What Is Rack & Pinion?

The rack and pinion is a gear assembly that converts linear motion to rotary movement. It also can convert rotary movement to linear motion. A rack and pinion assembly is a mechanical system that allows these movement changes.

Rack

The rack portion of a rack and pinion system is a piece of flat metal with gear teeth. The design is such that the rack and pinion teeth engage each other. The rack provides the linear movement of the assembly.

Pinion

The pinion of the assembly is a round gear at the end of a shaft, and meshes with the rack. It provides the rotary movement of the design.

Rack and pinion

The two parts of a rack and pinion work together. Depending on whether or not the rack or the pinion is fixed will determine how the parts of the assembly will move.

Linear Movement

To allow linear movement, the pinion portion of the assembly is fixed. When the pinion rotates, the rack moves in the appropriate direction. Parts attached at the end of the rack cause other actions to take place.

Rotary Movement

When the rack moves, the pinion gear rotates around its shaft. The pinion can rotate either direction if needed.

References

• Carnegie Mellon: Introduction to Mechanisms
• Technology Student: Rack and Pinion Gear Systems