Regularly taken indicator cards on a slow-speed diesel engine provides relative engine performance data allowing engineers to compare to previous data and manufacturer's design. What are the two most important parameters obtained from reading the indicator cards?
• Indicator cards/diagrams show pressure in the cylinder over the full engine cycle • How Pmax (maximum cylinder pressure) and Pcomp (compression pressure) relate to power, efficiency, and engine condition • Difference between cylinder pressure data and other engine parameters like scavenging air pressure or injection timing
• Ask yourself: Which quantities come directly from the pressure-versus-crank-angle diagram itself, without needing other instruments or gauges? • Which pair of values best let you see changes in engine power output and compression condition over time compared to the maker’s design card? • Which options mix in data that is usually read from separate systems (fuel system timing tools, scavenging air pressure gauges) rather than from the indicator card?
• Make sure you can explain what Pmax represents on an indicator diagram and why it is important for engine loading and power. • Make sure you can explain what Pcomp represents and what it tells you about cylinder condition and compression. • Double-check which listed parameters are truly obtained by analyzing the indicator card shape and pressure levels, not by separate timing checks or air pressure gauges.
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