Land vehicles: wheels and axles – Wheel – Hub
Reexamination Certificate
2000-07-07
2001-09-25
Morano, S. Joseph (Department: 3617)
Land vehicles: wheels and axles
Wheel
Hub
Reexamination Certificate
active
06293631
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to improvements for land vehicles such as off road equipment and, in particular, to guards for the drive of wheels or sprockets for the same.
U.S. Pat. No. 5,713,644 illustrates a cutter device to reduce wear and tear on the final drive of a crawler such as manufactured Caterpillar, Inc. This cutter device is especially useful on machines operating on landfills that accept residential and commercial refuse, for example. Landfill environments present severe service conditions on machinery due to the mix of debris typically found at such sites. Material over which a machine runs tends to be drawn up and around rotary parts eventually leading to excessive wear through abrasion and oftentimes to catastrophic failure because of destruction of seals between parts rotating relative to one another. A need exists for a device that can protect drive areas of equipment of the type described in landfills, construction sites and other off road situations where the environment is adverse and that provides an alternative to the cutter device disclosed in the aforementioned patent for situations that are less than extreme.
More specifically, rotating drive wheels in the form of track chain sprockets, for instance, rotate relative to their support housings and normally have associated seals to protect bearings and gears within the housings that support the sprocket hubs for rotation. The housings are subject to high wear rates through abrasion by debris entwined on the rotating parts. This debris eventually can wear through the walls of the housing causing catastrophic failure of bearings and related parts.
Where a seal on a final drive of a crawler is damaged prematurely by intrusion of debris, the cost to repair the same may range, by way of example, between $3,000 to $4,000. Wear on a final drive housing or sprocket hub can cost as much as $7,000 to $8,000 in repair. A loss of oil from a damaged seal can result in repair work for internal damage of as much as $50,000.
It is desirable, especially for large machines where the major drive components are too heavy to be manipulated by hand, that any protective guard be capable of being installed without dismantling and reinstalling such major components of the machine.
SUMMARY OF THE INVENTION
The invention provides a guard for drive assemblies of commercial land vehicles such as track mounted machines sometimes referred to as crawlers. Chain sprockets for the track are rotatably supported on housings at opposite sides of a crawler. In the disclosed embodiment, the guard extends between a fixed housing on the main body or frame of the machine and the hub supporting a track chain sprocket. The guard preferably has a relatively large diameter so it occupies most of the space available adjacent the path of the track chain. This geometry advantageously limits the amount of debris that can accumulate on the sprocket adjacent the rotating areas.
An important aspect of the invention is the ability of the guard to be installed on a machine without requiring disassembly and reassembly of major parts of the final drive system. The disclosed guard shares the original mounting bolt locations of the drive system but is configured to allow at least some of the mounting bolts to remain in place at locations circumferentially spaced around the axis of rotation of the sprocket while the guard is being installed. This feature ensures that various drive line parts will be safely held in place without being stressed in a manner that could cause physical damage or even bodily injury.
Another important feature of the invention is the provision of telescoping parts that enable the entire gap between the housing and sprocket to be protected from entry of debris. The telescoping guard portions in the illustrated embodiment have a labyrinth-like configuration which reduces the risk that debris could work its way into the guard.
The disclosed guard has demonstrated remarkable effectiveness in protecting the seals of the sprocket drive while achieving excellent durability. All of the reasons for the performance of the guard are not yet fully understood, but it is believed that major factors are related to the relatively large diameter of the guard in comparison to the diameter of the sprocket. First, since the circumference of the guard is relatively long, the risk that a strand of cable, rope, wire, strapping, fabric or the like will be long enough to wrap numerous times around the guard is reduced. Second, the close proximity of the guard to the underside surfaces of the track apparently allows the system to be self-cleaning such that the track “scrubs”, in a non-contact manner, the external surface of the guard. The smooth character of the circular guard in the circumferential direction, additionally, appears to play a role in the anti-wrapping and durability performance.
REFERENCES:
patent: 1812543 (1931-06-01), White
patent: 2146882 (1939-02-01), Baker et al.
patent: 3861762 (1975-01-01), Freedy et al.
patent: 3912336 (1975-10-01), Ritter Jr. et al.
patent: 5676493 (1997-10-01), Brockway
patent: 5713644 (1998-02-01), Freeman
patent: 5733020 (1998-03-01), McCartney et al.
patent: 5820230 (1998-10-01), Freeman
patent: 5951123 (1999-09-01), Bomstad et al.
patent: 6019443 (2000-02-01), Freeman
Morano S. Joseph
Nguyen Long Bao
Pearne & Gordon LLP
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