AU3254500A - Linkage type crawler and metallic core therefor - Google Patents

Description

P/00/011 28/5/91 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT u r Name of Applicant: Actual Inventors Address for service is: FUKUYAMA RUBBER IND. CO. LTD YUSAKU KATOH and TATSUYA NORITOH WRAY ASSOCIATES 239 Adelaide Terrace Perth, WA 6000 Attorney code: WR Invention Title: "Linkage Type Crawler and Metallic Core Therefor" The following statement is a full description of this invention, including the best method of performing it known to me:- The present invention relates to rubber crawlers, to be installed on the undercarriage of movable construction machines, earth work equipment, etc., and metallic cores for such rubber crawlers.

PRIOR ARTS Although steel crawlers have been mainly used for movable construction machines, etc., rubber crawlers are *oo.

also becoming used popularly in recent years. With steel crawlers, since the upper face of the track link becomes a 10 continuous rolling track, the vibration during travel oo•0 motion is small and there is no stretching in the circumferential direction or side-slipping in the width direction. Steel crawlers thus present the advantage that the crawler will not come off easily. Also, since the 15 mechanical coupling between links is strong, steel crawlers are excellent in durability. On the other hand, steel crawlers are loud in noise and poor in cushioning 2 properties and causes much fatigue to the operator and damage to the road surface.

Meanwhile, rubber crawlers are quiet in noise and good in cushioning properties and presents such advantages as lightweightness, ability to travel at relatively high speeds, etc. However, since the mechanical strength of rubber crawlers is less than that of steel crawlers, rubber crawlers presents such disadvantages as being poorer than steel crawlers in mechanical strength, tending to stretch in the circumferential direction or twist in the width direction and thereby coming off upon application of abnormal external forces, and giving rise to vibration during travel motion due to the loop track surface being discontinuous.

Japanese laid-open patent publication No.Hei-4-71386 (Title of the Invention: Linkage Type Rubber Crawler), which was priorly applied for by the present inventor, discloses a linkage type rubber crawler in which the arrangement of a steel crawler is incorporated in a 20 conventional rubber crawler to thus remove the above disadvantages of prior rubber crawlers by incorporating the advantages of steel crawlers. Figs.8A-C show one preferred embodiment of such a rubber crawler with Fig.8A -3being a plan view (ground side), and Figs.8A and 8B being cross sections along lines B-B and C-C of Fig.8A, respectively. In the Figures, 15 is the rubber crawler body, 15a is a wing part lug, 15b is a central lug, 16 is a metallic core, 16a is a wing part, 15c is a curved part at which the rubber crawler body 15 is curved, 15d is a hole, 16b is a central part, which is formed as an indentation, 16p is a bolt hole, 17 is a track link, 17a is a window, 17p is a bolt hole, f and f' are a bolt and a nut, respectively, 18 is a reinforcing layer, and 19 is a link pin.

With this type of rubber crawler, the bolt holes 17p of a pair of track links 17 are aligned and bolted together with the bolt holes 16p at the central part 16b of the metallic core 16, which are embedded in the rubber crawler body 15, and the ends of each track link 17 are linked with a link pin 19 so that a continuous rolling track is formed by a pair of track links 17, that are linked at the inner circumferential side of rubber crawler 15. The vibration during travel is thereby reduced and the crawler is prevented from coming off.

Primary problems of conventional arts related to the invention are as follows.

That is, as shown in Fig.9, at the part where the linkage type rubber crawler loops around the driving wheel or idler wheel, the parts of the rubber crawler that are on the outer side of the line joining link pins 19 are stretched. Furthermore, the parts at which a metallic core 16 is embedded remain unstretched while the parts between the metallic cores stretched. Thus when the stretch at these parts become large, the fatigue due to repeated stretching accumulates and durability *is lost. With the invention proposed in Japanese laid-open patent publication No. Hei-4-71386, the part of rubber crawler body 15 between the metallic cores is protruded and curved toward the inner circumferential side of the rubber crawler as a curved part 15c to secure an allowance for stretching during looping and a reinforcing layer 18 is embedded in the rubber crawler body 15 to provide durability. However, since the reinforcing layer 18 does not stretch much, unless the curved part 15c is made nearly equal in height to the link pin 19, the rubber 20 material will stretch while the reinforcing layer remains S. unstretched, causing the tensile force to concentrate on the reinforcing layer and the reinforcing layer to become cut.

