Definition
An endless power-transmission belt with a trapezoidal (V-shaped) cross-section that runs in matching V-shaped grooves on pulleys. The wedging action of the belt sides against the groove walls produces high friction, allowing significant power to be transmitted without slipping.
Plain English
A rubber drive belt shaped like a V in cross-section. It wedges into matching grooves on pulleys, gripping firmly so it can turn one shaft from another without slipping.
Context Anchor
Seen during engine inspection, maintenance, and preflight checks around engine-driven accessories.
Derivation
Named for its cross-sectional shape, which resembles the letter V. The V-shape is the functional point of the name: it is what lets the belt wedge into the pulley groove and grip tightly.
Why Pilots Care
A failed or loose V-belt can cause loss of electrical charging or vacuum-powered instruments, forcing an immediate diversion or precautionary landing.
Intuition Check
Do not read “V” as a model name or speed rating. In V-belt, it describes the belt’s shape when viewed from the end.
Example Sentence 1
During preflight, the pilot checked the alternator V-belt for proper tension and signs of cracking or fraying.
Example Sentence 2
A slipping V-belt caused the vacuum pump to slow, making the attitude indicator unreliable.