These couplings are used where shafts intersect at any angle or where pivoted
members must be driven. If there is an offset in the two shafts, or if one or
both shafts must change location during operation, two of these couplings are
used, and one is fitted with a splined joint mating with the connecting
intermediate shaft to allow axial movement. Pit and Quarry
Source:
Dictionary of Mining, Mineral, and Related Terms