Gear racks are utilized to convert rotating movement into linear motion. A gear rack has straight teeth cut into one surface of a square or round section rod with a pinion, which is a small cylindrical gear meshing with the gear rack. There are many ways to use gears.
As a mechanical element to transfer rotary into linear motion, gear racks are often compared to ball screws. The advantages of a gear rack is its mechanical simplicity, large load carrying capacity, no limit to the length.