Steering systems — which component turns rotary input into lateral linkage motion? In a typical steering linkage, which component primarily converts steering wheel rotation into the lateral motion that ultimately steers the road wheels?

Introduction / Context:
Understanding the function of each steering component helps in diagnosing play, noise, and alignment issues. The goal is to identify where rotational motion becomes controlled linear (or angular-to-lateral) motion to turn the wheels.

Given Data / Assumptions:

• Conventional rack-and-pinion or recirculating-ball system.
• Mechanical linkage connects the steering gear to tie rods/knuckles.
• Normal vehicle front suspension layout.

Concept / Approach:
The steering gearbox receives rotation from the wheel via the shaft and translates it into motion of the rack (in rack-and-pinion) or sector/pitman arm (in recirculating-ball). This motion then moves the tie rods laterally, changing the wheel steer angle through the knuckles.

Step-by-Step Solution:

Verification / Alternative check:
Exploded diagrams show the gear as the conversion element (pinion-to-rack or worm-to-sector).

Why Other Options Are Wrong:

• Steering wheel/shaft are inputs only.
• Tie rods transmit lateral motion but do not perform the initial rotary-to-linear conversion.
• Knuckle pivots about ball joints; it is actuated by the linkage.

Common Pitfalls:
Assuming tie rods “create” lateral motion; they only carry it from the gear to the knuckle.

Final Answer: