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Positive Drive and Release Capstan Clutch

IP.com Disclosure Number: IPCOM000089773D
Original Publication Date: 1977-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 3 page(s) / 31K

Publishing Venue

IBM

Related People

Sebrosky, RA: AUTHOR [+2]

Abstract

In some typically used spring clutch designs, the spring is caused to wrap down on a driving capstan. Some of these designs further include an initial preload of clutch spring in the direction of windup. This preload windup in the clutch spring causes a skewing of the spring coils with relationship to the capstan which they surround. Also, contact of the spring with the capstan, when it is deactivated or in an idling mode, may result from the skewing of the spring coils. The eccentricity in such a system is unavoidable, and the assembly of such a mechanism is critical in order to prevent unwanted actuations of the clutch or unreliable release of the clutch.

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Positive Drive and Release Capstan Clutch

In some typically used spring clutch designs, the spring is caused to wrap down on a driving capstan. Some of these designs further include an initial preload of clutch spring in the direction of windup. This preload windup in the clutch spring causes a skewing of the spring coils with relationship to the capstan which they surround. Also, contact of the spring with the capstan, when it is deactivated or in an idling mode, may result from the skewing of the spring coils. The eccentricity in such a system is unavoidable, and the assembly of such a mechanism is critical in order to prevent unwanted actuations of the clutch or unreliable release of the clutch.

The figure shows an improved capstan clutch which relies on an initial spring preload for disengagement from the capstan surface. This design also allows for a positive engagement of the clutch, but zero contact between any spring coil with the capstan when the clutch is disengaged. Concentricity between the interior diameter of the spring and the exterior diameter of the capstan is established for the clutch with the spring deactivated.

In the figure, capstan 1 is continuously driven by a motor (not shown). The clutch surface of capstan 1 is labeled 2. Concentric with surface 2 is an interior surface of the spiral wound spring 3. The exterior diameter of spring 3 is captured within a cylindrical shell or wall 4, and the end 5 of spring 3 engages a slot 6 in the wall of the shell 4. The opposite end 7 of the spring can be moved to create frictional contact between the spring and the capstan surface 2 to cause actuation of the clutch. Various actuation means may be utilized, and it will be understood that moving the end 7 of the spring toward the capstan will cause frictional contact between the interior surface of the spiral spring and the exterior surface of the capstan 2, which will cause windup of the spring a...