Patent Application
20130257135
This invention relates in general to mechanisms for raising and lowering a tailgate provided on a dump box of a dump truck, trailer, or similar vehicle. In particular, this invention relates to a non-circular cylinder assembly for raising and lowering such a tailgate that is pivotably supported on the dump box.
A typical dump truck includes a dump box that is movable (usually by pivoting) between a lowered position (for storing and transporting items) and a raised position (for dumping the items out of the dump box). A typical dump box includes a floor, a pair of side walls, a front wall, and an open rear end for accomplishing this function. Frequently, the open rear end of the dump box includes a pair of upstanding corner posts that are each formed from a hollow rectangular member. A tailgate is supported on the side walls of the dump box adjacent to the open rear end for pivoting movement between a closed position (wherein the tailgate closes the open rear end of the dump box for facilitating the storing and transporting of the items therein) and an opened position (wherein the tailgate is pivoted away from the open rear end of the dump box for facilitating the dumping of the items out of the dump box).
In many instances, the tailgate is affirmatively moved between the opened and closed positions by means of a cylinder (typically a pneumatic cylinder) that extends between the dump box and the tailgate. When the cylinder is extended, the tailgate is pivoted away from the open rear end of the dump box to the opened position. When the cylinder is retracted, the tailgate is pivoted toward the open rear end of the dump box to the closed position. In this manner, the operation of the cylinder controls the movement of the tailgate between the opened and closed positions.
In the past, the cylinder has typically been provided on the dump truck in one of two locations. In a first generally vertical orientation, a cylinder has been located within either or both of the hollow upstanding corner posts provided on the open rear end of the dump box. This generally vertical orientation is desirable because it does not expand the overall width of the vehicle, which can be limited by practical considerations or by regulation. However, the internal space that is available within each of these corner posts is limited, thus limiting the size of the cylinder that can be provided within each of the corner posts (and, as a result, the amount of force that is available to move the tailgate between the opened and closed positions) is relatively limited. In a second, generally horizontal orientation, a cylinder has been located on the outside of either or both of the side walls of the dump box. This generally horizontal orientation is desirable because it is simple and inexpensive to install. However, as mentioned above, it does undesirably expand the overall width of the vehicle. Thus, it would be desirable to provide an improved mechanism for raising and lowering a tailgate provided on a dump box of a dump truck, trailer, or similar vehicle that avoids these problems.
This invention relates in general to an improved mechanism for raising and lowering a tailgate provided on a dump box of a dump truck, trailer, or similar vehicle. The mechanism includes a dump box having an open end and a tailgate supported on the dump box for movement between a closed position, wherein the tailgate closes the open rear end of the dump box, and an opened position, wherein the tailgate is spaced away from the open end of the dump box. A cylinder assembly extends between the dump box and the tailgate. The cylinder assembly includes a cylinder and a piston that is able to move in an axial direction relative to the cylinder for selectively moving the tailgate between the closed and opened positions. The piston has a non-circular cross-sectional shape.
The invention also relates to a vehicle that includes a frame and a dump box having an open end. The dump box is supported on the frame for movement between a lowered position for storing and transporting items and a raised position for dumping the items out of the dump box. A tailgate is supported on the dump box for movement between a closed position, wherein the tailgate closes the open rear end of the dump box, and an opened position, wherein the tailgate is spaced away from the open end of the dump box. A cylinder assembly extends between the dump box and the tailgate for selectively moving the tailgate between the closed and opened positions. The cylinder assembly includes a cylinder and a piston that is able to move in an axial direction relative to the cylinder for selectively moving the tailgate between the closed and opened positions. The piston has a non-circular cross-sectional shape.
Various aspects of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings.
Referring now to the drawings, there is illustrated in
As more clearly shown in
To open the tailgate 17 of the prior art dump box 11, the cylinder assembly 20 is actuated in a conventional manner to extend the piston rod 22 from the cylinder 21. As a result, the tailgate 17 of the prior art dump box 11 is caused to pivot from a closed position to an opened position. To close the tailgate 17 of the dump box 11, the cylinder assembly 20 is actuated in a conventional manner to retract the piston rod 22 within the cylinder 21. As a result, the tailgate 17 of the prior art dump box 11 is caused to pivot from the opened position to the closed position.
Referring now to
A cylinder assembly, indicated generally at 40, in accordance with this invention is provided within each of the hollow rectangular members of the corner posts 36 of the dump box 31 for moving the tailgate 37 between the opened and closed positions. As will be explained in detail below, each of the cylinder assemblies 40 has a non-circular cross sectional shape. The structure of one of the non-circular cylinder assemblies 40 is illustrated in detail in
To open the tailgate 37 of the dump box 31, the non-circular cylinder assemblies 40 are actuated to extend the piston rods 42a from the respective cylinders 42. As a result, the yoke 44 is similarly extended, causing the tailgate 37 of the dump box 31 to pivot from a closed position to an opened position. To close the tailgate 37 of the dump box 31, the non-circular cylinder assemblies 40 are actuated to retract the piston rods 42a within the respective cylinders 42. As a result, the yoke 44 is similarly retracted, causing the tailgate 37 of the dump box 31 to pivot from the opened position to the closed position.
As best shown in
The non-circular shapes allow each of the cylinder assemblies 40 to occupy a larger amount of cross-sectional space within the respective rectangular corner posts 36 than conventional cylinder assemblies 20 having circular cross-sectional shapes would be able to occupy. This is particularly true in the case of the corner post 36 having a rectangular cross-section. The maximum size of a prior art circular cylinder assembly 20 would be limited by the smallest dimension of the rectangular corner post 36, while the non-circular cylinder assembly 40 will occupy more of the interior space of the corner post 36. This allows a relatively larger non-circular cylinder assembly 40 to be installed within the corner post 36, which can provide more force than the prior art circular cylinder assembly 20 for a given size of the corner post 36.
As shown in
The principle and mode of operation of this invention have been explained and illustrated in its preferred embodiments. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.
