Plain English Meaning

Small swinging weights inside the engine that smooth out the twisting pulses caused by the cylinders firing. They are loosely mounted so they can move, which makes them effective at damping vibration but also vulnerable to damage from rough handling of the throttle.

Full Definition

Pendulum-style weights attached to the crankshaft of certain reciprocating aircraft engines that swing on pins rather than being rigidly bolted, allowing them to absorb and dampen the torsional (twisting) vibrations produced by each cylinder firing. Because they pivot freely within designed limits, they can be detuned or damaged by abrupt power changes, sudden throttle movements, or operating the engine outside approved RPM and manifold pressure combinations.

Context Anchor

Encountered in -engine operating guidance, especially when discussing smooth power changes and engine in .