Steam Engine Governing Methods — Throttle vs Other Types When engine speed is controlled by a valve in the main steam pipe that regulates the pressure of steam entering the cylinder, the method is called:

Introduction / Context:
Governing maintains engine speed under varying load. Several methods are used in steam practice, notably throttle governing, cut-off governing, and by-pass governing. The question asks you to identify the method that works by directly throttling inlet steam pressure before admission.

Given Data / Assumptions:

• Main steam valve located upstream of the admission port.
• Governor adjusts valve opening with speed error.
• Goal is speed control, not necessarily maximum efficiency at part load.

Concept / Approach:
Throttle governing reduces the inlet pressure by partially closing a throttling valve, lowering admission pressure and thus power output. In cut-off governing, the governor changes the fraction of the stroke at which admission ceases, keeping inlet pressure high but shortening admission duration. By-pass governing diverts a portion of steam away to control the mass flow. Since regulation here is via a main valve reducing pressure, the correct term is throttle governing.

Step-by-Step Solution:
Identify the manipulated variable: inlet pressure via throttle position.Map method to name: throttling → throttle governing.Reject alternatives that alter cut-off timing or by-pass flow.

Verification / Alternative check:
Indicator diagrams at part load show reduced initial pressure under throttle governing, confirming the method.

Why Other Options Are Wrong:
cut-off governing: varies cut-off, not inlet pressure.by-pass governing: diverts steam around the cylinder rather than throttling it.none of these: incorrect because throttle governing fits the description.

Common Pitfalls:
Thinking that throttling always yields best efficiency; cut-off governing is often superior in that respect.

Final Answer:
throttle governing