Also among the various types of work equipment, there are types in which a crawler runoff prevention guide or a rock guard is provided near the idler. Fig.10 shows a crawler device equipped with a rock guard 20 and onto which the rubber crawler body 15 described above has been installed. Fig.lOA is a side view and Fig.10B is the cross section along line Z-Z of Fig.lOA. Here, 21 is the body frame of the travelling equipment, 22 is an idler, 23 is a roller, and 24 is a sprocket. With such equipment, the curved part 15c may come in contact with the rock guard, etc. of the machine body when curved part 15c is curved to the position of link pin 19 and cause problems.

to solve problems, and it is therefore a primary object of the inveni-on to provide a linkage type rubber crawler that can be mounted various types of working equipment in a suitable marr s.

Another problem of conventional arts related to the invention is as follows. That is, as shown in abovementioned Fig.10, depending on the working equipment, the tip of rock guard 20 may contact the wing part 16a of the metallic core and prevent the installation of the crawler or disable travel upon installation.

-6e ven 1 made to lve such a problem, and it is another object of the invention provide a linkage type rubber crawler in which the parts of th ubber crawler between the metallic cores have durability again accumulation of fatigue and which can be mounted to various v ious types of working mqu ent in a suitable mBAnn rat all tim s.

Still another problem of conventional arts related to the invention is as follows. That is, since construction machines and earth work equipment must frequently travel over unprepared land with uneven travelling surfaces, scattered pebbles, etc., with the linkage type rubber crawler of Fig.8, pebbles, mud, wood chips, etc. tended to enter into the inner circumferential side through the holes 15d to flaw the link pin 19, damage the engagement of the sprocket with link pin 19, etc.

s still another-ubject uf L1i i timenbton to provi'de a linkage e rubber crawler that can cope effectively .em.

-th thc cabove problem.

Further problems of conventional arts related to the invention are as follows.

That is, the abovementioned linkage type rubber crawler is either an endless type or one that is divided into a -7suitable length. Figs.llA and B show such an example of a linkage type rubber crawler, which is divided into a suitable length, disclosed in Japanese patent application No. H ei-6-94043. Fig.llA is a perspective view while Fig.B is a cross section in the circumferential direction of the connected parts. As shown in these Figures, a metallic core 16 and a keep plate 25, with a bolt f protruding therefrom, are respectively embedded at the upper end part and lower end part of a semi-endless 'crawler, which is divided into upper and lower parts at positions where the metallic core is embedded. These upper and lower end parts are overlapped and joined by inserting bolt f of keep :plate 25 in bolt hole 16h of metallic core wing part 16a.

*.Since the linkage is made by bolt f nut f'I, etc. in this method, the joining work is not easy and repairs are required when a bolt becomes broken.

n attempts tolve such problems, and it is a further object of the inven to provide a linkage type rubber crawler that can be mounted various types of working DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE

INVENTION

-8- The present invention provides a metallic core embedded in a linkage type rubber crawler, in which a protruding lug is provided at the ground side, a pair of track links is attached to the center of the inner circumferential side, said metallic core comprising a central part and two wing parts on opposed sides of the central part, characterized in that an attachment means for attachment of each track link is formed at the central part, and the dimension (L3) of the central part in the extent between the two wing parts is made greater than the interval between outer faces (L4) of a pair of rock guards protruding from the body frame of a machine on which the linkage type crawler is installed.

The present invention also provides a linkage type rubber crawler having a metallic core as hereinbefore defined.

