Tektronix, Inc.

John S Lyford

Jonathan E Myers

James H McGrath, Jr

Steve U Reinhold

A stackable, recessed, locking, insulated thumbscrew for connecting modules together in a stack such that removal of one module from the stack does not loosen other modules in the stack has an insulated knurled cap that fits over the end of a main screw body. The main screw body has an interior threaded end and an exterior threaded end, with the knurled cap slidable over the interior threaded end by means of a bayonet pin on the main screw body and corresponding bayonet slot in the knurled cap. A cap spring is captured between a retainer flange integral with or retainer ring mounted on the interior threaded end adjacent the exterior threaded end and the knurled cap to apply pressure to the knurled cap. In a raised position the knurled cap may be readily grasped for manual screwing and unscrewing of the thumbscrew to add or remove a module from the stack. In a recessed position where the knurled cap is depressed and rotated the knurled cap extends sufficiently so that locking surfaces on the cap engage a locking feature in an upper module so that when the upper module is removed by unscrewing the upper thumbscrew, the lower thumbscrew is restrained from turning, thus keeping the lower module securely fastened in the stack.

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Portland, OR, United States of America

John S Lyford