flanges of the core members 43 and 45 will have to be somewhat enlarged, in the manner shown in Fig. 17, for the reception of the inner tubular anchoring portion 60- of the lock nut-6| of Fig. 17. As there shown, the aperture 62 in the end flange of the inner core member for, the,

reception of the bolt 53a is somewhat larger than the bolt-receiving aperture 63 in the end flange of the outer core member, in order that the inner end of such nut anchoringportion may be peened or headed over the flange of said outercorememe ber for the anchoring of such nut. As best shown in Fig. 18, the aperture 63 of thefend flange of the outer core member, and. that part of the nut anchoring portion which 1 extends through :said aperture, are of non-circular form, the effect'of which is to prevent turning of the nut, as will be readily understood. For bolt-locking purposes, thenutof Fig. 17 is here provided with a. threaded extension 65 corresponding to the extensions '59 of the nuts 56 of Fig. 15. The sheet metal cover 66, forthe protection of the projecting end of the .bolt 53a. from the layer of rubber in which it is to be located, is a simple cup-shaped member, having its upper end crimped into an annular groove of the nut extension 65, as shown in Fig. 17.

form of middle tread block containing a sheet metal core embodying the present invention.- As best shown in Figs. 24 and 25, this alternate form of middle tread block, including itssheetmetal core,is of transversely split form, the two sections thereof being duplicates. and being',disposed (as shown in Figs. 24 and 25) in abutting relation when in use. I a

As best shown in Fig. 25, this transversely split core comprises two duplicate outer sheet metal core members 68 and 69, eachof two-piece form, and two duplicate inner sheet metal corememoppositely extending flanges 58 which are suitably bers 10 and II, each of two-piece form. It will be evident from a corrrparison of figs; 25" and-I5, Figsa26 IS-endFigs- 3U and 22,- that the outer I core members 68- and G 9 ithe "same construction (except fortheir two-piece form)"=-as'thetwo outer core members and-45 0f the longitudinally split core heretofore described. It also willb'eevident froma comparison of -Figs.-'-25) and l5, Figs.-26 and 16 and Fig's z'i and-'19, that'the two inner core members 'lfl and 1 I differ in construction from the-twoinner members 42- and- '43 of said longitudinally' -split core on'l'yinthe character of their centrally disposed, longitudinally extending ribs 12 (thetwo part form' of said innercore members I0 and H, of course, being excepted); Asbest shown in Figs. 25, 27 and 29, the-ends-of the ribs 1 TZ-oftheinnefi CGre' membersand H do not merge intothe sidewallsof theirtransverse corr'ug'ations' (askiothe 'hollow ribs 48 0f the inner core members-Hand) but terminate in spaced relation thereto; and --furthermore, i the width J of saidribs l2 is such that their sidewalls; as well 'astheir top walls; engage'the corresponding walls of the ribs -1 3-of the'outer core members and 69.

For the rigid connection in stacked relation of v the four core "parts of '--each-,se'ctionof thistransversely split core, '----welding is here utilized,. the welding being preferablymfthe resistance type. For the connection of the two inner core parts part is 'providedalongfits-end flange with engaging op'posit e facesiofisaid tinnerccore: par-ts,

asishown; Y

' Forlthe formation of atread 'block'sectiomeach suchassembly of core'iparts has: suitably bonded alternate form of middle tread *block;it=will -be evident that such core, like those 'heretofore:;described; is well suited for the effective re-enforcement of 1 such tread block. "Each: of a the: sheet metal members of said core, ='althoughtof simple and inexpensive construction and a of relatively light weight; possesses great 'strengtlrand rigidity, and when united to form atwo sectional core,

afford the type ohm-enforcement 'required for a: tread :blo'ck'of' thischaracter. "Inasmuch as the two cross rods 12 which extend." through :this

tread block (one'through eachblock section): are

twowel'ding projections 16 i and-across thespace 7 between its transverse corrugation and the closed end of its rib portion 12 with twq welding pro- -jec'tions l1. During the welding -"operation;- these projections are melted by the heat caused by the resistance yor the electric current, with the consequent rigid connection of the two core Parts,