The invention also provides a linkage type rubber crawler comprising a rubber crawler body and a plurality of metallic cores as hereinbefore defined.

a oooo a *oao direc on of the swl -p ndiGulaz__t& e circumferential direction of the rubber crawler body, lug are provided at the ground side of the rubber crawler body, pair of track links is attached to the upper face of the ce tral part of the metallic cores, and front and rear track 1 ks are linked in a mutually bendable manner to form a trac comprised of a pair of continuous track links, said li age type rubber crawler being characterized in tha the rubber crawler body is made continuous in the circu erential direction at both sides outside rock guards protru dng from the vehicle body frame and is formed into a curved pa t, which curves towards the inner circumferential side, at parts between adjacent metallic core wing parts, and t e width (Ll) of the metallic core wing part, to be emb dded in the linked rubber crawler body, is made shorter t n the width (L2) of parts of the metallic core central par at both outer sides of the bolt holes for track link attach ent bored in the central part of the metaI ic co-T S. 20 -4tR, he embedded metallic core may take on a flat shape or a shape in which the central part is indented with respect to the t n wing parts.

V't t\J \N A With this invention, a metallic core, which is comprised of wing parts, which extend to the left and right, and a central part, which is indented with respect to the wing parts, has an attachment means, such as bolt hole, for attaching the track link formed at the central part, and for which the length (L3) of the central part is made larger than the interval between outer faces (L4) of p a pair of rock guards protruding from the body frame of the travelling equipment (L3 L4), may be used as the metallic core embedded in the linkage type rubber crawler.

The ff c g of the ccond inventionn dchnrihd h hpvc are aiolws.

That is, by making the rubber crawler body continuous in the circumferential direction at both sides outside the rock guards and into a curved part, which curves towards .the inner circumferential side, at parts between adjacent metallic core wing parts, and by making the length (L3) of the central part of the metallic core, which is indented with respect to the wing parts, larger than the interval between outer faces (L4) of a pair of rock guards (L3 L4), the rubber crawler is made installable on equipment having a structure with a crawler runoff prevention guide or a rock guard. Since such rock guards are generally -11installed on the outermost side of the vehicle body frame, the above linkage type rubber crawler is made installable by the above structure on the undercarriage of all types of construction machines.

Also by making both outer sides of the rubber crawler body continuous in the circumferential direction and by making the width (Ll) of the wing part of the metallic Kcore, embedded in the rubber crawler body, shorter than the width (L2) of both outer ends of the central part of the metallic core (Ll L2), the cracking of the rubber is prevented by the dispersion of the load applied to the edges at both ends of the central part of the metallic body. Also by making the width (L2) of both outer ends of .the central part of the metallic core long, the thickness of the metallic core can be made thin while making the lug thickness thick to improve the durability of the lug.

o Furthermore, with the metallic core in which the central part is indented relative to the wing parts, the center of gravity of the equipment body can be set to a low position to improve travelling stability and secure an adequately high lug height and the part between the metallic cores, which is stretched when looped around the sprocket, etc., is improved in terms of durability since -12the reinforcing layer is provided with good flexibility and fatigue is prevented from accumulating at such a part.

The third invention of the present application presents a linkage type rubber crawler in which the metallic cores, comprised of left and right wing parts and a central part, are embedded at a fixed interval in a manner whereby the longitudinal direction of the metallic cores will be perpendicular to the circumferential direction of the rubber crawler body, lugs are provided at the ground side of the rubber crawler body, and a pair of track links is attached to the upper face of the central part of the metallic core, and front and rear track links are linked o o a mutually bendable manner to form a track comprised of a pair of continuous track links, said linkage type rubber crawler being characterized in that between adjacent metallic cores, the rubber crawler body is formed into a curved part, which curves towards the inner circumferential side, at the part between the wing parts S. and is stretched out at the part between the central parts to form a link protecting membrane.

W L iL iviLoi~ nce a link protecting membrane is formed between the central parts of the metallic cores, the entry of pebbles, mud, wood chips, -13etc. into the inner circumferential face of the rubber crawler during travel is prevented to reduce the chances of damaging the link or the engagement of the link pin with the sprocket and the external appearance is also improved since the interval between the central parts of the metallic cores is prevented from opening up widely when it loops around the sprocket, etc.

Li th s'cod and third "n'v¢ntiona bribe-abovc, tho o./ window space M, which is formed at the curved part where the rubber crawler body between adjacent metallic core wing parts is curved towards the inner circumferential side, may be provided with a thin rubber scale which partitions the window space M vertically into two parts.

