Method and apparatus for pivotally mounting instrumentation on a line

This invention relates to instrumentation packages, and in particular, to an apparatus for pivotally mounting an instrument package to a line, such as a balloon tether line, to enable the instrument package to freely rotate about the line. The instrument package mounting apparatus comprises an axle that serves to eliminate the need to wrap a tether line about the axle. In particular, the axle comprises a cylindrical solid configured with a slot extending from the outer surface of the axle to a substantially central axis thereof, the slot being capable of receiving the tether line. Juxtaposed to this slot and located substantially centered about the substantially central axis of the axle is a rectangular shaped interior channel that functions to receive a pinch bar comprising a substantially rectangular shaped tapered bar. The tapered pinch bar is inserted into the channel formed in the axle and operates to frictionally secure the tether line and the axle. The friction to secure the tether line in the slot, as held in place by the tapered pinch bar is generated by a compression fit formed as the tapered pinch bar is inserted into the interior channel of the axle.