Automotive speed control — role of a governor In an automobile, what is the primary function of a governor mechanism?

Introduction / Context:
Many vehicles use mechanical or electronic governors (speed limiters) to prevent overspeed that can damage the engine or drivetrain, or exceed regulatory limits for certain applications.

Given Data / Assumptions:

• Governor acts on fuel or throttle command.
• Goal is to cap maximum speed rather than finely regulate all speeds.

Concept / Approach:
A governor senses engine or vehicle speed and reduces fuel delivery or throttle opening when a preset limit is reached. This prevents overspeed without attempting to hold a constant rpm at every load, which would be impractical in a road vehicle.

Step-by-Step Solution:

Verification / Alternative check:
Manufacturer data for heavy trucks and some passenger cars list governed top speed or governed engine rpm.

Why Other Options Are Wrong:

• Constant speed under all loads (C): that is a stationary engine governor task, not typical driving.
• Limit power (A) or maximise economy (D): not direct functions; they may be side effects at the limit.
• Tailpipe control (E): handled by aftertreatment and engine management, not a governor.

Common Pitfalls:
Confusing cruise control (maintains set road speed) with a governor (caps maximum speed).

Final Answer: