How is the crankshaft described with respect to throws for each piston?

• A. A shaft with no throws.
• B. A shaft constructed with cranks (throws), one for each piston along its length.
• C. A cylinder block.
• D. A decorative rod.

Answer: (B)

The crankshaft is designed with cranks, or throws, and there is one crankpin (throw) for each piston along the length of the shaft. Each piston’s connecting rod attaches to its own throw, offset from the shaft’s centerline. As the crankshaft rotates, these throws convert the pistons’ up-and-down, reciprocating motion into the shaft’s rotational motion. This arrangement—a crankpin for every cylinder—is what makes a multi-cylinder engine work efficiently. The other options don’t describe the crankshaft’s function: a cylinder block is just the engine housing, and a decorative rod isn’t a component of the engine.