Automotive speed control — role of a governor In an automobile, what is the primary function of a governor mechanism?
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ALimit the power output at all engine speeds.
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BLimit the vehicle speed (or maximum engine speed) to a safe value.
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CMaintain a perfectly constant engine speed under all load changes.
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DMaximise the fuel economy automatically in every condition.
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EControl exhaust emissions directly at the tailpipe.
Answer
Correct Answer: Limit the vehicle speed (or maximum engine speed) to a safe value.
Explanation
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:
Measure speed via sensor or centrifugal weights.Compare with set limit (calibration).Actuate control (fuel rack, throttle plate, ECU torque request) to reduce power.Maintain speed at or below limit.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:
Limit the vehicle speed (or maximum engine speed) to a safe value.