🔍 Key Concepts

• Four-stroke diesel engine timing and the normal speed relationship between the crankshaft and camshaft • How gear ratios between meshing gears determine relative rotational speeds • Which shaft in a four-stroke engine must complete one revolution vs. two revolutions for a full engine cycle

💭 Think About

• Look at where label "B" is located in the gear train: is it attached to the crankshaft or to the camshaft? • For a four-stroke cycle, how many turns does the crankshaft make for each full cycle of valve operation controlled by the camshaft? • If two gears of different sizes mesh, which one turns faster, the smaller or the larger, and how does that relate to crankshaft vs. camshaft speed?

✅ Before You Answer

• Verify whether B is physically drawn on the crankshaft gear or on the camshaft gear in the illustration • Confirm the basic rule: in a four-stroke engine, the crankshaft must rotate how many times for each camshaft revolution? • Check that your choice’s wording matches both the component at B and the correct speed ratio between crankshaft and camshaft