By the scale passing across the window part, obstacles are prevented from entering into the inner circumferential face of the rubber crawler and since the curved part will 1 not lose flexibility, the concentration of rubber fatigue is prevented and the formation of cracks is restricted.

The fourth invention of the esents a linkage type rubber- crawler in which the metallic coSre rised of left and right wing parts and a central part, are embe a substantially fixed interval in a manner whereby the longitudinal dei on of -14- By embedding a connecting piece, that protrudes from the ront and rear of the rubber crawler shoe, in the rubber rawler shoe with a circumferential direction length corr ponding to one link, the same actions as those described ove can be obtained and since the number of links can be anged in link units, the general applicability to equipme with different number of links is improved.

Also, the -abovementioned ru er crawler shoe is convenient to carry and easy to ha e since it is lightweight and is economical since replace nts can be p ,rformod in !ink.nts.

BRIEF DESCRIPTION OF THE DRAWINGS .I Figs.l-7 show a preferred embodiment of the first invention. Fig.l is a perspective view of the linkage type rubber crawler. Fig.2 is an overall side view of a travelling equipment onto which the linkage rubber crawler has been installed. Fig.3 is a cross section in the width S direction along line A-A of Fig.2. Fig.4 is a partially enlarged view of Fig.2. Fig.5 is a diagram which explains .Ode.. the actions of the bellows part (curved part). Fig.6 shows another preferred embodiment of the first invention and is a cross section in the width direction of the same part shown in Fig.3. Fig.7 shows another preferred embodiment of the first invention and is a partially enlarged view of the same part shown in Fig.4.

Fig.8 shows one preferred embodiment of the invention disclosed in a prior laid-open Japanese patent publication No. Hei-4-71386 by the present inventor, with Fig.8A being a plan view (ground side) and Figs.8B and C being cross Ssections along lines B-B and C-C of Fig.8A, respectively.

Fig.9 is a diagram which explains the condition in which the linkage type rubber crawler is looped around the driving wheel and the idler wheel.

S.

Fig.10 shows a travelling equipment onto which a prior art linkage type rubber crawler has been installed, with Fig.l1A being a side view and Fig.lOB being a cross S 15 section along line Z-Z of Fig.lOA.

Fig.ll shows the semi-endless crawler disclosed in Japanese patent application No.Hei-6-94043, with Fig.llA being a perspective view and Fig.llB being a cross section in the circumferential direction of the connection part.

20 Figs.12-18 show the second and third inventions. Fig.12 shows a metallic core embedded in a linkage type rubber crawler, with Fig.12A being a plan view, Fig.12B being a cross section along line A-A of Fig.12A, and Fig.12C being -16a cross section along line B-B of Fig.12A. Fig.13 shows the linkage type rubber crawler, with Fig.13A being a ground side plan view and Fig.13B being a plan view of the inner circumferential side. Fig.14 shows cross sections of Fig.13, with Fig.14A being the cross section along line C- C, Fig.14B being the cross section along line D-D, and Fig.14C being the cross section along line E-E. shows the usage condition of the linkage type rubber crawler. Fig.16 shows another linkage type rubber crawler, with Fig.16A being a perspective view of the metallic core and Fig.16B being a diagram showing the usage condition of a linkage type rubber crawler into which said metallic core is embedded. Fig.17 shows the usage condition of a linkage type rubber crawler into which another metallic 15 core is embedded.

Fig.18 shows the rubber crawler shoe of another invention, with Fig.18A being a perspective view and Fig.18B being a partly broken away side view which shows the linkage condition.

197'.19-5 conc r preferred nibUnenS- e fourth invention. Fig.19 i erspective view of a linkage type rubber crawler. Fig.20 is a c section in the 'ir..c u .ferenti' c ich shows the conn n part -17- "--bthelirnKage type rubber Clwl. is p rspective view of the connecting piece. Fig.22 is a side vie showing the engagement condition of another preferred embo iment -of the connecting piece. Fig.23 is a cross sectio in the circumferential direction of the connected part o the linkage type rubber crawler of the second preferre embodiment. Fig.24 is a cross section in the circumfere tial direction of the connected part of the linkage ty e rubber crawler of the third preferred embodiment. Fig.25 is a cross section in the circumferentia direction of the connected part of the linkage type ubber crawler of the fourth preferred %bod1 BEST MODE FOR CARRYING OUT THE INVENTION 15 -PreefE-ed qbodiments of the .oB invention shall now be described with reference to the drawings. Fig.l is a perspective view of the linkage type rubber crawler by the invention. Fig.2 is an overall side view of a travelling equipment onto which said linkage rubber crawler has been installed. Fig.3 is a cross section in the width direction along line A-A of Fig.2. Fig.4 is a partially enlarged view of Fig.2.

