Wheel substitutes for land vehicles – With means to remove or exclude foreign matter – With end seal between bushing and track link
Reexamination Certificate
2000-07-14
2002-05-21
Morano, S. Joseph (Department: 3617)
Wheel substitutes for land vehicles
With means to remove or exclude foreign matter
With end seal between bushing and track link
C305S104000, C305S106000
Reexamination Certificate
active
06390572
ABSTRACT:
TECHNICAL FIELD
This invention relates to a crawler belt suitable for use on crawler type vehicles such as hydraulic excavators, hydraulic cranes and the like.
BACKGROUND ART
Generally, crawler type vehicles such as hydraulic excavators are equipped with crawler belts for running or traveling purposes. Crawler belts of this sort are usually constituted by; right and left track links each having outer and inner link portions along opposite longitudinal sides thereof; bushes located transversely between inner link portions of the respective track links, and having transversely opposite ends of the respective bushes located in confronting relation with the outer link portions of the track links; connecting pins inserted in the respective bushes and having transversely opposite ends fitted and securely fixed in the outer link portions; and seal devices provided between the bushes and the outer link portions of the respective track links (e.g., as disclosed in Japanese Laid-Open Utility Model Publication No. S48-27535 and S49-113342).
The prior art crawler belts of this sort are each passed around an idle wheel and a drive wheel, and, as the drive wheel is rotated by a hydraulic motor or the like, the crawler belts are turned around between the idle and drive wheels to move a vehicle body in a forward or reverse direction.
Further, in the case of the prior art crawler belts just mentioned, rubber seals such as urethane rubber seals on the like are fitted between the bushes and outer link portions of track links to prevent intrusion of dirt or soil into gaps between the bushes and connecting pins, and at the same time to prevent leakage of grease which lubricates these members.
On the other hand, as another example of the prior art, there have been known crawler belts of a construction employing steel coned disc spring in place of the above-mentioned rubber seals for sealing gaps between the bushes and outer link portions of track links (e.g., as disclosed in Japanese Utility Model Publication No. S50-23945).
In the case of this prior art construction, as the crawler belts are turned around, the coned disc spring are held in sliding contact with end faces of the track links and bushes, thereby applying suitable sliding resistance to adjoining track links to prevent the crawler belts from flapping up and down to a considerably large degree.
Further, in another prior art crawler belt construction, ring-like spacers are fitted on connecting pins at positions between track links and bushes, and the spacers are each provided with a lip seal around its outer periphery for sliding contact with an end face of a bush; in association with a load ring which is adapted to press the lip seal resiliently toward the bush (e.g., as disclosed in Japanese Laid-Open Patent Publication No. H2-93170).
In the case of the prior art construction just mentioned, the thrust load which acts between the bushes and the track links is supported by means of spacers to prevent the thrust load from directly acting on the lip seals, thereby enhancing durability of the lip seals.
By the way, according to the prior art just mentioned, the rubber seals are interposed in a compressed state between the bushes and outer link portions of the track links and resiliently held in sliding contact with end faces of the bushes.
In this regard, in order to further enhance the sealing functions of the rubber seals, an increased
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compressive load is applied to the rubber seals between the bushes and track links for the purpose of elevating the surface pressure of rubber seals which are in sliding contact with end faces of the bushes.
However, according to published prior art such as Japanese Laid-Open Utility Model Publication No. S48-827535, for example, if the compressive load on rubber seals is increased to an unnecessarily large degree, it will give rise to large sliding resistance between the rubber seals and bushes, causing abrasive wear to sealing surfaces of the rubber seals prematurely in an early stage and as a result deteriorating their sealing functions to a considerable degree.
Especially in case the compressive load is continuously applied to the resilient bodies of the rubber seals over a long period of time, plastic deformation (permanent deformation) could occur to the rubber seals due to fatigue. In such a case, the rubber seals are worn out between the bushes and gaps are opened depending upon the degree of wear to deteriorate their sealing functions.
Further, according to still another prior art construction as shown in Japanese Utility Model Publication No. S50-23945, seals of simple linear contact are formed by arranging coned disc springs in contact with outer link portions of the track links and end faces of the bushes. In this case, the contact areas of the coned disc springs and outer link portions are extremely small and insufficient to provide stable seals. In addition, coned disc springs are susceptible to corrosion or rust which would sooner or later lead to deteriorations in sealing functions.
Further, according to a prior art crawler belt construction as shown in Japanese Laid-Open Patent Publication No. H2-93170, load is applied to lip seals in a compressive direction by means of load rings of synthetic resin or similar resilient material. Naturally, the load rings of synthetic resin material as employed in this prior art are incapable of generating sufficient sliding resistance between the lip seals and bushes, thereby permitting the crawler belts to flap up and down easily during traveling operations to impair the performance quality of the machine in travel.
Furthermore, recently, it often become necessary for the crawler type vehicles of this sort to be moved from a remote working site to a nearby storage station or place which is located within a manageable distance. In such a case, since a transfer of a crawler type vehicle on a truck involves impractically troublesome steps, it has been the general practice to move a crawler type vehicle by itself for a travel to or from a working or storage place. Consequently, the crawler type vehicle is forced to travel over an unduly long distance, and, due to the large sliding resistance acting on the seals which are interposed between track links and bushes, the seals of the above-described prior art constructions lose sealing functions prematurely within a shortened period of time, thereby suffering from a short service life.
DISCLOSURE OF THE INVENTION
In view of the above-mentioned problems with the prior art, it is an object of the present invention to provide a crawler belt which uses seal rings in combination with coned disc springs in such a way as to enhance durability of the seal rings against loads acting in compressive directions, thereby ensuring a stable sealing capacity over a long period of time.
In order to achieve the objective just mentioned, according to the present invention, there is provided a crawler belt which includes right and left track links each consisting of a large number of track links successively connected in an endless form, each one of the track links being provided with an outer link portion at one longitudinal end and an inner link portion at the other longitudinal end thereof; bushes each located transversely between the inner link portions of the right and left track links to have opposite ends thereof in face to face relation with outer link portions of the truck links; connecting pins inserted in the bushes and having opposite ends thereof fitted in and connected to the outer link portions of the track links; and a sealing device located around a connecting pin in a gap spaces between an outer link portion of the track links and an opposing one of the bushes.
The crawler belt construction according to the present invention is characterized in that the sealing devices are each constituted by a seal ring formed of a resilient material in a ring-like shape having a diameter larger than that of the connecting pin and set in position to form a seal between the outer link portion and an opposing end face of the bu
Hatano Kazuyoshi
Idetsu Wataru
Sekiguchi Yoshiaki
Sugiyama Genroku
Bellinger Jason R.
Hitachi Construction Machinery Co. Ltd.
Mattingly Stanger & Malur, P.C.
Morano S. Joseph
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