A CRAWLER PAD FOR THE TREAD BOARD OF A CRAWLER TRACK SHOE

Abstract: A crawler pad to be mounted on the tread board of a crawler track shoe comprises an elastic pad body (1) and a core metal (2) buried in the elastic pad body (1). The core metal (2) includes a locking member (4) movably inlaid therein, a fixed hook (6) rigidly secured to its one end, and a detachable hook (5) detachably secured to its other end. The locking member (4) and the detachable hook (5) have rack teeth on their mutual surfaces which are inclined to permit the detachable hook (5) to slide in its inserting direction and intermesh one another in its withdrawing direction, thereby allowing the detachable hook (5) to be locked. The detachable hook (5) has preferably a groove for inserting a releasing pin on its surface where the rack teeth are formed. The releasing pin is operable to unlock intermeshing between the rack teeth of the locking member (4) and the detachable hook (5).

Description: A CRAWLER PAD FOR THE TREAD BOARD OF A CRAWLER TRACK SHOE BACKGROUND OF THE INVENTION Field of the invention This invention relates to generally a crawler pad for the tread board of a crawler track shoe. More specifically, this ' invention concerns a crawler pad for protecting a road surface from- the endless track of a vehicle which carries various machinery for construction, civil and agricultural engineering etc. Description of the prior art It has been known that a crawler pad is fitted to the tread board of a crawler track shoe to protect the surface of road from the endless track of a vehicle on which such a machine for construction is mounted. The old crawler pad, on which serious abrasion has occurred due to heavy weight of vehicles and severe onsite operating condition, is needed to replace with new one. Recently, there have been some proposals to make it easy to replace an old crawler pad with new one. As a typical example, a crawler pad includes a core metal; a fixed hook rigidly secured to one end of the core metal and a detachable hook detachably secured to the other end of the same. It is necessary that the detachable hook can be easily secured to and detached from the core metal, whenever it is needed. As conventional means for detachably securing a detachable hook to a core metal, Japanese unexamined patent publication No.34085/93 and No.191447/94 disclose that a detachable hook is screwed to a core metal by means of a bolt. Further, it is known to use a lock pin (Japanese unexamined patent publication No.58647/96) or a slice lock (Japanese unexamir.ee patent publication No .119642/98 ) in stead of the bolt. However, these securing means such as a bolt, a lock pin and a slide lock is likely to come loose and off due to violent vibration of long duration. Also, in the prior art, as an attempt to improve the problem as set forth above, Japanese unexamined patent publication No.301233/97 has been known. In this invention, a metallic socket includes a hook part for holding a tread board and an inserting part for a rubber pad. The socket is applied to fasten them in such a manner that after inserting the inserting part into the slot of the rubber pad, a bolt is screwed into the holes of the inserting part and the tread board. But, in case where the bolt is embedded in the rubber pad, it is very difficult to come off the bolt, when the rubber pad is replaced. There are more complicated means for assembling the rubber pad and the tread board in place as disclosed in Japanese unexamined patent publication No.136678/97 , No.80984/93 and No. 7091/94. They could not be available in practical use due to expensive. Object of the invention An object of the invention is to provide a simple crawler pad that overcomes the drawbacks as set forth above and enable one to easily replace the old crawler pads with new ones by means of a device that permits a detachable hook to be firmly secured to and readily detached from a core metal. SUMMARY OF THE INVENTION In order to accomplish the above-mentioned and other objects, a crawler pad for the tread board of a crawler track shoe according to this invention comprises a pad body made of elastic material, a core metal buried in the pad body and is provided with a locking member having rack teeth consisting of at least one row of a tooth on its one surface, a fixed hook of which one end is rigidly secured to one end portion of the core metal and the other end is adapted to hold the tread board, a detachable hook of which one end surface facing the locking member has rack teeth consisting of at least one row of a tooth to intermesh with the rack teeth of the locking member and the other end is adapted to hold the tread board, the rack teeth on the locking member and the detachable hook being inclined to permit the detachable hook ' to slide in its inserting direction and intermesh one another in its withdrav/ing direction, thereby allowing the crawler pad on the tread board to be easily replaced when it is requested. The locking member preferably has engaging margins protruded from its