Definition
A type of aircraft wheel brake that uses a synthetic rubber tube wrapped around the brake hub. When hydraulic pressure is applied, the tube expands outward and pushes a series of brake blocks against the inside of the rotating brake drum, creating friction that slows the wheel. When pressure is released, the natural elasticity of the tube retracts the blocks away from the drum.
Plain English
An older style of wheel brake where a rubber tube swells up with fluid pressure and pushes friction blocks against a spinning drum to slow the wheel. Releasing the pressure lets the rubber tube shrink back and free the wheel.
Context Anchor
Seen in aircraft brake system descriptions and maintenance procedures, especially on older drum-style aircraft wheel brakes.
Derivation
Named for how it works: an expander tube is a rubber tube that expands when filled with fluid. The name describes the action — fluid pressure expands the tube, which applies the brake.
Why Pilots Care
A leak, damaged tube, or worn friction material can reduce braking and may cause poor stopping action or uneven braking during taxi, landing rollout, or parking.
Analogy
Think of a bicycle inner tube wrapped around a hub. Pump fluid into it and it swells outward, pressing pads against the inside of a metal ring around it. Release the fluid and it shrinks back.
Intuition Check
Do not picture this tube as just a hose that carries fluid. In this brake, the tube is the part that swells and applies the braking force.
Example Sentence 1
The mechanic inspected the expander-tube brake for cracks in the rubber tube before returning the aircraft to service.
Example Sentence 2
Older light aircraft often use expander-tube brakes instead of modern disk systems.