Racks (straight gears)

General: Racks are straight gears that are used to convert rotational motion to translational motion by means of a gear mesh. (They are in theory a gear with an infinite pitch diameter). In theory, the torque and angular velocity of the pinion gear are related to the Force and the velocity of the rack by the radius of the pinion gear, as is shown below:

Perhaps the most well-known application of a rack is the rack and pinion steering system used on many cars in the past.
Limitations: Limited usefulness. Difficult to find.
Advantages:The only gearing component that converts rotational motion to translational motion. Efficiently transmits power. Generally offers better precision than other conversion methods.