parallel motion
Noun
Meaning
parallel motion
(engineering) Any linkage by which circular motion may be changed into motion in a straight line.
Examples
He acquired a taste for parallel motion in fifths, fourths and octaves from medieval music, and an appreciation for figuration and arabesque from the Baroque masters.
Its distinguishing factor is that the parts did not have to move only in parallel motion, but could also move in oblique, or contrary motion.