Rack gears are straight bars with gear teeth running along one side into the gear teeth of a pinion. Usually, the teeth are straight (spur rack). Rack and pinion are sometimes used instead of an trapezoidal threaded shaft and nut to move a machine head in a back and forth motion.The spur rack is made of 45# steel, which has high hardness, strength, and strong deformation resistance, it is more durable, longer lasting, and easier to process, install, and debug.Racks are used to convert rotary motion into linear motion. The straight teeth of the rack are cut into one face of the square or circular section of the rod and fit with the pinion, which has the characteristics of mechanical simplicity, high load-carrying capacity, and unlimited length.
eBay