-18- In the Figures, 1 is the rubber crawler body. The metallic cores 2, having wing parts 2a extending to the left and right, an indented central part 2b, and bolt holes 2p for attaching track link 6 by means of bolt 6p and nut 6n, are embedded at a fixed interval in this rubber crawler body i. 3a is a wing part lug, which protrudes towards the ground side of the rubber crawler at Sa position corresponding to the metallic core wing part 2a, and 3b is a central lug, which corresponds to the central part 2b of metallic core 2. A bolt hole 3b is formed on central lug 3b in correspondence to bolt hole 2p of metallic core 2.

4 is a bellows part made by shaping the rubber crawler .":body into a wave-like shape between embedded the metallic 15 cores 2. There are no protruding parts on the inner circumferential face of the rubber crawler body i r-r emndimej t rock guard11 is provided near p~~tfeLLd kmoi~j, rock 11unea idler wheel 9 to prevent pebbles, dirt, etc. from becoming caught. Since the tip of this rock guard 11 extends to the inner circumferential face of the rubber crawler body i, the inner circumferential face of rubber body 1 must have a flat surface and be prevented from contacting rock guard 11. As shown in Fig.5, the bellows part 4 has a length -19which enables it to be positioned at nearly the same height as link pin 7 and can therefore stretch adequately when it is looped around driving wheel 8 or idler wheel 9.

The accumulation of rubber fatigue by repeated stretching can thus be prevented.

is a reinforcing layer made by cutting a nylon cord fabric in the oblique (biased) direction with respect to 9 the weft and is embedded in the oblique (biased) direction below metallic core wing part 2a along the entire circumference of the rubber crawler body i. By embedding reinforcing layer 5 in a biased manner, reinforcing layer itself is provided with the ability to stretch, enabling the rubber crawler to be installed even if the length of the rubber crawler body 1 between the metallic cores 2 is 15 not as long as the interval between link pins 7.

Reinforcing layer 5 can be made of high-tension natural, synthetic, or carbon fiber, as well as fabrics of such fibers or metallic fiber cords and is embedded above or S. below or both above and below metallic core wing part 2a.

Figs.6 and 7 show another +Qe4@d embodiment of the *invention with Fig.6 showing the cross section of the same part shown in Fig.3 and Fig.7 being the side view of the e same part show in Fig.4. As shown in these Figures, *o o metallic core 12 is not formed so that its central part 12b is indented with respect to wing parts 12a, which extend to the left and right, but is formed in a flat shape. Adequate length to the position of link pin 7 can be secured even when such a metallic core 12 is used if the rubber crawler body 1 is made into a bellows part 4 between the metallic cores 12.

fi inuiibed ~e rubber crawler body has a bellows-like form between two embedded metallic cores in a linkage type rubber crawler in which a pair of continuous track links is formed at the center in the width direction on the inner circumferential side of the rubber crawler. The rubber crawler can thus be looped smoothly around the driving wheel and the idler wheel and 15 the lifetime of the rubber crawler can be extended since fatigue due to repeated stretching will not accumulate in the rubber material. Furthermore, by inserting a reinforcing layer in a biassed manner above or below or S. both above and below the metallic core wing part in a linkage type rubber crawler in which a pair of continuous track links is formed at the center in the width direction on the inner circumferential side of the rubber crawler, o the reinforcing layer itself is made stretchable. Since, -21the reinforcing layer is thus prevented from becoming stretched excessively and cut, the durability of the rubber crawler is improved.

