Handling: hand and hoist-line implements – Grapple – Load shifting
Reexamination Certificate
1999-12-28
2001-11-27
Krizek, Janice L. (Department: 3652)
Handling: hand and hoist-line implements
Grapple
Load shifting
C294S067500, C414S783000
Reexamination Certificate
active
06322117
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to lifting tools. More particularly, the present invention relates to a lifting tool for safe, 105 degree, off-center rotation of large, heavy objects.
BACKGROUND OF THE INVENTION
It is often necessary to lift large, heavy objects during a manufacturing process, such as, for example, during the process of painting steel enclosures (known as “tanks”) for pad mounted transformers. These large, usually rectangular tanks can be painted in an automatic paint facility using the following process, for example.
The tanks are placed one at a time onto a carrier rack that can hold up to four tanks. The carrier rack can be adapted to be carried via a conveyor system to a paint vat, into which the carrier rack is dipped along with the tanks. Preferably, the tanks are oriented on the carrier rack to allow good coverage as they pass through the painting operation. For example, the tanks can be oriented horizontally (i.e., with one of the four side faces facing downward) by placing them on horizontal arms of the carrier rack.
Typically, the tanks are delivered to the conveyor system on a towed cart. To minimize the size of the cart needed, the tanks are positioned on the cart vertically (i.e., with the top or bottom face facing downward). Thus, not only must each tank be lifted off of the cart and onto the carrier, but each tank must also be rotated by about 90 degrees at the same time. Similarly, the painted tanks must be taken from the carrier, rotated by about 90 degrees, and moved back onto the cart.
As a tank typically weighs more than 50 pounds (and frequently up to as much as 100 pounds or more), a tank is too heavy and too large for an ordinary person to move from the cart to the carrier, or vice versa, without the aid of a lifting tool. U.S. Pat. No. 6,209,938 discloses and claims a lifting tool for safe 90 degree rotation of large heavy objects.
In certain applications, however, it is necessary to rotate the object by more than 90 degrees while lifting and moving the object from one location to another. For example, in the painting process described above, the arms of the carrier rack onto which the tanks are to be placed may not be horizontal. In such circumstances, it is often necessary to rotate the tank by as much as 105 degrees during the lifting and moving process. The lifting tool described in U.S. Pat. No 6,209,938, while suitable for 90 degree rotation, is not optimal for rotation in excess of 90 degrees. Thus, there is a need in the art for a lifting tool that can aid a person in lifting and moving large, heavy objects, while rotating the objects up to 105 degrees.
SUMMARY OF THE INVENTION
The present invention satisfies these needs in the art by providing lifting tools for safe, 105 degree, off-center rotation of large, heavy objects. The lifting tool uses the weight of the object itself to create an opposing rotational force nearly equal to the rotational force acting at the center of gravity. This stabilizes the object, and thus enables a person to rotate the object safely, as if the object were nearly balanced at the point of rotation.
A lifting tool of the invention includes a bar that can be positioned generally parallel to a centerline of the object, and first and second clamps that are coupled to first and second ends of the bar, respectively. The clamps can be rotatably coupled to the bar, or slidably coupled thereto. The clamps are adapted to secure the tool to edges of the object.
The tool also includes a pivot arm that is rotatably coupled to the bar, which allows the object to be lifted, rotated up to 105 degrees, moved, and then set down. The pivot arm includes a first pair of chain sprockets disposed along a length thereof. A second pair of chain sprockets is coupled to the second chain sprocket via a common shaft. A pair of chain segments are attached to the pivot arm, and engage each of the second pair of chain sprockets. A first end of the pivot arm can be coupled to a hoist hook, for example, via a chain that engages the first and second chain sprockets, and is coupled to the bar at a point between the clamps.
As the object is rotated and the pivot arm moves relative to the bar, the chain rotates the sprockets. The second pair of sprockets, along with the sprocket from the first pair to which they are coupled, move along pivot arm, thereby minimizing the component force as the object rotation passes through 90 degrees. This reduction in component force enables the user to continue to rotate the object through angles greater than 90 degrees.
REFERENCES:
patent: 1712870 (1929-05-01), Coe
patent: 2399360 (1946-04-01), Lacey
patent: 2448124 (1948-08-01), Roy
patent: 3436116 (1969-04-01), Anderson
patent: 4595225 (1986-06-01), Kemble et al.
patent: 6209938 (2001-04-01), James, Jr.
patent: 1207913 (1960-02-01), None
Drawings: (2 sheets) Lifting Tool for Safe 90 Degree Rotation: original concept applied to Vacuum Lifting Tool by F. James, 1991.
Drawings (1 sheets): Vacuum Handling Device Interlock Schematic & Adjusting Instructions, D.W. Zimmerman Mfg., Inc., 1991.
Drawing (1 sheet) Small Tank 90 Degree Rotating Grab—Air Control Arrangement, ABB Power T&D Company Inc., Aug. 6, 1991.
Drawings: (2 sheets) Side Elevation of Vacuum Lifting Tool Prior to Modification for Safe 90 Degree Rotation—Goodyear “Ortec” (1991); (Sh 1 of 2) Plan View of Vacuum Lifting Tool Prior to Modification for Safe 90 Degree Rotation, 1991 (Sh 2 of 2).
ABB T&D Technology Ltd.
Krizek Janice L.
Washburn Woodcock
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