opposite side edges. It is loosely fitted in an opening of one end portion of the core metal, so as to move upwardly and downwardly to the extent that the engaging margins of the locking member are engaged with the corresponding side edges of the opening. Alternatively, the locking member can be loosely fitted in the opening of a holding plate fixed to the one end portion of the core metal. It is desirable that the rack teeth on the locking member and the detachable hook comprise plural rows of a tooth respectively. Further, the detachable hook has a groove for inserting a releasing pin on its surface where the rack teeth are formed. The releasing pin is operable to unlock intermeshing between the rack teeth of the locking member and the detachable hook. A resilient piece is preferably placed between one end face of the core metal and the corresponding face of the detachable hook to bias the detachable hook in its withdrawing direction. According to the another aspect of this invention, a crawler pad for the tread board of a crawler track shoe comprising a pad body made of elastic material, a core metal buried in the pad body, a holding plate fixed to the one end of the core metal, a locking member having rack teeth consisting of plural rows of a tooth on its one surface and engaging margins protruded from its opposite side edges, the locking member being loosely fitted in the opening of the holding plate so as to move upwardly and downwardly to the extent that the engaging margins of the locking member are engaged with the corresponding side edges of the opening, a fixed hook of which one end is rigidly secured to the other end portion of the core metal and the other end is adapted to hold the tread board, a detachable hook of which one end has rack teeth consisting of plural rows of a tooth on the surface thereof to intermesh with the rack teeth of the locking member and other end is adapted to hold the tread board, having a groove for inserting a releasing pin on its surface where the rack teeth is formed, the releasing pin being operable to unlock intermeshing between both rack teeth on the locking member and the detachable hook, a resilient ' piece between one outer end face of the core metal and the corresponding face of the detachable hook to bias the detachable hook in its withdrawing direction, the rack teeth on the locking member and the detachable hook being inclined to permit the detachable hook to slide in its inserting direction and to intermesh one another in its withdrawing direction, thereby allowing the crawler pad on the tread board to be easily replaced when it is requested. BRIEF DESCRIPTION OF THE DRAWINGS Fig- 1 is a sectional front view showing a preferred embodiment of the crawler pad according to this invention. Fig. 2 is an enlarged, fragmentary front view showing a rack teeth of the detachable hook. Fig. 3 is a sectional front view showing a preferred encaging mechanism of the detachable hook and the locking member . Fig. 4 is a top plane view of Fig. 3. Fig. 5 is an enlarged front view showing the locking member in Fig . 3. Fig. 6 is a top plane view of Fig. 5. Fig. 7 is a bottom view of Fig. 5. Fig. 8 is a front view showing the detachable hook in Fig. 3. Fig. 9 is a top plane view of Fig. 8. Fig. 10 is a bottom view of Fig. 8. Fig. 11 is a right hand side view of Fig. 8. Fig. 12 is a right hand, fragmentary side view showing the state of disengaging between the detachable hook and the locking member by means of a releasing pin. Fig. 13 is a partially sectional, fragmentary front views showing another engaging mechanism between the detachable hook and the locking member. DESCRIPTION OF THE PREFERRED EMBODIMENT This invention will be discussed in detailed in terms of the preferred embodiments with reference to the accompanying drawin . In Fig. 1, a pad body 1 made of elastic material such as rubber is molded under heat and pressure so that a core metal 2 is buried therein. On the one end portion of the core metal 2, a fixed hook 6 is rigidly secured by way of welding, while on the other end portion of the core metal 2, a detachable hook 5 is detachably secured via a locking member 4. It is desirable that a holding plate 3 having an opening 3a is fixed to the one end portion of the core metal 2 where the detachable hook 5 will be set. The locking member 4 has engaging margins 4b protruded from both opposite side edges thereof and is assembled with the core metal 2 via the holding plate 3. For instance, the locking member 4 is loosely fitted in the opening 3a of the holding plate 3 to permit the locking member 4 to move upwardly and downwardly to the extent that the engaging margins 4b are engaged with the corresponding side edges of the opening 3a. In this invention, the locking member 4 and the detachable hook 5 have rack teeth 4a and 5a respectively on their mutual surfaces. The rack teeth 4a and 5a, each consisting of at least one row of a tooth are inclined to permit the detachable hook 5 to slide in its inserting direction and intermesh with the locking