3-D Sprags and Rollers
EVA Roller Wrench

The three-dimensional (3-D) sprags have been used as a candidate robotic arm brake mechanism for the University of Maryland Ranger Telerobotic Shuttle Experiment, which is scheduled for flight on the Space Shuttle in September 2000. This brake is approximately one-half the volume and one-half the mass of a conventional roller locking brake for the same rated holding torque.

There are two NASA/Goddard Space Flight Center Director's Discretionary Fund projects investigating various applications of 3-D sprags and rollers.

• Next Generation Space Telescope cold temperature microminiature actuators: voice coils that use 3-D sprags to lock with power off
• Space qualification of the 3-D roller and its use in place of the ratchet in commercial and extravehicular activity wrenches

The 3-D sprag technology is being transferred to private industry, which is being fed back to NASA and is proving to be of significant benefit.