What term is used for the piston position at the start of a cycle when the piston is at its furthest point before moving?

• A. Top dead center
• B. Bottom dead center
• C. Mid-stroke
• D. Neutral position

Answer: (A)

In piston engines, the piston has two extreme positions where its motion momentarily stops: at the top of the cylinder (top dead center) and at the bottom (bottom dead center). The cycle typically begins when the piston reaches the top dead center, the furthest point upward, where it then starts the compression stroke and the motion begins from rest. This is why the term used for that starting position is top dead center. Bottom dead center is the opposite end of the stroke, mid-stroke is halfway through the travel, and neutral position isn’t used to describe this part of the cycle.