Thumbscrew with automatic torque-limiting feature

Details Thumbscrew with automatic torque-limiting feature Thumbscrew with automatic torque-limiting feature

1999-11-17

2002-04-02

Luebke, Renee (Department: 2833)

Electrical connectors

With coupling movement-actuating means or retaining means in...

Retaining means

C439S923000, C411S007000, C411S353000

Reexamination Certificate

active

06364688

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to thumbscrews utilized to attach cables and cable connectors and, more specifically, to thumbscrews which limit the torque applied to the screw shaft to prevent damage either to the connector or the device to which the connector is attached.
BACKGROUND OF THE INVENTION
Thumbscrews are commonly incorporated into cable connectors on cables used with personal computers, servers, printers and other electronic devices to retain the connector in a connected, mated condition with the mating device connector.
While thumbscrews are very effective for the described retention function, use of a screwdriver is usually necessary to adequately thread or unthread the screws because the screws are located in cramped quarters. The user may not be able to reach or manipulate the screws with his fingers. Unfortunately, a screwdriver easily permits the application of excessive torque and may cause the screw to “bottom” in the receiving member or nut or cause the receiving member to otherwise break. With an over-torqueing of the thumbscrew by a screwdriver or other tool, it becomes very difficult to remove or unthread a screw without damage to the screw, screw head, the mating nut or female threaded member, possibly rendering the connector unusable or unreliable.
In the event of damage to the connected device, it is many times necessary to remove and replace an electronic expansion circuit board in order to repair the damage. This repair results in delays and significant cost.
OBJECTS OF THE INVENTION
It is an object of the invention to limit torque that may be applied to the retaining thumbscrews of a cable connector by a tool or by the user's fingers.
It is another object of the invention to disconnect the drive of a thumbscrew in one direction of rotation.
It is a further object of the invention to positively drive a thumbscrew in a second direction of rotation even after rotational drive of the thumbscrew has been disconnected in a first direction of rotation.
It is an additional object of the invention to disable the drive between a screw member and its driving member, responsive to the amount of axial displacement of the screw member relative to a member fastened by such screw in a tightening direction of drive.
SUMMARY OF THE INVENTION
A threaded shaft for retaining a connector of a cable or the like is driven by a cup-shaped driving member enclosing one end of the threaded shaft. The enclosed end of the screw shaft and the cup-shaped member form a disengageable drive between the cup-shaped member and the screw shaft; disengagement of this drive is controlled by the progressive engagement of the threads on the threaded screw shaft with a female threaded member or nut and the cup-shaped member being restrained against axial movement by interference with a barrier surface, normally the cable connector housing. As the screw shaft becomes more fully threaded into the female member, the driving surfaces of the cup-shaped member and shaft are disengaged and the cup-shaped member ratchets relative to the driven shaft component and does not further drive the shaft in a threadingly rotational direction.
In an unthreading rotational direction, the drive connection is so configured that, the drive connection is effective to rotate the shaft to unthread the shaft from the female threaded connector even though the drive connection is disconnected or disengaged in the threading rotational direction.
Parts breakage is reduced by simply limiting the torque applied to the shaft. Also, the screw may be unthreaded more easily if the screw is not over-torqued during installation. By preventing the bottoming of the screw threads relative to the female threaded member, the screw is less subject to binding and seizure.


REFERENCES:
patent: 4512697 (1985-04-01), Cascini
patent: 5020951 (1991-06-01), Smith
patent: 5449260 (1995-09-01), Whittle
patent: 5544992 (1996-08-01), Ciobanu et al.
patent: 5586852 (1996-12-01), Ganter
patent: 5647758 (1997-07-01), Ichikawa et al.
patent: 6079923 (2000-06-01), Ross et al.
patent: 6082941 (2000-07-01), Dupont et al.
patent: 95/22700 (1995-08-01), None

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