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Eddy Current Brakes

Linear Eddy Brake Assembly		Linear Eddy Brakes at Walibi Holland (Netherlands)

 

 

Magnetic Eddy Brakes, also known as eddy current brakes, operate on the principle of electromagnetic induction.
Here are the concepts and brief explanation of how they work:

Physics principles involved in Magnetic Eddy Current Brakes

1. Magnetic Field Creation: Eddy current brakes generally consist of a conductive metal plate and stationary magnets. Alternatively, the conductive metal could be stationary while the magnets are in motion. Copper and Aluminum are the most common conductive metals used in Eddy current brake systems.
2. Relative Motion: When the conductive metal moves relative to the magnetic field, it passes through the magnetic field lines. This relative motion between the conductive metal and the magnetic field is essential for generating eddy currents.
3. Induction of Eddy Currents: According to Faraday's Law of Electromagnetic Induction, a changing magnetic field induces an electric current in a conductor. As the conductive metal moves through the magnetic field, circular currents, called eddy currents, are induced within the metal.
4. Opposing Magnetic Field: These eddy currents create their own magnetic field, which opposes the original magnetic field (as per Lenz's Law). This opposition generates a resistive force that acts against the motion conductive plate.
5. Dissipation of Energy: The resistive force generated by the eddy currents converts the kinetic energy of the moving disc into thermal energy (heat). This process slows down the motion of the conductive metal, effectively braking or slowing it.
6. Controllability: The braking force can be controlled by adjusting the strength of the magnetic field (size of the magnet, or proximity to the conductive metal) or by changing the speed of the conductive metal. Stronger magnetic fields and higher speeds generate more significant eddy currents and, consequently, stronger braking forces.

Applications

• Transportation: Eddy current brakes are used in high-speed trains, roller coasters, and other amusement rides.
• Industrial Machinery: They are employed in various industrial applications where precise and controlled braking is necessary.
• Testing and Measurement: Eddy current brakes are used in dynamometers to test engines and other machinery.

Limitations

• Heat Generation: The conversion of kinetic energy into heat can cause significant heating of the conductive metal, which may require cooling mechanisms to prevent overheating the magnets or the conductive metal.
• Effectiveness at Low Speeds: Eddy current brakes are less effective at low speeds because the induced eddy currents are weaker when the relative motion between the disc and the magnetic field is slower.

Properties of Eddy Brakes vs Friction Brakes

Properties		Eddy Current Brakes		Friction Brakes
No Physical Contact		Operate without any physical contact between the braking components, leading to minimal wear and tear.		Involve physical contact between brake pads and rotors or drums, which leads to wear and tear and requires frequent maintenance and replacement.
Maintenance and Longevity		Have fewer moving parts and no contact surfaces that wear out, resulting in lower maintenance costs and longer service life.		Require regular maintenance to replace worn-out brake pads, rotors, or drums, increasing downtime and operational costs.
Smooth and Consistent Braking		Provide smooth and consistent braking force without the risk of jerky movements, enhancing safety and comfort.		Can sometimes cause jerky braking, especially if the brake pads or rotors are unevenly worn or if there is contamination on the braking surfaces.
Silent Operation		Operate silently because there is no physical contact or friction between moving parts.		Can produce noise due to the friction between brake pads and rotors, especially when the components are worn or contaminated.
Temperature Management		While they do generate heat due to the conversion of kinetic energy into thermal energy, they do not suffer from the same fade issues as friction brakes because the heat is not concentrated at a single point.		Can experience brake fade during prolonged or heavy braking due to the buildup of heat at the contact surfaces, reducing braking effectiveness.
Reliability in Harsh Conditions		Are less affected by environmental conditions such as water, mud, or dust because they do not rely on friction surfaces.		Can be less effective in wet or dirty conditions as water, mud, or dust can reduce the friction between the brake pads and rotors.
Efficiency at High Speeds		Are particularly effective at high speeds, making them suitable for high-speed trains, roller coasters, and other high-speed applications.		Can suffer from reduced efficiency at very high speeds due to the limitations of friction material and the risk of overheating.
Less prone to Failure		Are always on, can’t be turned off, and don’t rely on external power. Some systems require the Eddy brakes to be actuated, and the actuator system may have points of failure.		Systems use springs, pneumatics or electricity to actuate. All of these have failure points due to their reliance on other systems. Due to this fact a backup braking system is almost always utilized.

 

Amazing Magnets has an inventory of magnets used in the creation of Eddy Current Brakes and Braking Systems.
If you have a need for Eddy Current Brakes in your application or attraction, please email us at customercare@amazingmagnets.com to start a conversation.