as mll-be'-"readi-ly understood. As -hereto'iore pointdoiltfitheinner core members 10 and I I I5 are of duplica form, and-in' order to properly distribute aiid -spa'ce the welded areas of -each connected pair -'ofparts thereof, the two welding projections '16 along me o'f the end 'flange l :of each innercore' mem ber- 'ar staggeredwith respect to the twowlding'prbjections l6 along the other efidflange' thereof L Similarly, the two "welding projections ll-adjacent one of the transverse corrugations df'each {inner core member are staggere 'wi'tn're'sp'ect tothe' two 'welding proconnected; at their end portions 1.3,:the' *ltwo block sections are tightly held together 'in theiabutting relationship-shown inFigsmZ. and 25, and any tendency of ablock section to turn: about its "cross rod is effectivelyresisted. l

Inasmuch as the c'ross rods l zfsmust'be' pushed endwise through the transverse passageways of the two :sections of:' the transversely 1 split tread 'je'tio'ns "adjacent the "other transverse corru gation thereof. Asa result,the two-inner core parts of ea'chcore section 'are'rigidly unit'edby a of 'iour equally 's'pacedwe'l-ding" projectionsls andby a row' brrour equally "spaced' weldingprm 'cti'ohs 1T, as"indi'cated'in"Fig."24 and as will be readily "understood. 1

Forthe c'onnectionto eachfpair of inner core parts, on jo'p'po'sit'e' faces thereof, or a pair of outer core partsfweidmg is here used. "Forsu'chf pur- 'pose; each outer core'part is"'provided along" its end flange 18 With'Weldihg projections"!!! (five, 'as' here shown) and across "the t'0pWal1 of "its ri'b' portion 73, 'adjac'ehtthe' "free edge 80 thereof, with'weldi'ng projections? I "own; as here shown) Each such core part isalso'providedjwitha" welding projection B2jon each of'the two flatportions 83 thereof which lie on opposite sides of its'longituglinal rib' portion 13,- as bestshown in'Figsy28 and 30. By the use of these weldingprojections '19, 8! and 82, which-melt by the heat caused by the resistance of the electric current in-the weldi-ng operation; each pair of inner core parts has unitedtherewi-th; in arigid-and unitary-assembly, a pair of cutercoreparts, said outer 'core' parts block of Figs. 24 to 29 inclusive-and inasm uch as the end portions f of said cross rods -may, and

*40 preferably do; fit tightlyin thecorresponding passageways'of the side-tread blocks-'(thelatter passageways being rubber lined, if desired) ,replacement in the field of se'ctio'ns "of the treadi b'locks of'Figs. 244120 29 inclusive can best-be made:by the use -'of factory: assembled replacement-units.

Each such-*- unit will I' comprisei. a cormected pair of cross :rods 2 Qn -Whi'chJare'. mounted two side tread blocks :and two middle t-read' block -sections, said sections" constituting;-when' Iin': a track, the adjacent sectionsliof- :two adjacent imiddle .-tread blo'cks. damaged one can be easily made in the field-wall as-will be readily-understood.

.31 In Figs. 32, -33wan'd 34 :are i1lustrated=modified arrangements for un'iting the end-flanges bf cores which comprise four core members. In "Figfl32, the contacting end -fian'ges -85 of the *two inner 'sheet metal core --members are bent around the adjacent end flanges i of the outer core members. It is thus nec'essary to unite by-"weldingor other suitable means only the end flanges of the: inner core members tomaintainthe founcore -members in assembly; In 'Figfi33, the 'endflanges ofrall 'four' core "members are'imaintained in stacked relation by welding thereabout asheet metal locking'strip '86 of channel-shaped 'crossrsecti'on. In mgr-34,? thetwo duplicate outer'core :members 1 each has an assembly-maintaining end flange, the rear end flange 8] ;of -the outer core member -81abeing: bent" around; the rear end -flange:of;the outer core member BBa'andthe rear end'l-flan-ges ofthe two inner core members; :and the frontend flange "8810f the outer corernember M r-being bent around the front end flanges-of theoutercore member 81a and 'the front end The substitution of such a unit fora The'core of'Figs. 35to 37 inclusive is therefore flanges'of the two inner core members. With such a'connectionof theend flanges of these four core members, no welding or the like is neoes sary.