member 4. The detachable hook 5 can be set into a slot of the pad body 1 by hammering. It is preferred that a resilient piece 7 made of rubber and the like is placed between the side end face of the core metal 2 and the detachable hook 6. The resilient piece 7 bias the detachable hook 6 in the direction as indicated by arrow A and make it sure to engage between the rack teeth 4a and 4a, after setting the detachable hook 5 in place. The free end of each hook 5 and 6 is bent up to hold a tread board 8. In Fig. 2 and Fig 3, the rack teeth 5a of the detachable hook 5 are inclined similarly to the rack teeth 4a of the lock member 4 to permit the detachable hook 5 to smoothly slide in the inserting direction as indicated by arrow B in Fig. 2 and lock in the withdrawing direction as indicated by arrow A in Fig. 1. For example, the inclined surfaces X of the rack teeth 5a in Fig. 2 make it easy to slide the detachable hook 5 in the inserting direction, while the inclined surfaces Y make it sure to lock the detachable hook 5 in the withdrawing direction. The angle θl between the inclined surface X and the horizontal line is preferably within the range of from 30 to 60 degrees, and is practically at 45 degrees. The angle θ2 between the inclined surface Y and the horizontal line is preferably within the range of from 80 to 90 degrees and is practically at 90 degrees. The rack teeth should be formed into upset V shape, but can be formed into rounded one. In order to obtain more firm engagement between the rack teeth 4a and 5a, recess Z can be disposed on each inclined surfaces Y of the rack teeth 5 as shown by Fig 2. In this case, It is needed to provide a protrusion (not shown in any figure) corresponding to the recess Z on the inclined surfaces of the rack teeth 4a. The rack teeth may consist of one row of a tooth, but preferably of plural rows of a tooth. In Fig. 3, Fig. 4 and Fig. 5, the core metal 2 having the fixed hook 6 on its one end portion is provided with the holding plate 3 on its other end portion. The holding plate 3 is bored to form an opening 3a that serves as a frame for inlaying the locking member . The locking member 4 has an engaging margin protruded from both side edges thereof and the rack teeth 4a on its underside surface. The rack teeth 4a consist of at least one row of a tooth, preferably plural rows of a tooth. The locking member 4, of which the upper side surface is bonded to the pad body 1 by adhesive agent, is loosely fitted in the opening 3a of the holding plate 3 so as to move upwardly and downwardly in reaction to the heavy load which the pad body 1 takes, in the extent that the engaging margins 4b of the locking member 4 is engaged with the corresponding side edges of the opening 3a of the holding plate 3. As shown in Fig. 1, Fig 8, Fig 9, Fig 10 and Fig 11, The detachable hook 5 to be engaged with the locking member 4 has rack teeth 5a on its upper side surface which faces to the rack teeth 4a of the locking member 4. The rack teeth 5a consist of at least one row of a tooth, preferably plural rows of a tooth same as the rack teeth 4a. In case where the rack teeth 4a and 5a consist of plural rows of a tooth, they have advantages of not only obtaining firm engagement, but also being engageable therebetween, even though there are somewhat irregularity in the length of the pad body 1, as long as the irregularity of the length are within the range of length of the rack teeth 5a. On the surface of the detachable hook 5 where the rack teeth 5b are formed, a groove 5b for inserting a releasing pin 9 like a nail is also formed. The releasing pin 9 is operable to disengage between the rack teeth 4a and 5b. As shown in Fig. 12, when the releasing pin 9 is hammered into the groove 5b, the locking member 4 set in the opening 3a of the holding plate 3 moves up from the position indicated by the dotted line to the solid line against the resilient force of the pad body 1. Thus the engagement between the rack teeth 4 -and 5a is disengaged to permit the detachable hook 5 to readily remove. Fig. 13 indicates another different engaging mechanism between the detachable hook 5 and the locking member 4 from one shown in Fig 3 and Fig 4. In this embodiment, rack teeth 4a is formed on the upper side surface of locking member 4. The locking member 4 is loosely fitted in an opining 2a bored directly in the end portion of the core metal 2. The locking plate 4 has engaging margins 4b protruded from both sides thereof which are engageable with the corresponding side edges of the opening 2a of the core metal 2. A detachable hook 5 includes rack teeth 5a and a groove 5b on its underside surface. Although the rack teeth 5a and the groove 5b can be formed on one of the side surface of the detachable hook in stead of the upper side surface or the underside surface, it is better that the rack teeth 5a and the groove 5b are formed on the upper side face or underside surface of the detachable hook 5 in terms of the sizes and the relative positions of the pad body 1 and the core metal 2. In case where