Compact, Stiff, Lightweight, Quick-Release Clamp
- Monday, 27 August 2007
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.