Definition
A sheet metal forming tool used to bend flat metal stock along a straight line to a specified angle. The metal is clamped between an upper jaw and a lower bed, and a hinged leaf is raised to fold the protruding edge upward to the desired bend angle.
Plain English
A workshop machine that holds a flat piece of sheet metal in place and folds one edge up to make a clean, straight bend.
Context Anchor
Seen in aircraft sheet-metal repair and fabrication when a technician needs to bend a skin patch, bracket, or other thin metal part accurately.
Derivation
The hinged moving part of the machine is called the 'leaf' because it swings open and shut like the leaf of a table. 'Brake' here is an old mechanical term for a tool that bends, breaks, or works material — unrelated to the brakes that stop a vehicle.
Why Pilots Care
Proper function ensures reliable stopping power during taxi, takeoff, and landing; worn leaves can reduce braking effectiveness and increase stopping distance.
Analogy
Think of folding a stiff piece of cardboard along a ruler — you press the ruler down to hold the fold line, then lift the free edge up. A leaf brake does the same thing to sheet metal, with much more force and far greater precision.
Intuition Check
A leaf brake is not a wheel brake, and it has nothing to do with tree leaves. In aircraft maintenance, it is a metal-bending tool with a hinged bending leaf.
Example Sentence 1
The technician used a leaf brake to form a 90-degree flange along the edge of the aluminum patch.
Example Sentence 2
Older aircraft with leaf brakes require different maintenance procedures than modern disc brake systems.