If desired, the end flanges of the core membersof the side tread blocks I 9 and the end flanges of the transversely split coremembers of the alternate form of middle tread block may be connected by any of the arrangements shown in Figs132, 33 and 34. The arrangement of Fig. 32 (but not those of Figs. 33 and 34) is also suitable for the end flanges of the two core'sub-assemblies of the longitudinally split core of the middle tread blocks I [if the connection of the end flanges of the two middle core members is eflected by bolts and nuts or other fastening means of-the releasable or detachabletype, rather than bywelding, inasmuch as the two core subassemblies of the middle tread blocks ll must be capable of convenient separation, as heretofore pointedout. I In Figs. 35 to 37 inclusive is shown a tread block 90 which is transversely disposed in the endless track in which it is used, the track-being formed by a series of suchblocks arranged sideby side, as indicated in Fig. 38, with each block having a length co -extensive with the width'of the track. Like the tread blocks heretofore described, the tread blocks 90 also are adapted tohave extended therethrough suitable cross rods (not shown) by which they are maintainedin endless track'form, the projecting end portions of said cross rods being connected in pairs by means not necessary to be here illustrated or described.

As best shown in Fig. 37, the layers of rubber l and M of the tread block 90 are separated by a sheet metal core embodying thepresent invention. As such view clearly shows, said core comprises six sheet metal members, there being a pair of duplicate outer members, a pair of duplicate inner members, and a pair of duplicate members 9| of generally channel-shaped cross section, said channel core members being disner, as the corresponding members of the core of v the side tread blocks Ill. The only structural dif-' ference therebetween is that each of the outer members of the core of the tread blocks 90 isprovided withtwo transversely spacedchannels 94; rather than with a single channel (the channel of each of the outer members of the core of the tread blocks [0 being numeral 29). 1

As clearly shown in Figs. 36and 37, the oppositely extending flanges 92 of the generally channel-shaped members 9| of the core of the tread blocks 90 are provided with suitable depressions 96 to receive the channels 94 of the outer members of such core. It also will be noted from an examination of Fig. 35 that said outer core membersare providedwithwelding projections 91 for use in uniting to such members the flanges 92 of the channel coremembers 9|. From an examination of Figs. 35 and 36, it will be noted thatthe channel core members! are of slightly less length than that of their associated core members. i i i a designated by the reiere'nce well suited for the re-enfo'rcement of a'ftread block having a length coincident with the track I whichblock has a length co-extensivewith the width of'suoh track.

The tread block 98, like thesother tread blocks heretofore described, contains a core embodying the "present invention. As best shown in Figs. 39 e and 40, the core of this tread block'98 comprises four sheet metal members, there being apair of duplicate outer core members, and a pair of 'duplie cate inner core members. As will be evident from a comparison of Figs. 41 and 37, the twoiinner members of the core ofthe tread block 98 are of the same construction as the two inner members of the core of the tread blocks 90. It also will be evident from an examination of Figs. 39, 40 and I 41, that the two outer membersof the core of the tread block 98 difier from the inner members of such core only by the two'laterally spaced ribs 99 with which such outer core members are provided between their two corrugations. From an examination of Fig. 39, it will be evident that the four members of the core of the tread block 98 are united by welding, the front and rear flanges of such core members, and thoseportions thereof lying between their corrugations, being provided with suitable welding projections for-such pur- I pose; As best shown in Fig. 40, the ribs 99 of the outer core members are of generally semi-circular cross section.- When arranged in matching pairs, they form generally tubular re-enforcement parts which afford great strength against torsional stresses,-as will be readily understood.

