Handling: hand and hoist-line implements – Spacing hoist bar or frame
Reexamination Certificate
2000-06-27
2001-10-02
Lillis, Eileen D. (Department: 3652)
Handling: hand and hoist-line implements
Spacing hoist bar or frame
C294S074000, C294S081500
Reexamination Certificate
active
06296288
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable
REFERENCE TO A “MICROFICHE APPENDIX”
Not applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to lifting apparatus and accessories, and more particularly to an improved spreader bar lifting apparatus for use with cranes and other lifting devices that use slings. Even more particularly the present invention relates to an improved multi-part spreader bar arrangement that includes a plurality of connectable sections including at least a pair of bar sections and a pair of end members, and wherein the detachable connections between the sections are provided with annular load bearing faces that carry a majority of the axial compressive load during use.
2. General Background of the Invention
Spreader bars are commonly used in industry for lifting large objects with a single hook that is attached to the crown block and lift cables of a crane. A lifting hook is commonly provided with a pair of slings that depend from the crane hook at angles in a bridle fashion, each of the slings connecting to an end portion of the spreader bar. Parallel, depending lift lines are then suspended from the end portions of the spreader bar downwardly to the load that is to be lifted. An example of a spreader bar that has been patented can be seen in my prior U.S. Pat. No. 4,397,493, and entitled “Spreader Bar Assembly”.
One of the problems with spreader bars is that of sizing the spreader bar to meet a particular load. Some devices have attempted to provide telescoping sections in order to adjust the spreader bar to different lengths so as to accommodate different loads. Such a telescoping, locking spreader bar operates well for relative light loads of a few thousand pounds. However, in the lifting of extremely heavy objects such as, for example, 25-50 tons, a much more rugged construction is required.
Another problem that faces the user of a spreader bar is that of transporting the bar from one place to another at a construction facility, fabrication yard, plant, shop, or the like. Most spreader bars are extremely heavy when compared to the strength of an average worker. To lift a very heavy object, one has typically needed a very heavy spreader bar. This creates a hazardous condition when workers attempt to move a very heavy spreader bar from one location to another.
BRIEF SUMMARY OF THE INVENTION
The present invention provides an improved spreader bar apparatus that can lift very heavy loads and at the same time be constructed of relatively lightweight material so that a high ratio is provided of load capacity to spreader bar weight.
This solves the problem of providing a very high capacity spreader bar that can be moved from one location to another by a worker or a few workers and avoiding the risk of injury.
The present invention provides a spreader bar apparatus of improved construction that can be disassembled for transport to remote locations using less expensive transportation means such as parcel service, mails, or the like.
The present invention provides an improved spreader bar apparatus that is constructed of a plurality of bar sections and a plurality of end members that are attachable end-to-end to form a single, rugged spreader bar assembly.
In the preferred embodiment, the plurality of bar sections and end members are attached using removable (preferably threaded) connections to assemble the bar sections and end members end-to-end.
In order to prevent substantial stress at the interface between one threaded section and another, the present invention provides transverse annular faces for transferring axial load along the bar central axis and in between the connected bar sections and bar end members. These load transfer faces preferably carry at least half of the load (and preferably substantially all of the load) so that the threads are not damaged during use.
The spreader bar apparatus of the present invention thus provides an improved spreader bar apparatus having a load carrying capacity and a bar weight, with the ratio of the load carrying capacity to the bar weight being between about 800 to 1 and 1200 to 1.
The bar and bar end members are preferably of a material having a density of between about 150 and 200. In the preferred embodiment, the bar sections and bar end members are of an aluminum material or an aluminum alloy. A carbon composite could also be used.
The interconnections between bar sections and end members is preferably a threaded type connection. However, other types of detachable connections can be used to assemble bar sections together and end members to bar sections such as, for example, bayonet-type connections or taper lock or wedge lock type connections.
The present invention provides an improved spreader bar apparatus with annular load carrying faces that can in fact carry substantially all of the axial load in the bar during a lift, thus insulating the connecting portions (for example threads) from substantial stress during the lift.
The apparatus of the present invention includes end members that have sling receiving portions for enabling slings to be rigged to the bar end members.
REFERENCES:
patent: 2730398 (1956-01-01), Huested
patent: 2820661 (1958-01-01), Koon et al.
patent: 3519302 (1970-07-01), Orenstein
patent: 3709548 (1973-01-01), Hogshead
patent: 4397493 (1983-08-01), Khachaturian et al.
patent: 4538849 (1985-09-01), Khachaturian et al.
patent: 4909555 (1990-03-01), Blasi
patent: 5603544 (1997-02-01), Bishop et al.
patent: 5716088 (1998-02-01), Chander et al.
patent: 5863085 (1999-01-01), Khachaturian
patent: 209347 (1957-01-01), None
patent: 1101157 (1968-01-01), None
Chin Paul T.
Garvey, Smith, Nehrbass & Doody LLC
Lillis Eileen D.
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