Tech Briefs

This clamp offers several advantages over a prior toggle-action clamp.

The term "COSMOWRAP" denotes a compact, stiff, remotely actuatable, lightweight, quick-release clamp that could be substituted for the larger, heavier, and more-difficult-to-use toggle-action clamp now used in the space shuttle orbiter docking system (ODS) to perform contingency separations. In comparison with prior hand-operated devices designed for the same purpose, the COSMOWRAP is smaller and lighter in weight, yet offers greater capabilities. The COSMOWRAP (see figure) contains no spring and requires no pre-flight calibration or maintenance. The COSMOWRAP is expected to perform well, not only in the space-shuttle application for which it was originally designed, but also in terrestrial applications. Because the design of the COSMOWRAP reduces the force needed for installation or removal and provides for release by the action of one hand, the replacement of the ODS toggle-action clamp by the COSMOWRAP can be expected to contribute to crew safety in the United States space program and on the International Space Station.

The toggle action clamp, an adjunct to the ODS, carries a high load and is remotely manually released by use of a tether. As its name implies, it includes a toggle-action mechanism. The mechanism includes an actuating lever. Unfortunately, because of time limits, the design of the toggle-action clamp was not optimized before the clamp was produced. As a result, the toggle-action clamp is heavy as well as very large and cumbersome — a circumstance worsened by need for two such clamps on each spaceflight. The combined assembly length of the toggle-action clamps is >32 in. (>81.3 cm) and each toggle-action clamp weighs 22 lb. (a mass of 10 kg). In addition, the operation of the toggle-action clamp is affected by friction in its joints. Because the force needed to operate the toggle-action clamp is greater than that originally expected, a winch tool must be used to perform a release maneuver when the clamp load is high. Moreover, because it is typically necessary to perform pre-flight calibration and checkout, the toggle-action clamp is not only cumbersome but also expensive to use.

The COSMOWRAP is a user-friendly and cost-efficient alternative to the toggle-action clamp and has desirable characteristics not observed in the toggle-action clamp. Among these characteristics are the following:

  • The clamping load is significantly higher at release than at installation.
  • The COSMOWRAP is capable of remote manual release. Its release load is no more than 25 lb. (111 N) [the value required for space missions], although the load on the clamp portion of the COSMOWRAP can approach 104 lb. (44 kN).
  • The clamp can open fully at release to enable separation of previously clamped interfacial components.

Two especially notable features of the COSMOWRAP design are a double-slant interface and an over-center lock-and-release rolling mechanism that provide operational advantages over the toggle-action clamp and enable quick release. Whereas friction in the joints resists operation of the handle in the toggle-action clamp, the COSMOWRAP design utilizes the friction in the joints in its main load path to reduce the release load. At release, the double-slant interface configuration of the COSMOWRAP enables complete and quick severance of load paths; as a consequence, the components of the COSMOWRAP can be made short and compact, thus contributing to an optimized design characterized by minimum weight and maximum stiffness. Other benefits of the COSMOWRAP design are the following:

  • The over-center lock-and-release rolling mechanism enables the COSMOWRAP to lock itself under load.
  • The roller mechanism in the COSMOWRAP is not only less adversely affected by friction than is the corresponding mechanism in the toggle-action clamp; in addition, the COSMOWRAP mechanism includes a setscrew that enables the precise adjustment of the release load.
  • A slide link makes one-hand operation possible.
The COSMOWRAP serves the same purpose as does a toggle-action clamp, but is smaller, stiffer, lighter in weight, more easily operable, and more capable.

Although high-strength-steel components are included in the COSMOWRAP, it could be possible to make some components from aluminum, depending on the magnitude of the load anticipated for the intended application. The required slope of the slant interfaces depends on the finish of interface-bearing surfaces. Once a surface finish and coating have been specified and the corresponding ranges of friction are known, the required slope can be easily determined and verified by simple tests.

Ease of use, a weight-and-space-saving design, and one-handed operation make the COSMOWRAP an attractive addition to the U.S. space program. The COSMOWRAP can be used, for example, to assemble and disassemble a wide variety of highly loaded gasket joints; thus, it can be expected to be suitable for a variety of applications in hazardous environments, not only in outer space but also on Earth (for example, in the repair and construction of pipelines, firefighting, and demolition). The COSMOWRAP can also be used as a quick-release C clamp, jig, or fixture in place of many other lever- and/or toggle-actuated mechanisms.

This work was done by Ted W. Tsai of Johnson Space Center.

This invention is owned by NASA, and a patent application has been filed. Inquiries concerning nonexclusive or exclusive license for its commercial development should be addressed to

the Patent Counsel
Johnson Space Center
(281) 483-0837.

Refer to MSC-22722.

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