No further description of the core of the tread block 98 is believed to be necessary, although it may be pointed out that such core enables the layers of rubber of such block to have material thickness (between the corrugationsof such core) throughout substantially the entire length of the block. This produces substantial cushioning'efe feet b'etweenthe core corrugations, readily understood. Y

As heretofore pointed'out, the outer faces of as will be I the tread block cores here illustrated and dc scribed may be, and here are, copper plated'to enable the rubber or the tread blocks to be bonded to such corefaces. Inthe copper plating of said core faces, which takes place after'the, cores. are formed, the use of several solutions is necessary, and in order to avoid any liability of the co-mirigling of such solutions, by the travel OfthQCOIBS from one solution to another, the four 'member cores here illustrated are provided with suitable drainage apertures and/or drainage passageways, as Willhereinafter' ap-' pear. No drainage apertures or drainage pas;

sageways are necessary in thetwo member cores here illustrated (the core of Fig. 10 and the core of Figs. 11- to 13 inclusive), inasmuch as from before they rcach the next solution into though either :such apertures or such tpassageunited with the two inner core 'members -liil and I9) to readilydrain into the open e'nded transverse passageways 2 I 'formedby the' corrugations 20 of the inner-coreymembers. The draini-passageways of this core are formed the flat side portions 3| of the outer =coremembers46 and I1, there being: one such drainage :passagew'ay in each=such portion :31, as clearly-showndn 3 'and 7i Inasmuchas these drainage passageways-IOI communicate at their innerends with the-hollows of the ribs-2 8 of :theouter core members, and areo-pen at their outer erids, anysolution in/the hollows-of such ribs will readil-y drain therefrom through-suchflpassageways; As here tofore pointed out, the use of both-the drainage apertures I and the drainage passageways 41H are not necessary, although thezuse-of both en? ables the core to bereadily drained. in any: posirtion in which it is suspended during its travel from one solution to the next as will bereadily understood.

As will be evident from-an-examina-tionofFigs;

14, andflG and Figs. 1 9 -to;-23inclusive-the longitudinally split core of -the middle tread blocks 'II is provided with dr'ainage apertures I62 and drainage passagewayslila't identical with those ofthe core of the side tread blocks 40. a result, no further reference to the drainage apertures and the drainage passageways ofsth'e, core of themiddle tread. blocks H-isneeessary;

"In the transversely split core of the alternate form of middle tread block illustrated in Figs. 24

to '29 inclusive; a drainageapertureIM is provided in the transverse. corrugation of r each part of the'two inner core members 10 --and "H. As best shown 'in such apertures communicate with the ends of the hollow-ribs 13' of-theouter core members '68 and "69 and thus-permit any solution in the hollows of said ribsto be drained therefrom. If desired'and as here shown, the

top wallo'f the rib "I2 of each of the inner core memb'ers may be provided with a drainage spas sageway I65, the provision of the passageways establishing communication between. thosepore ti'ons ofthe hollow of each rib 'I 3.--wl 1ic hlie on opposite sides. of the rib 12 therein, as- ,-wi1lbe evidentfrom an examination of Fig. -2 5 In the core of the tread block 90' of Figs. 35- to 37 inclusive, th'ree drainage apertures liliirare provided in each of the corrugations of the inner core members for the drainage of the hollows of the channeledribs of the outer'core members;

Drainage passages IIJ'I- also-may be .provided, if

desired and as here shown, in the base portions I108 oifthe generally channel-shaped-core mem bers B I, the result of. which is to eestablish com afar-1:157: I

' draining the'ribs 9 9" of j: the oute'r core membersl If: desired; and-as hereshovvn; drainage apertures I III-also may 'beeprovidedin: the outer core I members, between their corrugations,. to permit the escape of "any solutionswhich maiy find-' its way between those portions of ime inner core mem bers :which lie b'et-wee'n their corrugations and con'esponding por ions'ofthen-outer core members.- I a on heretofore pointed'outf: the outer members I6 and of the core 'of Figs; .3to"9inclusive=have their front and r rear flanges 32 'spot welded to the corresponding flanges 2-3of the inner i'nembers I 8 aud t-90f said core. =In-order to supplementthespot-welds which thus unite sa id fianges,

the -corrug-a-tions "21 of the --outer core m'embers I 6- and I I may be, and here aregsuitably brazed to the correspondingcorrugations of y the, Y inner core members I8-= and +8. For purposes 5 ofsuch brazing; the outer: corrugations L l/are -.provid ed .with suitable apertures III providingyaccess to the inner corrugations 2 U and: receiving more 701 less of the brass or spelter -I|-2 utilized in the braaing -operation, said' apertures being located, preferably, as close as possible to; the "front and rear flanges 3-2 oi the outer core, members.