e f embo ments of the se nd-ad t-rTd inventionj shall now be described with reference to the drawings. Figs.12A-C show a metallic core embedded in a linkage type rubber crawler by the invention. Fig.12A is plan view of the metallic core, Fig.12B is cross section along line A-A of Fig.12A, and Fig.l2C is a cross section along line B-B of Fig.12A. Metallic core 201 is comprised of wing parts 201a, which extend to the left and right, and a central part which is indented relative to wing parts 201b. Bolt holes 201p, for the attachment of track links 205 (see Fig.15), are bored in central part 201b. An 15 area of central part 201b, with a length of approximately 1/2 or less the length from bolt holes 201p to the wing part 201a side, is provided with a width L2, which is greater than width L1 of wing part 201b, as a central end S* part 201c. The inner circumferential face of central end part 201c is formed into a concave surface which will not contact the rock guard to be described later. R in the Figures indicates a rib.

o -22- Figs.13 and 14 show a linkage type rubber crawler into which the abovementioned metallic core 201 has been embedded. Figs.13A and B are plan views respectively of the ground- side and the inner circumferential side and Figs.14A-C are cross sections along lines C-C, D-D, and E- E of Fig.13A, respectively. The metallic cores 201 are embedded inside the rubber crawler body 202 at a fixed interval and with the inner circumferential face of central part 201b of metallic core 201 being exposed. On the ground side of the rubber crawler body 202, wing part lugs 203a are protruded at both ends in the metallic core length direction and a central lug 203b, with bolt holes 202p bored therein, is protruded at the center in the width direction. Although wing part lug 203a has a shape 15 which nearly covers the wing part 201a and central end part 201c of metallic core 201, the lug parts 203c, corresponding to central end parts 201c, comprise areas on which the weight of the equipment body tend to be applied and at which the rubber crawler body 202 between the metallic cores 201 is discontinuous in the circumferential direction and does not have a reinforcing layer embedded therein. Since the load will thus tend to concentrate on lug parts 203c and since the lug thickness at these parts o *o -23will tend to be thinner than the parts of lugs 203a corresponding to the wing parts, the durability of lug parts 203c will tend to be poor. The width L2 of central end part 201c of metallic core 201 is thus made large to disperse the load applied to the edge of metallic core 201 to thereby prevent the cracking of the rubber.

Furthermore, by making L2 large and making the inner circumferential face a concave surface, the thickness of metallic core 201 can be made thin and the lug thickness can be made thick to thereby improve the durability of lug part 203c. The durability of the lug is improved further by inclining the corners of lug parts 203c, which tend to receive force during travel and rotation, by an angle of approximately 300-600 to thus provide a tapered part 203t.

15 Also, the rubber crawler body 202 is made continuous in the circumferential direction at both ends in the width "b direction and is curved towards the inner circumferential side between wing parts 201a of the metallic cores 201 to form a curved part 202. Furthermore, the rubber crawler body 202 is made discontinuous between central parts 201b of the metallic cores 201 and a link protecting membrane 204 is formed at such parts. Since a link protecting m 2e membrane 204 is provided at areas which were priorly 9 9o o*oo -24holes, the entry of mud and obstacles into the inner circumferential face is prevented to thereby prevent the damaging of the track link. Also, since link protecting membrane 204a is inclined towards the inner circumference, it takes on a shape that lines the link when the rubber crawler is looped around the sprocket, etc. Since this part therefore will not open up largely, the external appearance is also made favorable. In the Figures, 204b is a thin rubber scale, which divides the window- space M, formed at the border between curved part 202a and link protecting membrane 204a, into two parts in the vertical direction. As with link protecting membrane 204a, this rubber scale 204b prevents the entry of pebbles, wood chips, mud etc. into the track link side. This rubber 15 scale 204b also alleviates the concentration of cracks due to stretch fatigue at curved part 202a. Furthermore, a r e cord, such as a steel cord, synthetic fiber, natural fiber, etc. or a fabric made from such a cord a nylon cord fabric) is embedded as reinforcing layer s

S

below wing part 202a in a continuous manner in the C circumferential direction.

