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Space Systems Lab
University of Maryland Development of a Ratchetless Wrench for Extravehicular Activity

The idea for a "ratchetless" wrench came about because of an invention by NASA/Goddard Space Flight Center (GSFC) engineer John Vranish. He was looking for an alternative to the two-dimensional (2-D) sprags that were being considered for use in space. His idea was to groove the races and round the edges of the sprags, creating a three-dimensional (3-D) sprag. John took his sketches to GSFC Aerospace Engineering Techician Mike Wade who developed the idea to replace the traditional ratchet with 3-D sprags. The Space Systems Laboratory (SSL) is extending this to extravehicular activity (EVA) tools for the astronauts.

Follow the links below to learn more or feel free to contact the lead engineer for the EVA tools project, Brian Roberts.

3-D Sprags and Rollers

Learn more about the advantages of John's 3-D sprags over their 2-D counterparts and the additional
innovations that have resulted from the original technology.

Commercial 3-D Roller Wrench

Find out more about the work that has been going on with the commercial wrench.

EVA 3-D Roller Wrench

Read more about how the SSL is working on the development of a "ratchetless" EVA wrench and the tests we conducted on NASA's Reduced Gravity Flying Laboratory, in their Neutral Buoyancy Laboratory, and even on the Space Shuttle.

Articles, Publications, and Presentations

A complete list of all of the papers written about 3-D sprags and rollers, the "ratchetless" wrench, and articles that have appeared in magazines and newspapers.

Awards and Recognitions

3-D sprags and rollers have been recognized by many groups.

Project Funding and Support

This project has had both financial and logistical support from many different groups.

Project Personnel

A project of this magnitude involves many people from different walks of life. Take a look at those who have made the wrench project possible.

Other Applications for 3-D Sprags and Rollers

There are many other places that 3-D sprags are being used.

Links to Other Sprag Resources

Who to Contact for More Information

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