Earthmoving equipment is used to perform a variety of operations, including loading, or capturing, material, such as soil, at one location and dumping, or depositing, the material at another location. For example, such material movement may be employed to adjust elevations at a project site. Scrapers, which typically provide quick load, dump, and maneuver time, may be used to perform such operations, and generally include a machine having a bowl within which material may be captured, and a cutting edge located adjacent a cut opening of the bowl. Although various scraper configurations are available, scrapers are often pulled by a tractor, such as a wheeled or track type tractor. In addition, scrapers may provide their own traction via a separate engine that applies rim pull, or power, to the wheels of the scraper. In either arrangement, scrapers may also be pushed and/or pulled by a separate machine, or tractor, to provide additional power for scraper operations.
For example, during a typical push-pull operation, a first scraper may move into a loading area and take a shallow cut as a second scraper moves in behind to push the first scraper as it loads. When approaching the first scraper, the second scraper may align a push plate, positioned at the front of the second scraper, with a push block, positioned at the back of the first scraper. Once the first scraper is loaded, it may serve as a tow unit for the second scraper. Specifically, a movable bail, or tow bar, also positioned at the front of the second scraper, may engage a corresponding hook positioned at the back of the first scraper, effectively connecting or coupling the two scrapers together. Once the second scraper is loaded, the two scrapers may disconnect and travel to a fill location, or other suitable unloading site. Such a push-pull operation, as should be appreciated, may allow scrapers to load more quickly, thus improving production and lowering costs.
Typically, the push-pull coupling, or hitch assembly, provided at the front of the second scraper, as described above, includes a bail, or tow bar, and a push plate. For example, as shown in U.S. Pat. No. 4,088,341, the front of a scraper may include a push plate, which is pivotably connected to a frame. A U-shaped bail, or drawbar, includes two free ends that are pivotably attached to the frame at either side of the push plate. As further taught in the cited reference, the U-shaped bail and push plate may utilize a common shock absorber to cushion impact during both push and pull operations. Although this push-pull coupling may facilitate typical push-pull operations, it should be appreciated that there is a continuing need for push-pull couplings, or hitch assemblies, including tow bars and push plates, which facilitate improved push-pull operations, while reducing damage that may occur to the tow bar, push plate, or machine.
The present disclosure is directed to one or more of the problems set forth above.
USPTO Backgrounds
USPTO Backgrounds