v though the number ofapertures III with which to enable them to be spaced along the fulllen-gtheach corrugation 21 is providedmay besuch==as of said corrugation,- each such corrugation -2-'I is liere-provided with four such-apertures, two-adjacent each end of saidcorrugation, as H clearly shown in Eigsr3- and 7. i I

Also, if desired and as here showm the spot welds by which are united the two front flanges 23 "ancLthe two rear flanges '23 o-f the inner mem bers I8 and I 9=of the oorepiFigs. 3 -to -9;incl-usive may' be supplemented by further welding rot-such flangeasuch as -at the rear edges of the front.- pair of flangesand at thefrontedges of the rear pair pt fiangesas clearly-shownat I I 3 in' -Figs.- 3,. v '4uand'6. Such"additionalwelding; of- -ei-therthe ga or arc type, may extend the 'full -lengthof suchfflan ges or, if desired -onlyt along the end portionsthereof, as will be readily understood.

Supplemental welding like that-designated by the reference numeral-J43 may alsobe used, if

desired, in connection with the two members'of the 'core of Fig. 10, and in connection with the inner mem-bersof the cores of Figs. '24 I to #29 i'rr-s clusive, l ig.-32, Figs. Eto 138 inGluSiVe 13Ilfd*FigSm 39- to -4-1. inclusive. Similarly; the outer member's or the-cores of Figs. 24 'to' 29 inclusive, 'Figs..-35:

to 38 inclusive and Figs. 39120-41 inclusive may be provided with: apertures, likethosede'signated by theareferenee numeral-- H-I inorder thatsuch:

outer core members may berbrazed'to :the: inner: core members 7 with iwhich "they iiare associated,

' all aswill be readily-understood;

e'nt invention will be readily apparen't't'o those skilled in the art to 'whichi t relates; M hatl'claim isz:

"1 A core -for'the 'rubber tread blo'ck-6 :dmend less- -trackof tliefitype' in which the tree of suchtrackehavecross iods extendi n tera y therethrough;.said core comprisingenpan f sh et metal member's' rig'idlyconnected instacldd rela munication between those portions offthe-hOllow ofv each rib or the-outer ooremembers which are disposed on opposite-sides of the core member 91 therein.

In the tread block core of Figs. '39 to 4 1 inelusive, drainage apertures- 409 are-:prov idedi irr-the corrugations of. the inner core members for extending and lateral disposed tion. I nd: provided. adjacent" each df tlie 'frb'nt andsrearr edgesath'ereofl wi-th a pa -f oppositely rugations coextensive-- Further .-f;eatures and advantages 1 of. the pres w re 'tbhir'ig corith the length ofsiibh" edges; iea'chep'air of? such sms-toning eonugatiens providing;Earl-laterally disposed 'eassag'eway be tween said core members for a correspondingly disposed track cross rod, the two passageways being in generally parallel relationship, the front passageway being closed along its front side and the rear passageway being 'closed along its rear side, the two core member between the front and rear passageways being substantially in abutting relationship.

2. A core for the rubber tread block of an endless track of the type in which the tread blocks of such track have cross rods extending therethrough, said core comprising a pair of sheet metal members rigidly connected in stacked relation and provided with overlapping flanges at each of the front and rear edges thereof, said pair of connected core members also being provided adjacent. the overlapping flanges at each of the front and rear edges thereof with a pair of oppositely extending matching corrugations coextensive with the length of such edges, each pair of such matching corrugations providing a passageway between said core members for a track cross rod.

3. A core for the rubber tread block of an endless track of the type in which the tread blocks of such track have cross rods extending therethrough, said core comprising a pair of sheet metal members arranged in stacked relation and provided at the front and rear edges thereof with rigidly connected overlapping flanges, said pair of connected core members also being provided adjacent the overlapping flanges at each of the front and rear edges thereof with apair of oppositely extending matching corrugations coextensive with the length of such edges, each pair of such matching corrugations providing a pas sageway between said core members for a track cross rod.

