Track-type machines are in widespread use in construction, mining, forestry, and other similar industries. The undercarriage of such track-type machines utilizes track assemblies, rather than wheels, to provide ground-engaging propulsion. Such track assemblies may be preferred in environments where creating sufficient traction is problematic, such as the environments identified above. Specifically, rather than rolling across a work surface on wheels, track-type machines utilize one or more track assemblies that include an endless loop of coupled track links defining exterior surfaces, which support ground-engaging track shoes, and interior surfaces that travel about one or more rotatable track-engaging elements, such as, drive sprockets, idlers, tensioners, and rollers, for example.
Typical track chain assembly designs include a track pin either rotatably or fixed to a pair of chain links and a bushing rotatably positioned between the links and about the track pin. Such track chain assemblies can operate in extremely adverse environments in which track joints may be exposed to various abrasive mixtures of water, dirt, sand, rock or other mineral or chemical elements.
Consequently, seal assemblies are placed in the track joints to exclude contaminants and retain lubricant within the track joint to facilitate the aforementioned relative movement of the bushings and the track links during use. A common type of seal used in track chains is referred to as a “can” seal. A can seal often includes a “lip” supported by a can and a load ring engaging the can.
These designs have included a variety of seal configurations and positions such as against an inside face of the link or against the track bushing. For example, U.S. Pat. No. 6,739,680 for a “Cartridge Assembly for a Track Chain,” issued May 25, 2004, to Hasselbusch et al. is directed to a cartridge assembly for a track chain assembly which includes a bushing rotatably positioned about a track pin. Bearing members are positioned about the track pin adjacent the bushing. Collars are positioned about the track pin adjacent the bearing members. Seal arrangements are positioned between the collars and the bearing members and between the bearing members and the track bushing sealably excluding contaminants and the retention of a lubricating fluid from a passage in the bushing and a bore within the track pin.
One cause of failure of current seals is known in the art as “heel under.” Heel under describes the situation where debris is ingested between an outer surface of a load ring of the seal assembly and the seal cavity within which the seal assembly is housed. The debris builds up and can cause the load ring to rotate or move out of position against a seal ring resulting in the failure of the seal and leakage of lubricant.
It will be appreciated that this background description has been created by the inventors to aid the reader, and is not to be taken as an indication that any of the indicated problems were themselves appreciated in the art. While the described principles can, in some respects and embodiments, alleviate the problems inherent in other systems, it will be appreciated that the scope of the protected innovation is defined by the attached claims, and not by the ability of any disclosed feature to solve any specific problem noted herein.