Governing of steam engines — speed regulation under load changes State whether the function of a governor in a steam engine is to keep the engine speed approximately constant as the load varies.

Introduction:
Governing is essential for prime movers to maintain nearly constant speed when load fluctuates. In steam engines, a governor automatically adjusts steam admission so that the mean speed remains within acceptable limits despite changing torque demand from the driven machinery.

Given Data / Assumptions:

• Conventional centrifugal or mechanical governor linked to the throttle or cut-off mechanism.
• Reasonably steady boiler pressure and adequate steam supply.
• Normal operating regime, not emergency trips.

Concept / Approach:
A governor senses speed (or speed error) and modulates energy input. In a steam engine, this is commonly achieved by changing valve cut-off or throttle position. Increased load tends to slow the engine; the governor responds by admitting more steam; decreased load tends to accelerate the engine; the governor restricts steam admission. The goal is speed regulation, not exact constancy, as there is always some droop for stability.

Step-by-Step Solution:

Verification / Alternative check:
Speed-time plots for governed engines show small deviations and corrections instead of runaway acceleration or stalling. The same principle underlies governors in turbines and internal combustion engines.

Why Other Options Are Wrong:

• No / startup-only: contradicts the continuous control role.
• Only at constant steam pressure: a governor compensates for load changes even if steam pressure varies slightly; boiler controls handle pressure regulation.
• Applies only to hydraulic turbines: governing is a cross-technology concept.

Common Pitfalls:
Confusing governor action (speed control) with flywheel action (energy storage for cyclic speed smoothing); expecting zero droop, which can cause instability.

Final Answer: