On the indicator card shown in the...

🔍 Key Concepts

• How a diesel engine indicator card shows cylinder pressure versus crank angle over two consecutive cycles • Where on the pressure curve combustion peak normally occurs relative to top dead center (TDC) and bottom dead center (BDC) • The difference between injection events (start/end of fuel injection) and piston position events (TDC/BDC) on timing diagrams

💭 Think About

• Look at where the tall peaks marked by lines A and B occur in relation to the overall compression and expansion shape of the curve—are they tied to combustion pressure or to piston position limits? • Ask yourself whether TDC and BDC would appear once per cycle or could be shown as repeated points on multiple cycles like A and B are here. • Consider whether an indicator card normally marks the exact instant when fuel injection stops, or whether it is more commonly used to relate pressure changes to crank-angle reference points like TDC/BDC.

✅ Before You Answer

• Confirm whether an indicator card is primarily a record of pressure vs. crank angle, not fuel flow vs. time. • Decide if the repeated lines A and B line up with the peak cylinder pressure region that is associated with combustion near TDC. • Verify whether end of injection or end of ignition would typically be drawn with vertical reference lines on a standard engine indicator card, or if those vertical lines usually represent crank positions such as TDC/BDC.

On the indicator card shown in the illustration, what do lines "A" and "B" indicate? Illustration MO-0108

The end of injection

Bottom dead center

The end of ignition

Top dead center

🔍 Key Concepts

💭 Think About

✅ Before You Answer