shows the usage condition of the linkage type rubber crawler of the invention installed on a travelling equipment, as seen from the direction of the width of the crawler. A pair of track links 205 is fixed by bolts to bolt holes 201p of the metallic core central part 201b and adjacent track links 205 are linked in a mutually bendable manner with link pin 206 to make the upper face of track links 205 a continuous travelling surface for rolling. 207 are rock guards which extend to both outer sides of track links 205 and these are attached near the idler of the vehicle body frame.- The tip of rock guard 207 extends close to the inner circumferential face of the rubber crawler body 202. Thus, with the invention, the rubber crawler body 202 is formed into a curved part 202a, with a height close to that of link pin 206, at both sides outside rock guards 207 and the length L3 of metallic core 15 central part 201b is set so that smooth looping is enabled without the tip of rock guard 207 coming into contact with rubber crawler 202 as shown in Figs.16A and B show another linkage type rubber crawler, with Fig.16A being a perspective view of the 20 metallic core and Fig.16B showing the usage condition of the linkage type rubber controller into which said *.-:metallic core is embedded. The metallic core of this preferred embodiment has the shape of a flat plate and is -26comprised of wing parts 208a, which extend to the left and right, and a central part 208b, with bolt holes 208p bored therein. The width L2 of both ends of central part 208b is made longer than the width L1 of the wing part 208a. As shown in the Figure, a curved part 202a, with a height close to the height of link pin 206, is formed at both sides outside rock guards 207. Also the rubber crawler body 202 is made continuous in the circumferential direction at both sides, including curved parts 202a, outside rock guards 207 while metallic core central part 208b is made discontinuous. The length of the central part 208b between the bolt holes 208p may be equal to width L1 of the wing parts 208a.

Fig.17 shows the usage condition of a linkage type 15 rubber crawler with yet another type of metallic core. In this preferred embodiment, the metallic cores 209, which are comprised of wing parts 209a, that extend to the left and right, step parts 209b', which are lowered with respect to the wing parts 209a so as not to contact rock 20 guards 207, and a central part 209b, which is lowered eeoc further to the height at which track links 205 are to be attached, are embedded in the rubber crawler body 202 at a fixed interval. By making step part 209b' higher than the -27central part 209 by one step, it becomes possible to make the lug height at the step part 209b' higher to thereby improve the durability of the lug. Here, the length direction dimension L3 of the central part is made greater than the interval between L4 of a pair of opposing rock guards.

Fig.18 shows divided--type rubber crawlers into which the metallic core of Fig.12 has been embedded. Fig.18A is a perspective view and FIg.l8B is a partly broken away side view of the condition in which the divided type rubber crawlers have been linked. The divided type rubber crawlers have a circumferential direction length corresponding to one link of track link 205. Since these rubber crawlers are mutually separated, the linked part 15 210 opens up when the crawlers are looped around a sprocket, etc. and tend to cause foreign objects to become 1 caught in linked part 210. The front and rear ends 211a and 211b in the circumferential direction are thus provided with a shape that is close to the shape of the 20 link pin 206 position to prevent the opening up of linked part 210. The indented metallic core 201, having a central part 201b with a length direction dimension L3 that is larger than interval between outer faces L4 of a pair of -28rock guards 207, is embedded in divided type rubber crawler body 211, lugs are made on the outer circumferential side, and bolt holes 211p are bored in the lugs in correspondence to the bolt holes formed on the central part 201b of metallic core 201 for attachment of track link 205. As shown in Fig.18B, a pair of track links 205 is fixed by bolts to the inner circumferential side of 'divided type rubber crawler 211 and the track links 205 of adjacent divided type rubber crawlers 211 are linked with link pins 206 to form an endless rubber crawler. S is a reinforcing layer that has been embedded to reinforce the divided type rubber crawler body 211. Although the circumferential direction length of the divided type rubber crawler was set equal to the length of one link in 15 this preferred embodiment, this length may be set equal to the length of two or more links. Also, one or more such divided type rubber crawlers may be arranged for connection at the end of a belt-shaped rubber crawler.

The metallic core and linkage type rubber crawler of 20 the invention is not limited to the above preferred ••go embodiments. That is, the metallic core and track link may be joined by means other than bolting, such as welding, and a reinforcing layer, made of cord or fabric of natural -29fiber, synthetic fiber, or other types of fibers, may be embedded along the entire circumference above or below or both above and below the metallic core wing parts.

