Emergency brake can refer to:

Cars and motor vehicles

• Braking during an emergency.

• Autonomous emergency braking (AEB) in a collision avoidance system, which engages the main braking system in automobiles when a computer detects an imminent collision
• Advanced emergency braking system, where brakes are applied automatically in case of emergency
• Emergency brake assist (EBA or BA), which increases braking effectiveness when a human driver executes a panic stop
• Parking brake or hand brake in automobiles, which can also be used in case of failure of the main braking system

Planes

• Autobrake, a system for automating braking during takeoff and landing of airplanes

Trains

Wikimedia Commons has media related to Emergency brakes.

• Emergency brake (train), a term which can refer to a stronger-than-normal braking level, a separate backup braking system, or the lever used to engage the backup braking system
• Train protection system, which engages an emergency brake in dangerous situations