Brake shoes are one of the many mechanical components all braking systems. They carry the brake linings, brake pads, brake blocks, or brake bands, which are connected to them by glue or rivets, to the spinning surface. They do so when they apply pressure to the spinning surface or the brake disc or drum disc of a wheel. This action increases friction and slows the vehicle down. Brake shoes are essential to the smooth operation of vehicles and moving equipment in a number of industries, including agriculture, automotive, cycling, railway, and public transit.
Quick Links to Brake Shoes Information
How Brake Shoes Work
Brake shoes are vital to the proper and safe operation of the braking process. This process begins when a driver or automatic setting presses a lever or pedal, triggering a domino effect of small actions that allow the vehicle to brake safely. First, the brake fluid is released. Under pressure, it travels to every individual braking mechanism, conveying this pressure and amplifying breaking force as a small hydraulic pump engages the shoe. If the brake shoe is working with a drum break, it stretches and thus applies the lining, pad, or block directly onto the spinning surface of the wheel.
At this point, spurred on by the new friction generated between the two materials, the wheel slows down in proportional to the amount of pressure initially applied. On the other hand, if the brake shoe is working in conjunction with a disc brake, the lining, pad, or block onto which it extends does not make contact directly with the wheel, but rather a disc that is connected to the wheel. This process generates a large amount of heat and, for this reason, brake shoes must still be able to hit their mark even when thermal expansion is factored in. In addition, they must be able to apply an extreme amount of pressure onto the wheel or disc when engaged, all the while staying completely clear of the wheel or disc when disengaged.
Brake Shoe Design Design and Customization
Because brake shoes are used for such a vast number of applications, they are available in many different sizes and material configurations. The first component of the brake shoe is block or plate, usually made of metal or ceramics. Curved to be compatible with the wheel or disc, the plate is typically made of iron, steel, or copper. Also acceptable are any alloys that have sufficient heat resistance and durability characteristics.
The use of ceramic brake shoe components has grown in more popular and prominent in the last several years. It continues to grow, as ceramic components are high durable, have excellent absorption qualities, and are much quieter than their metal counterparts. Metal brake shoes, by contrast, let out an irritating grinding noise when they become worn.
Whether the plate component is made of metal or ceramic, it is connected to the pad or lining by rivets or advanced adhesives. Linings may be made from any number of different of rough or textured materials, known as friction materials, to slow or decrease friction-causing movement. Some of common materials selected to make suitable mixtures include mineral fibers, chopped glass, cellulose, copper fibers, aramid fibers, steel fibers, ceramics, and other carbon composites and semi-metallic and non-metallic materials. Many years ago, the most popular friction material was asbestos fiber, but that is no longer the case, as we now understand that prolonged exposure to asbestos can cause many serious health problems, including the development of mesothelioma, lung cancer, and a type of pneumoconiosis called asbestosis.
Materials Used in Brake Shoe Applications
The selection of brake shoe materials is on a few different considerations. These include, first, wear rates and performance and, second, brake fluid compatibility. Most brake fluids today are glycol-ether based, but other types, including castor oil-based and silicone-based, are available for purchase and use. All brake fluids must meet various requirements of the state and federal government. All brake fluids sold in the North America, for example, must meet the United States Department of Transportation (DOT) standards. Another set of standards to which most brake fluid manufacturers are beholden are those set out by SAE International (Society of Automotive Engineers International).
Brake Shoe Maintenance Considerations
The health of brake shoes must be diligently maintained. Over time, brake shoes become worn, and if they are allowed to wear for too long, the shoe can become directly exposed to the spinning surface. While this may not seem like a big problem, as it still allows for vehicle-slowing friction, it in fact can cause major damage to the surfaces of both the shoe and the wheel or disc. Fortunately, advances in material and chemical engineering, as well as brake shoe design, are helping brake shoes last longer and function better. However, it is still important to treat your brake shoes and your whole braking system well. You may also purchase brake testers, which allow you to know if your brakes are in an acceptable condition. For more information, contact a brake manufacturer today.