Mechanisms: Slotted Yoke Drive

This week we were assigned to investigate mechanisms and write about our favorite. My favorite mechanism is the ¨Slotted Yoke Drive¨, it´s my personal favorite because it at first glance almost seems counter intuitive because it uses the rotational movement and converts it to a horizontal movement.

There are two main components to the slotted yoke drive, the circular disk base with a protruding part that gets inserted to the slotted component and the slotted component with two rods at the end that causes the ¨drive¨ motion. There are two pieces that go over each rod and keeps the rods from moving out of it´s straight path.

The horizontal ¨drive¨ movement is created by the circular disk and is transferred to the slotted component via the protruding part on the edge of the circular disk. Because the disk is circular the velocity of the slotted component is constantly changing, but this circular motion is what is distinctive about the slotted yoke drive. The protruding rod on the disk spends half of it´s time on the edges of the slot where movement is maximum at the other half traveling up or down the slot, changing it´s direction giving it the trademark back and forth motion.

Optically this mechanism is really interesting because the circular motion of the disk is hidden behind the optical illusion ¨up and down motion¨ of the protruding rod in the slot but ultimately turns into a horizontal motion. The real life application of the slotted yoke drive, or the ¨scotch yoke¨ is in high pressure oil and gas pipelines or for zinc baths (pictured in the photo below)