the crawler pad is manufactured by using the core metal 2 indicated by Fig. 3 and Fig. 4, first of all the core metal 2 is formed into U shape in its cross section. Then a fixed hook is welded to its one end portion, and a holding plate 3 with opening 3a is welded to its other end portion. The upper side of the locking member 4 is coated with adhesive agent. The locking member 4 having the rack teeth 4a on its underside surface is loosely fitted in the opening 3a of the holding plate 3 such that the surface where the rack teeth 5a are formed faces downwards. In order to prevent the locking member 4 from dislodging and form a slot of the pad body 1 for inserting the detachable hook 5, a dummy board for the detachable hook 5, which has no rack teeth 5a, but similar in size to it, is attached to the underside face of the core metal 2. Finally, rubber is molded into the shape of the pad body 1 as illustrated in Fig 1 by means of a metallic mold under heat and pressure so as to contain the core metal assembly set forth above therein. After cooling, the dummy board is removed. As the dummy board is being removed, the slot for inserting the detachable hook 5 is formed in the pad body, but the locking member 4 comes off from the holding plate 3, because the locking member 4 is adhered to the pad body 1. The crawler pad of this invention having structure as set forth above can be surly mounted on and readily removed from the tread board of the endless track shoes of vehicles which are widely used in the field of the construction and the like as follows. The fixed hook 6 welded on the one end portion of the core metal 2 hooks the tread board 8, while the detachable hook 5 is hammered into the slot of the pad body 1 against the resilient force of both pad body 1 and resilient piece 7 so as to hook the tread board 8. Inserting the detachable hook 5, it pushes up the lock member 4, which is loosely fitted in the opening 3a of the holding plate 3 as shown in Fig. 2. When the detachable hook is set in place, both rack teeth 4a and 5a of the lock member 4 and the detachable hook 5 is intermeshed therebetween. At the same time, the lock member 4 is push down and drawn back in outward direction by co-operation of the pad body 1 and the resilient piece 7, intermeshing between both rack teeth 4a and 5a become more tightly. Thus the crawler pad can be surely mounted on the tread board 8 by the fixed hook 6 and the detachable hook 5. When a vehicle is driven, the pad body 1 will come in touch with the road surface and the load of the vehicle is exerted on the pad body 1. Accordingly, the pad body 1 is compressed downwards with the load of the vehicle. This, in turn, will cause the locking member 4 to move downwards and lock tightly the detachable hook 5. To remove the crawler pad, the releasing pin 9 can be hammered into the groove 5b of the detachable hook 5. The locking member 4, which is loosely set in an opening 3a of the holding plate 3, will be move up against the resilient force of the pad body 1 from the position indicated by dotted line to the solid line as shown in Fig. 12. Thus the intermeshed between both rack teeth 4a, and 5a is disengaged, and then the detachable hook 5 can be removed. After removing the detachable hook 5, the crawler pad with the fixed hook 6 can also removed from the tread body 8. The crawler pad of this invention can be suited for heavy-duty vehicles with endless track widely used in the field of construction, civil and agricultural engineering etc., and can protect road surface from the endless track of the vehicles. According to this invention, there are many other advantages as follows. (1) As means for locking detachable hook to the core metal, the rack teeth, instead of a bolt and a hook pin etc. is used in this invention. As a result, the firm locking is obtainable in simple operation. Particularly In case where the rack teeth consist of plural rows of a tooth, the locking will not only be enhanced, but the discrepancy in the length of the pad body can also be tolerated. (2) By allowing the lock member to move freely in the pad body, locking between the rack teeth of the lock member and the detachable hook will be reinforced, as the crawler pad comes in touch with the road surface and load is added to the lock member via the pad body. In addition, when the detachable hook is removed, the operation is very simple. Namely, when the release pin is hammered into the slot of the removable hook, the lock member moves up and then the locking of the rack teeth is disengaged quite simply. (3) The resilient piece is preferably placed between the end face of the core metal and the corresponding face of detachable hook acts to bias the detachable hook in withdrawing direction. After inserting the detachable hook in to the slot of the pad body against the resilient force of the resilient piece, the detachable hook set in place is drawn back in the outwards by the resilient force of the resilient piece, thereby making engaging of the two sets of the rack teeth even more securely.

