Definition
A one-way V-shaped seal used on hydraulic and pneumatic components to prevent fluid leakage past a moving part such as a piston rod or actuator shaft. The seal is installed so the open side of the V faces the pressure, allowing system pressure to spread the lips of the V outward against the mating surfaces and tighten the seal as pressure increases.
Plain English
A rubber seal shaped like the letter V that keeps hydraulic fluid from leaking past a moving rod. The harder the fluid pushes on it, the tighter it seals.
Context Anchor
Seen in aircraft maintenance when working on hydraulic actuators, landing gear components, brakes, and other parts where pressurized fluid or air must be sealed around a moving piece.
Derivation
Named for its shape. A chevron is a V-shaped or inverted-V design, a term borrowed from heraldry (where it appears on shields and military rank insignia) and originally from the Old French chevron, meaning 'rafter' — because two rafters meeting at a roof peak form the same V shape. The seal earns its name from that same V profile.
Why Pilots Care
Maintains hydraulic pressure integrity needed for flight controls and landing gear.
Intuition Check
Chevron does not mean a rank badge or road marking here. In this maintenance term, it refers to the V shape of the seal, and that shape is what helps it seal under pressure.
Example Sentence 1
During the actuator overhaul, the technician replaced the worn chevron seals to stop the slow hydraulic leak past the piston rod.
Example Sentence 2
Chevron seals are commonly used in high-pressure fuel pumps because the V shape improves sealing as pressure rises.