Latching devices have been developed to provide electrical connections, secure mechanical and thermal connections, and optical alignment for mounting electronically controlled cameras on the spaceborne laboratory apparatus described in the preceding article. Traditionally, the installation of such a camera or a similar instrument has been a time-consuming task that involved tightening of multiple fasteners to specified torques, making separate electrical connections, and use of special tools. The present latching devices are designed for quick connection and quick disconnection by simple manual hand motions; no tools are needed. These latching devices could also be used on Earth in numerous industrial and scientific applications to provide electrical, mechanical, thermal, and/or optical interconnections that can be made and broken quickly and reliably, without tools.
Each latching device comprises two mating subassemblies (see figure). The operation of the latching device depends on a unique combination of threaded parts. The inner spring-loaded handle is connected to the rods, which are not free to rotate. A single high-pitch thread on each rod engages a nut that is free to rotate but not to translate along its axis of rotation. A boss on each nut engages a lower-pitch groove in its mating receptacle, each of which is free to rotate with respect to the handle.
To connect the two subassemblies, one simply squeezes together the two spring-loaded handles on one subassembly, inserts the rods and nuts protruding from that subassembly into mating receptacles on the other subassembly, then releases the handles. The initial squeezing of the handles causes the nuts to rotate to an angular position in which the bosses on the nuts are aligned with the openings to the grooves in the receptacles. The release of the handle causes the nuts to rotate in a direction to make the bosses slide along the grooves deeper into the receptacles, thereby drawing the two subassemblies together at a common surface. In the original application, the contact at the common surface brings the camera into alignment with an optical reference surface. The force clamping the two subassemblies together is generated by the spring and multiplied by a mechanical advantage proportional to the ratio between the pitch of the thread and the pitch of the groove. By use of low-friction coating material on the threads, grooves, and bosses, the achievable clamping force can be made to approach the ideal clamping force more closely.
This work was done by Malcolm Robbie of Analex Corp. for Lewis Research Center.
Inquiries concerning rights for the commercial use of this invention should be addressed to
NASA Lewis Research Center
Commercial Technology Office
Attn: Tech Brief Patent Status
Mail Stop 7 3
21000 Brookpark Road
Refer to LEW-16528.