Land vehicles: dumping – Tilting – With cover or endgate control
Reexamination Certificate
1999-07-21
2001-01-09
Dayoan, D. Glenn (Department: 3612)
Land vehicles: dumping
Tilting
With cover or endgate control
C298S02300C
Reexamination Certificate
active
06170916
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the field of operating assemblies to raise and lower the tailgates of dump trucks and semi-trailers having a mechanism to raise the front end of the trailer for unloading the contents through the open rear wall of the trailer when the tailgate has been raised.
BACKGROUND OF THE INVENTION
One of the problems in unloading dump trucks and trailers having a front end lift mechanism is to spread the contents evenly while being unloaded and as the truck or trailer is being moved forwardly at the proper speed. Prior art mechanisms for opening and closing the tailgates made it difficult to control the amount of opening needed to achieve even spreading of the contents while being unloaded. The present invention provides an improved tailgate operating assembly.
SUMMARY OF THE INVENTION
The tailgate operating assembly in accordance with this invention provides a hydraulic cylinder mounted horizontally along each opposite side wall of the trailer cargo box, with the plungers thereof facing rearwardly. One end of a lever or armature is connected to the outer end of the plunger of each cylinder, each lever or armature being pivotally hinged to respective ones of the opposite side walls of the cargo box, and the opposite operating end of each lever or armature is connected to respective facing portions of the upper edge of the tailgate. When the plungers are moved toward their extended positions, the tailgate begins to raise. When the plungers are moved toward their retracted position the tailgate begins to close. A pressure release mechanism is provided for each of the hydraulic cylinders to facilitate retraction of the pistons and corresponding closure of the tailgate. The pressure release mechanism consists of a pressure release port in each of the horizontally mounted hydraulic cylinders, located at the most upwardly facing portion of the cylindrical wall and near the plunger end of the cylinder. A pressure release conduit is connected at one end to each of the pressure release ports of the respective cylinders and the opposite discharge ends of each pressure release conduit extend through an aperture in the respective side walls of the cargo box for discharge into the cavity of the box. Thus, the gravity weight of the tailgate as it moves toward its closed position can more freely urge the plungers and pistons of the respective cylinders to their retracted positions when the internal pressure of the cylinders is released.
REFERENCES:
patent: 3322464 (1967-05-01), Merritt et al.
patent: 3860288 (1975-01-01), Martin et al.
patent: 5143496 (1992-09-01), Smith et al.
patent: 5281074 (1994-01-01), Mashuda
patent: 5518287 (1996-05-01), Totani
Carpenter Scott
Dayoan D. Glenn
Kettelson Ernest
L&M Manufacturing, Inc.
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