Movement No. 119 converts uniform rotary motion of a pinion into reciprocating rectilinear motion of a bar carrying an oblong endless rack. The rack is formed as a closed oval or oblong loop with teeth on both the top and bottom edges. A continuously rotating pinion engages the top teeth of the rack on one pass, driving the rack bar in one direction. As the pinion’s shaft — guided by a slotted bar — moves up or down at the ends of the oval, the pinion transitions to engage the bottom teeth, now driving the rack bar back in the opposite direction. This alternating top-and-bottom engagement produces smooth, continuous reciprocating motion without any separate reversal mechanism. The slotted bar guides the pinion shaft through this transition at each end of the stroke, making the reversal seamless and automatic from a single steady rotary input.
119. Reciprocating rectilinear motion of the bar carrying the oblong endless rack, produced by the uniform rotary motion of the pinion working alternately above and below the rack. The shaft of the pinion moves up and down in, and is guided by, the slotted bar.