Material or article handling – Self-loading or unloading vehicles – Conveyor
Reexamination Certificate
1998-09-25
2001-01-23
Bratlie, Steven A. (Department: 3652)
Material or article handling
Self-loading or unloading vehicles
Conveyor
C296S057100, C298S0230MD, C414S519000
Reexamination Certificate
active
06176673
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to a tailgate assembly, and more specifically to a tailgate assembly having side mounted hydraulic cylinders.
BACKGROUND OF THE INVENTION
Work machines are used in earth moving operations to move material, such as dirt and rock, from one point to another. Conventional dump type work machines dump material by elevating a receptacle of the work machine with hydraulic cylinders. The force of gravity causes the material to be dumped out of the rear of the receptacle. There are several disadvantages to this type of work machine. First, elevating the receptacle of the work machine raises the center of gravity of the work machine making it less stable. Second, the raised receptacle can easily come into contact with overhead obstacles such as power lines or trees, which can limit the maneuverability of the work machine. Third, once the material begins to move in the receptacle, the material exits the receptacle quite rapidly, making it difficult for an operator of the work machine to spread the material evenly over a large area. In fact, a bulldozer is often employed to evenly distribute the material after it has been dumped from the work machine. Fourth, material, particularly dirt containing clay, can often stick to the receptacle of the work machine as the receptacle is elevated. The material stuck to the receptacle decreases the amount of material that can be moved by the work machine. In addition, an excavator or backhoe must be used to scrape the material from the receptacle, which can potentially damage the receptacle.
An ejector type work machine is an alternative to the conventional dump type work machine. Ejector type work machines do not elevate the receptacle to unload material. Instead, a hydraulic cylinder, or cylinders, urges an ejector plate between the front and the rear of the receptacle. As the ejector plate moves from the front to the rear of the receptacle, material is ejected out of the receptacle at a controlled rate. Because the receptacle is not raised, the center of gravity is not increased as the material is ejected. Therefore, the stability of the ejector type work machine is not decreased as the material is ejected. In addition, the receptacle is not raised so as to be exposed to overhead obstacles such as trees and power lines. Moreover, the rate that the material is ejected from the rear of the ejector type work machine can be controlled, making it possible to evenly distribute the material over a large area thereby reducing the need to employ a bulldozer to spread the material. Also, because the ejector plate tightly matches the shape of the receptacle, any material that sticks to the receptacle is scraped out of the receptacle during the ejection process thereby increasing the amount of dirt that can subsequently be loaded into the ejector type work machine.
The receptacle of the ejector type work machine includes a tailgate which prevents material from exiting the receptacle prior to the ejector plate pushing the material out of the rear of the receptacle. The tailgate is moved between a closed position which prevents material from exiting the receptacle and an open position which allows material to exit the receptacle by hydraulic cylinders. A drawback to tailgates that have heretofore been designed is that the hydraulic cylinders are mounted below the receptacle. Mounting the hydraulic cylinders below the receptacle exposes the hydraulic cylinders to the harsh environment of water, dust, mud, and other material that can be sprayed on the underside of the receptacle. In addition, there are situations where it would be advantageous to use the tailgate as a work tool to move material around. Mounting the cylinders below the receptacle prevents the tailgate from being used as a work tool because the cylinders could be damaged by the moving material with the tailgate.
What is needed therefore is a method and apparatus for mounting the tailgate cylinders on the ejector type work machine which overcomes one or more of the above-mentioned drawbacks.
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Moyna John P.
Prillinger Peter F.
Smith Christopher
Young David A.
Bratlie Steven A.
Caterpillar Inc.
Maginot Addison & Moore
Morrison John W.
Smith James R.
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