The following effects are obtained by the second and third inventions described above.

That is, by making the rubber controller body continuous in the circumferential direction at both sides U outside the rock guards by means of a linkage type rubber crawler that is made into a continuous rolling track by the linking of track links attached to the inner circumferential side and by making the width (Ll) of the metallic core wing parts, embedded in the continuous rubber crawler body, shorter than the width (L2) of both ends of the metallic core central part (Ll L2), the 15 strength of the crawler in the circumferential direction e• is made high, excellent durability is provided, runoff is -A prevented, vibration during travel is reduced, and the durability of the lug is improved to thus provide a linkage type rubber crawler that can be favorably 20 installed even on travelling equipment with a rock guard.

Also, by making the central part of the embedded :.:"metallic core of the linkage type rubber crawler indented with respect to the left and right wing parts, by making the width of the central part greater than the width of the rock guard, etc., and by making the width at both ends of the central part greater than the width of the wing part, the -center of gravity of the equipment body is lowered to provide good travelling stability, the crawler is made installable as suited not only on conventional general equipment but also on travelling equipment with a rock guard, etc., and the durability of the lug is improved. A linkage type rubber crawler is thus provided which is excellent in terms of economy and general applicability.

Furthermore, by-tt 1 tiLJ.=- since a link protecting member is formed by stretching out the rubber crawler body between adjacent metallic core central parts and since a window-shaped rubber member is formed at the border between the link protecting membrane and the curved part, the entry of obstacles into the inner circumferential side is prevented, and the durability of the crawler is improved. A linkage type rubber crawler is 20 thus provided which is also favorable in external o* appearance.

y, preferred!11 t-t f he invente.n

~S

-31- Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

a o *g e *d o* go -32-

Claims (9)

1. A metallic core embedded in a linkage type rubber crawler, in which a protruding lug is provided at the ground side, a pair of track links is attached to the center of the inner circumferential side, said metallic core comprising a central part and two wing parts on opposed sides of the central part, characterized in that an attachment means for attachment of each track link is formed at the central part, and the dimension (L3) of the central part in the extent between the two wing parts is made greater than the interval between outer faces (L4) of a pair of rock guards protruding from the body frame of a machine on which the linkage type crawler is installed.

2. A metallic core according to claim 1 wherein the central part is indented with respect to the wing parts.

3. A metallic core according to claim 1 or 2 wherein each attachment means :.:°°comprises a bolt hole in the central part and wherein the width (L1) of each 15 metallic core wing part, to be embedded in the linked rubber crawler body, is o: made shorter than the width (L2) of a portion of the metallic core central part between each wing part and the respective bolt hole adjacent thereto. S 4. A metallic core according to claim 1, 2 or 3 wherein the pair of track links comprises first and second track links, wherein each of said first and second track links is adapted to be linked in a mutually bendable manner to ~corresponding first and second track links of similar metallic cores to form a track.

5. A metallic core according to claim 4 wherein respective track links are adapted to be linked in a mutually bendable manner by being pivotally connected together.

6. A linkage type rubber crawler having a metallic core according to any one of claims 1 to -33-

7. A linkage type rubber crawler comprising a rubber crawler body and a plurality of metallic cores embedded therein, the metallic cores each being in accordance with any one of claims 1 to

8. A linkage type rubber crawler according to claim 7 characterized in that the rubber crawler body is formed into a curved part which curves towards the inner circumferential side, at parts between the wing parts and is stretched out at the central part to form a link protecting membrane.

9. A linkage type rubber crawler according to claim 6 or 7 wherein a window space M, which is formed when the rubber crawler body between adjacent metallic core wing parts is curved, is provided with a thin rubber scale which partitions the window space M vertically into two parts. metallic core substantially as herein described with reference to the accompanying drawings.

11.A linkage type rubber crawler substantially as herein described with reference 15 to the accompanying drawings. ,Dated this fifth day of May 2000 FUKUYAMA RUBBER IND. CO. LTD Applicant Wray Associates Perth, Western Australia Patent Attorneys for the Applicant -34-