4. A core for the rubber tread block of an endless track of the type in which the tread blocks of such track have cross rods extending therethrough, said core comprising a pair of sheet metal members arranged in stacked relation and provided adjacent each of the front and rear edges thereof with a pair of oppositely extending matching corrugations coextensive with the length of such edges, each pair of such matching corrugations roviding a passageway between said core members for a track cross rod, said coremembers being rigidly, connected by the connection of those portions of each member lying on opposite sides of each of the corrugations thereof to the corresponding portions of the other member.

5. A core for the rubber tread block of an endless track of the type in which the tread blocks of such track have cross rods extending therethrough, said core comprising a pair of sheet metal members rigidly connected in stacked re lation and provided in the region of each of the front and rear edges there-of with a pair of oppositely extending matching corrugations coextensive with the length of such edges, each pair of such matching corrugations providing a passageway between said core members for a track cross rod, at least one of said core members being provided with a strengthening rib extending between andsubstantially normal to the corrugations thereof.

6. A core for the rubber tread block of an endless track of the type in which the tread blocks of such track have cross rods extending therethrough, said core comprising a pair of sheet metal members rigidly connected in stacked relation and provided in the region of each of the front and rear edges-thereof with a pair of oppositely extending matching corrugations coextensive with the length of such edges, each pair of such matching corrugations providing a passageway between said core members for a. track cross rod, said core members also being provided between and substantially normal to the two pairs of corrugations thereof with a pair of, oppositely extending matching ribs.

'7. A core for the rubber tread block of an endless track of the type in which the tread blocks of such track have cross rods extending therethrough, said core comprising a pair of sheet metal members rigidly connected in stacked relation and provided in the region of each of the front and rear edgesthereof with a pair of oppositely extending matching corrugations coextensive with the length of such edges, each pair of such matching corrugations providing a passageway between said core members for a track cross rod, at least one ofsaid core members being provided with a strengthening rib extending substantially normal to the two corrugations thereof and having its ends merging with the side walls of such corrugations.

8. A core for the rubber tread block of an endless track of the type in which the tread blocks of such track have cross rods extending therethrough, said core comprising a pair of sheet metal members arranged in stacked relation and provided with flange portions at each of the front and rear edges thereof, said pair of core members also being provided adjacent the flange portions at each of the front and rear edges thereof with a pair of oppositely extending matching corrugations coextensive with the length of such edges, each pair of such matching corrugations providing a passageway between said core. members for a track crossrod, thefront and rear flange portions of each-of said core members, and the side edge portions thereof between its corrugations, being in contacting relationship with and being rigidly connected to the corresponding flange and side edge portions of, the other core member.

9. A core for the rubber tread block of an endless track of the type in which the tread blocks of such track have cross rods extending therethrough, said core comprising a pair of inner sheet metal core members rigidly connected in stacked relation and provided in the region of each of the front and rear edges thereof with a pair of oppositely extending matching corrugae tions coextensive with the length. of such edges, each pair of such matching corrugations providing a passageway between said inner coremembers for a track cross rod, and'a pair of outer sheet metal core members rigidly connected with said inner core members and disposed on op-' posite faces thereof.

0. A core for the rubber tread block of an endless track of the type in which the tread blocks of such track have cross rodsextending therethrough, said core comprising a pair of innersheet metal core members rigidly connected in stacked relation and provided in the region of each of the front and rear edges thereof with a pair of oppositely extending matching corrugations coextensive with the length of such edges, each pair of such matching corrugations providing a passageway between said inner core members for a track cross rod, and a pair of outer sheet metal core members rigidly connected with said inner core members and disposedon opposite faces thereof, one of said outer core members being provided with a strengthening rib extending substantially normal to the cor rugations of said inner core members.

