Remote Servo rack and pinions are available in (8) ratios from 1-3/4" (slow) to 3-1/4" (fast). Rack speed is measured in inches per turn. If you turn the pinion (1) time the rack shaft will move between 1-3/4" (slow) and 3-1/4" (fast). That number is stamped on the front of the housing next to the grease fitting. The most popular center distance is 18-1/4".
