Just as it requires force to send an object into motion, force is required to halt an object in motion. This force can come in many different forms — sometimes it is gravity, friction, or the force exerted by a concrete wall.

While there are many ways to stop a moving object, in industrial settings with many durable goods one of the most common ways involves using a braking system. Braking systems come in many shapes and sizes, but two of the most popular types are mechanical and non-contact.

Mechanical braking system

A mechanical braking system is likely the most recognized due to their abundance in consumer goods like bicycles and cars, which both feature mechanical braking systems. Mechanical braking systems provide friction force to a moving object. The friction force, depending on the size of the force and the duration applied, eventually overcome the kinetic energy of the moving object and bring it to a stop. As the brake is applied, the mechanical energy of the moving object dissipates in the form of heat, sound and light.

There are two subcategories under mechanical braking systems: shoe-style and pad-style braking systems. Shoe-style and pad-style braking systems are both abundant in braking systems and are appropriate for many applications.

A shoe-style braking system stops motion by moving a shoe, a metal object that is lined on its surface with brake-friendly material known as a shoe lining, against the inside of a drum or against the outside of some other type of rotating object. This creates a friction force that brings the motion to a halt.

A pad-style braking system is a mechanical braking system that stops motion by applying brake pads to the outside face of a moving object. When pad-style braking systems are used on a rotating circular object, they are called disc brakes. Like shoe-style brakes, the friction force brings the moving object to a stop.

Non-contact braking system

A non-contact braking system stops an object in motion without using friction. An example of this is the eddy current non-contact braking system, which uses electromagnetics and eddy currents to stop objects in motion. While eddy currents can be complex, at a fundamental level they are electromagnetic forces that are generated when a conductive object passes through an electromagnetic field.

The conductive object in an eddy current braking system for a wheel is typically a metal rotor. In a non-contact eddy current braking system, the opposing forces of the electromagnetic field and the eddy currents are what terminate the motion of the moving object. Non-contact eddy current braking systems are sometimes preferred over mechanical brakes because their contactless nature means that no wear occurs, resulting in less frequent maintenance.

Figure 2: Non-contact brakes use eddy currents to halt motion.Figure 2: Non-contact brakes use eddy currents to halt motion.

Applications for mechanical brake systems

Contact brake systems are used for many different applications, the most common of which are automobiles. When the brake pedal in a car or truck is pressed, hydraulic forces push the pads of a disc brake or the shoes of a disc brake against some component attached to the rotating axles to stop the automobile. Other similar applications for mechanical brake systems include bicycles and industrial machinery.

Applications for non-contact brake systems

Eddy current braking systems are used when high speed objects would cause so much wear that it would not be feasible to use mechanical brakes. They are also used when low maintenance is a key requirement. Examples of non-contact eddy current braking systems used in the world include high-speed trains and various types of industrial machinery.

Repair considerations

Braking systems can deteriorate over time and may need to be repaired and mechanical brake systems generally require the most repairs. The most common repair needed for mechanical brakes is brake lining replacement either on the brake pad or the brake shoe, depending on the type of non-contact brake system in use.

Another common repair is usually performed on the rotor if it becomes gouged or warped. While they are sometimes machined to make them flat and true again, it is more common for them to be replaced altogether. Other repairs include fixing broken hydraulic brake lines that supply the force to the pads or shoes and caliper replacement. Non-contact brake systems generally require less repair than mechanical brakes, but sometimes the electromagnetic equipment may need replacement. If the rotor undergoes excessive heat during the eddy current braking process, it may become warped and require replacement.