What is the name of the unit that prevents a nose wheel from vibrating or oscillating?

The correct answer is the shimmy damper, which plays a crucial role in maintaining the stability of the nose wheel during taxiing and landing. When a nose wheel experiences vibrations or oscillations—often referred to as "shimmy"—the shimmy damper functions to absorb these oscillations through hydraulic or mechanical means. This device helps provide a smoother ride and ensures that the nose wheel remains firmly controlled, enhancing safety and passenger comfort.

In contrast, other options serve different purposes. A torque link is primarily responsible for controlling the angle and movement of the landing gear during extension and retraction, and it helps maintain alignment. A stabilizer bar is a term more commonly associated with wing structures or control surfaces, rather than landing gear. A shock absorber, while important for smoothing out impacts from landing or taxiing, does not specifically address the oscillatory movement that the shimmy damper is designed to combat.