Traversing hoists – Having clutch or variable speed transmission
Reexamination Certificate
1997-04-01
2001-06-12
Brahan, Thomas J. (Department: 3652)
Traversing hoists
Having clutch or variable speed transmission
C254S299000, C254S303000
Reexamination Certificate
active
06244449
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to cranes that use one or more load hoist lines to lift loads. In cranes of this type, each load hoist line is wrapped, or reeved, around a separate load hoist line drum. The drum is rotated to either pay out or retrieve the load hoist line drum. A drum drive assembly is used to rotate the drum during normal crane lifting operations.
Under certain circumstances, it is desirable to disconnect the drum from the drum drive motor so that it may rotate freely. For example, when a crane is used to repeatedly hoist objects a long vertical distance, it may be faster and/or more economical to allow the influence of gravity acting upon the hook block to pull the load hoist line off of the load hoist line drum between lifts. Once the hook block has been lowered back to the ground, the load hoist line drum is reconnected to the drum drive motor so that the load hoist line can be used to hoist the next object.
One of the purposes of the present invention is to provide a drum drive assembly which will permit the quick, easy, and safe disconnection of the load hoist line drum from the drum drive motor.
SUMMARY OF THE INVENTION
The present invention provides a drum drive assembly for cranes which use a load hoist lines reeled onto a load hoist line drum to lift loads. The drum drive assembly allows the load hoist line drum to be disconnected from the drum drive motor to permit the load hoist line drum to rotate independent of the drum drive motor. This permits the load hoist line to spool, or “free fall,” off of the load hoist line drum under the influence of gravity.
The drum drive assembly of the present invention comprises one or more motors for rotating the load hoist line drum to either pay out or reel in the load hoist line; a brake for slowing, stopping or preventing the rotation of the load hoist line drum; and a jaw clutch which may be disengaged to permit the load hoist line drum to rotate independently of the motor. The preferred jaw clutch comprises a drive clutch plate and a driven clutch plate. The drive clutch plate and the driven clutch plate engage each other to connect the motors to the load hoist line drum and disengage from each other to disconnect the motors from the load hoist line drum.
The preferred embodiment of the invention includes features in addition to those listed above. Moreover, the advantages over the current art discussed above are directly applicable to the preferred embodiment, but are not exclusive. The other features and advantages of the present invention will be further understood and appreciated when considered in relation to the detailed description of the preferred embodiment.
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Brahan Thomas J.
Brinks Hofer Gilson & Lione
Manitowoc Crane Group, Inc.
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