Steam engines: effect of wire drawing (throttling during valve events) on the indicator diagram and work done Assess whether throttling (wire drawing) reduces the diagram area and thus the indicated work of the engine. State whether the statement is true or false.

Given statementWire drawing (throttling through ports/valves) decreases the area of the indicator diagram and hence reduces work per cycle.

ConceptWire drawing lowers the mean effective pressure (MEP) during admission/exhaust due to throttling losses; reduced MEP directly reduces the area enclosed by the pressure-volume (P–V) indicator diagram.

Step-by-step logic• Losses at admission/exhaust → reduced pressure trace.• Reduced P–V area → lower indicated work per cycle.

Final AnswerTrue — area decreases and indicated work reduces