This “Double Scotch,” Scotch Yoke steam engine was built in the mid-1990s by Roger Butzen of Texas, and loaned to the Miniature Engineering Craftsmanship Museum as part of the Engine Collection of Paul and Paula Knapp. Mr. Butzen’s tiny Double Scotch engine is just 3”-long, 5”-wide, 3”-high, and weighs 2 lbs.
The Scotch yoke is a reciprocating motion mechanism, converting the linear motion of a slider into rotational motion, or vice versa. The piston or other reciprocating part is directly coupled to a sliding yoke with a slot that engages a pin on the rotating part.