Electric heating – Metal heating – By arc
Reexamination Certificate
1998-12-10
2001-05-15
Cherry, Johnny D. (Department: 3652)
Electric heating
Metal heating
By arc
C016S429000, C294S001200
Reexamination Certificate
active
06232576
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains to handling heavy equipment, and more particularly to apparatus for lifting welding machines.
2. Description of the Prior Art
Engine-driven welding machines are large and heavy, and therefore care must be used when handling them. To facilitate moving them, enginedriven welding machines often include a lifting eye that is rigidly fixed to the machine frame. The lifting eye is located such that the welding machine is balanced when lifted by a crane hook or the like. To be useful, the lifting eye must be readily accessable. Normally, that requires that it be outside and above the welding machine top cover.
The presence of a lifting eye on the top of a welding machine has some disadvantages. For example, the lifting eye adds to the overall height of the welding machine. Consequently, larger containers are required for shipping a given number of the machines. In addition, the lifting eye prevents stacking the welding machines one on top of another.
To alleviate the problems associated with fixed lifting eyes, it is known to use moveable components. A commercially available welding machine has a lifting plate that is slidable between raised and lowered positions. One end of the plate has a rather small opening through it. When the lifting plate is in the lowered position, the plate and hole are completely within the machine. The plate can be pulled upwardly to expose the opening for lifting purposes. To retain the plate in the raised position, two screws must be inserted through the plate and an adjoining machine structural member. Conversely, when it is desired to lower the lifting plate, the screws must first be removed. The small size of the lifting plate opening and the requirement of installing and removing screws every time the plate is moved are important drawbacks of the prior lifting plate design.
SUMMARY OF THE INVENTION
In accordance with the present invention, a moveable lifting eye mechanism is provided that is both very robust and easy to use. This is accomplished by apparatus that includes a lifting eye that is guided by a strap.
The lifting eye is comprised of a bail and a bar that connects the stems of the bail. The strap has straight portions with respective free ends that are rigidly secured to a structural member of an object to be lifted. The strap straight portions are spaced apart a distance that guides and allows the bar of the lifting eye to slide easily between them. The strap straight portions are joined at respective second ends by a connector. According to one aspect of the invention, the strap straight portions and connector are integral in the form of a U-shaped strap.
The lifting eye is slidable between a retracted position and an extended position. When the lifting eye is in the retracted position, the bail is mostly below a selected surface of the object, such as a top cover of a welding machine. However, part of the bail remains above the object surface such that there is a small opening between the bail and the object surface. The lifting eye is then out of the way for shipping and storage purposes, but there is sufficient access to the bail for lifting it with a finger. The lifting eye is located against a positive stop when it is in the retracted position.
When the lifting eye is in the extended position, the lifting eye bar is located against the strap connector. In that situation, practically the entire bail is above the selected object surface, such as the welding machine top cover. The lifting eye is then completely accessible for lifting purposes.
Further in accordance with the present invention, the lifting eye is retained in the extended position by a spring that engages the strap. The spring has two legs that are connected by a center section. In use, the spring center section overlies the strap connector. The legs of the spring have respective free ends that terminate in inwardly facing V-sections. The spring V-sections protrude through respective slots in the strap straight portions and lie in the path of the lifting eye bar when it slides between the extended and retracted positions. Inner arms of the spring V-sections support the lifting eye bar when it is in the extended position. Pushing the lifting eye against the inner arms of the spring V-sections resiliently deflects the spring legs apart and enables the lifting eye bar to pass between the V-sections. When the lifting eye bar has passed the V-sections and the lifting eye is in the retracted position, the spring legs return to their undeflected condition.
Gravity maintains the lifting eye in the retracted position until it is intentionally pulled upward toward its extended position. When that occurs, the lifting eye bar contacts the V-section outer arms and deflects the spring legs apart until the bar passes them and is again in its extended position. Then the spring legs return to their undeflected condition. If desired, a bolt can be placed through the straight portions of the strap to positively retain the lifting eye in either its extended or retracted position.
According to another aspect of the invention, the lifting eye is retained in the extended position by a friction force. In one embodiment, a pair of resilient plates are captured in the strap. The plates are generally V-shaped, and their respective apexes are in contact with opposite sides of the lifting eye bar. A friction force is created between the plates and the lifting eye bar in response to a tendency of the lifting eye to slide within the strap.
Other advantages, benefits, and features of the present invention will become apparent to those skilled in the art upon reading the detailed description of the invention.
REFERENCES:
patent: D. 142783 (1945-11-01), Jacobson
patent: 1268124 (1918-06-01), Jennings
patent: 2025149 (1935-12-01), Barkhausen et al.
patent: 2453835 (1948-11-01), Donkin
patent: 5317795 (1994-06-01), Bolton et al.
Owner's Manual—By Miller Electric—Big Blue 400D—Form OM-463V—Jul. 1995.
Cayen Donald
Cherry Johnny D.
Illinois Tool Works Inc.
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