Claims: CLAIMS : 1. A crawler pad for the tread board of a crawler track shoe comprising; a pad body made of elastic material, a core metal buried in the pad body and is provided with a locking member having rack teeth consisting of at least one row of a tooth on its one surface, a fixed hook of which one end is rigidly secured to one end portion of the core metal and the other end is adapted to hold the tread board, a detachable hook of which one end surface facing the locking member has rack teeth consisting of at least one row of a tooth to intermesh with the rack teeth of the locking member and the other end is adapted to hold the tread board, the rack teeth on the locking member and the detachable hook being inclined to permit the detachable hook to slide in its inserting direction and to intermesh one another in its withdrawing direction, thereby allowing the crawler pad on the tread board to be easily replaced when it is requested. 2. A crawler pad for the tread board of a crawler track shoe according to claim 1, wherein the locking member have engaging margins protruded from its opposite side edges and is loosely fitted in an opening disposed at one end portion of the core metal so as to move upwardly and downwardly to the extent that the engaging margins of the locking member are engaged with the corresponding side edges of the opening. 3. A crawler pad for the tread board of a crawler track shoe according to claim 1, wherein the locking member has engaging margins protruded from its opposite side edges and is loosely fitted in the opening of a holding plate fixed to the one end portion of the core metal so as to move upwardly and downwardly to the extent that the engaging margins of the locking member are engaged with the corresponding side edges of the opening. 4. A crawler pad for the tread board of a crawler track shoe according to claim 1, 2 or 3, wherein the rack teeth on the locking member and the detachable hook comprise plural rows of a tooth respectively. 5. A crawler pad for the tread board of a crawler track shoe according to claim 1, wherein the detachable hook has a groove for inserting a releasing pin on its surface where the rack teeth are formed, the releasing pin being operable to unlock intermeshing between both rack teeth of the locking member and the detachable hook. 6. A crawler pad for the tread board of a crawler track shoe according to claim 1, wherein an resilient piece is placed between one end face of the core metal and the corresponding face of the detachable hook to bias the detachable hook in its withdrawing direction. 7. A crawler pad for the tread board of a crawler track shoe comprising; a pad body made of elastic material, a core metal buried in the pad body, a holding plate fixed to the one end of the core metal, a locking member having rack teeth consisting of plural rows of a tooth on its one surface and engaging margins protruded from its opposite side edges, the locking member being loosely fitted in the opening of the holding plate so as to move upwardly and downwardly to the extent that the engaging margins of the locking member are engaged with the corresponding side edges of the opening, a fixed hook of which one end is rigidly secured to the other end portion of the core metal and the other end is adapted to hold the tread board, a detachable hook of which one end has rack teeth consisting of plural rows of a tooth on its surface to intermesh with the rack teeth of the locking member and other end is adapted to hold the tread board, having a groove for inserting a releasing pin on its surface where the rack teeth are formed, the releasing pin being operable to unlock intermeshing between both rack teeth on the locking member and the detachable hook. a resilient piece being placed between one outer end face of the core metal and the corresponding face of the detachable hook to bias the detachable hook in its withdrawing direction. the rack teeth on the locking member and the detachable hook being inclined to permit the .detachable hook to slide in its inserting direction and to intermesh one another in its withdrawing direction, thereby allowing the crawler pad on the tread board to be easily replaced when it is requested. '

Inventors: HATTORI TOMITARO, HATTORI, TOMITARO
Applicants: CHU THOAI QUANG, HATTORI TOMITARO, CHU, THOAI, QUANG, HATTORI, TOMITARO
Application year: 1999
Main classification: B62D55
IPC codes: B62D55