11. A core for the rubber tread block or an endless track of the type in which the tread locks of such track have-cross rods extending therethrough, said core comprising a pair of inner sheet metal core members-rigidly connected in stacked-relation and provided in the region of each of the front and rear edges thereof with a pair of oppositely extending matching corrugations coextensive with the length of such edges, each pair of such matching corrugations providing a passageway between said inner core members for a track cross rod, and a pair of outer sheet metal core members rigidly connected with said inner core' members and disposed on opposite faces thereof, one of said outer core members being provided in spaced relation to its side edges with a strengthening rib extending substantially normalto the corrugations of said inner core members. 12. A core for the rubber tread block of an endless track of the type in which the tread blocks of such track have cross rods extending therethrough, said core comprising "a pair of inner sheet metal core members'rigidly connected in stacked relation and provided with spaced pairs'of oppositely extending matching corruga tions extending generally parallel withthe front and rear edges of such core members and coextensive with the length of'suchedges, each a pair of such matching corrugations providing a endlesstrack of' the type in which the tread blocks of such track have cross'rods extending therethrough, said core comprising a pair of inner sheet metal core members rigidlyconnected instacked relation and provided with overlap ping fiangesat each of the front and rear edges thereohsaid pair of inner coremembers also being provided adjacent the fia'ngesat each of the front and rear edges-thereof with a pair of oppositely extending matchingcorrugations coextensive with the length'of such edges, each pair of such matchingv corrugations providing a passageway between said inner core members for a track cross rod, and a pair of outer sheet metal core members rigidly connected-With said inner core members and disposed on-opposite faces thereof, said 'outer'core members being provided at their front and rear edges withiflanges contacting the flanges of said inner core members and'also being provided with strengthening ribs extending generally normal to-the corrugations of said inner core members,

14..A core for the rubber: tread block of i an endle'sstrack-of the typein which the tread blocks ofrsuch tracli have cross rods extending therethrough, said core comprising a pair of inner. sheetmetal core" members rigidly connected sheet metal core members rigidly connected with instacked relation-andprovided in the region said inner core members and disposed on opposite faces thereof, said outer'core members being provided with strengthening ribs extending generally normal to the corrugations of said inner core members, the top wall of at least one of said ribs being longitudinally channeled.

15. A core for the rubber tread block of an endless track of the type in which the tread blocks of such track have cross rods extending therethrough, said core comprising a pair of sheet metal core members rigidly connected in stacked relation and provided in the region of each of the front and rear edges thereof with a pair of oppositely extending matching corrugations coextensive with the length of such edges, each pair of such matching corrugations providing a passageway between said core members for a track cross rod, and a supplemental sheet metal core member rigidly Connected in stacked relation with said first mentioned core members, said supplemental core member being provided with a strengthening rib extending generally normal to the corrugations of said first mentioned core members.

16. A core for the rubber tread block of an endless track of the type in which the tread blocks of such track have cross rods extending therethrough, said core comprising a pair of sheet metal core member rigidly connected in stacked relation and provided in the region of each of thefront and rear edges thereof with apair of oppositely extending matching corrugation coextensive with the length of such edges, eachpair of such matching corrugations providing a passageway between said core members for a track cross rod, and a supplemental sheet metal core member rigidly connected in stacked relation with said first mentioned core members, said supplemental core member andoneof said first mentioned core members being each provided with a strengthening rib extending generally normal to the aforesaid corrugations.

' 17. A core for the rubber treadv block of an endless track of the type in whichrthe tread blocks of such track have cross rods extending there through, said corecomprisingawpairvof sheet metal core members rigidly'connectedin stacked relation and provided in the region of each-of the front and rear edges thereof with a pair of oppositely extending matching corrugations coextensive with the-length of such edges, each pair of such matching corrugations providing a passageway between said core members for a track cross rod, and a supplemental sheet metal core member rigidly connected in stacked relation with said first mentioned core members, said supplemental core member being provided with a strengthening rib extending generally normal to the aforesaid corrugations and one of said first mentioned core members being provided with a correspondingly extending strengthening rib disposed within the rib of said supplemental core member. 1 v

18. A core for the rubber tread block of an endless track of the type in which the tread. blocks of such track have cross rod extending therethrough, said core comprising a pair of sheet metal core members rigidly connected in stacked relation and provided in the region of each of the front and rearv edges thereof with 'a'pair of oppositely extending matching corrugations coextensive with the length of such edges, each pair of such matching corrugations providing a passageway between said core members for a track

Images