Choosing the Right Brake Lining for Your Truck

The braking system is an essential component of any commercial vehicle. Since it converts kinetic energy into thermal energy, the brake lining material must be strong and withstand high temperatures.
Brake linings produce the friction necessary to stop trucks and machines by pressing against brake drums or rotors. Previously, they were made with asbestos but due to the health risks it presents (such as mesothelioma), manufacturers use tougher brake materials.
Brake Lining Materials
The brake lining is the friction material that converts the vehicle’s kinetic energy into thermal energy to slow it down. It must be able to withstand high temperatures without excessive wear or outgassing (which reduces braking efficiency).
Traditionally, asbestos was used in brake lining because it is inexpensive, easily preformed and has excellent strength, durability and friction properties. However, it has been determined that the inhalation of asbestos fibers over an extended period of time can cause a dangerous lung disease called mesothelioma.
The newest brake lining materials are made of non-asbestos or organic compounds. They are safer to use than traditional brake linings and require less force to stop vehicles. They are also quieter than metal-based brake linings. However, they don’t have the same durability as semi-metallic brake linings.
Stainless Steel
Manufacturers guard the ingredients used in their brake lining with the same sort of zeal that Coca-Cola and KFC protect their secret recipes. Choosing the right lining for your customer's truck requires an understanding of what the GAWR (gamut of axle ratings) is, noise, performance and longevity expectations and the specific driving habits of the vehicle's driver.
Stainless steel is preferred for truck brake applications because of its superior corrosion resistance and strength. This material is particularly helpful for applications like garbage trucks and chemical tankers that carry corrosive materials. It is also ideal for brake components, since it can withstand high temperatures without excessive wear and outgassing. Asbestos was once a popular brake lining material because it is relatively inexpensive, easily preformed and provides excellent wear, durability and friction properties. However, asbestos exposes those making or installing the brake lining to a health hazard. The present brake lining formulation replaces asbestos with vermiculite and other nonfibrous material.
CMP
A preferred truck brake lining is comprised of vermiculite, preferably expanded vermiculite, resin and minor amounts of non-asbestos fibrous material and acicular mineral particles. The mixture is bonded together by a thermosetting resin such as phenol formaldehyde, melamine formaldehyde, urea-formaldehyde, cross-linked alkyd and diallyl phthalate.
When the lining is worn out, an audible warning (typically a squeal) will signal that it is time to replace it. Left unchecked, the squeal will eventually result in drum or rotor damage and degraded braking capacity. These damage events can be costly and may require re-machining or even replacement of the drums or rotors.
Polycarbonate
The brake lining materials used in truck applications include various carbon and synthetic products. These are combined in a specific way to achieve the desired noise, performance and longevity of the product. Each manufacturer guards the formulas of their linings with the same zeal that Coca-Cola and KFC guard the recipes for their beverages.
A disc, block or segment brake lining comprising non-fibrous vermiculite and a thermosetting resin having heat resistant properties, preferably phenol formaldehyde, produces a satisfactory asbestos-free brake lining. The molded brake lining composition has acceptable moldability, shear and flexural strengths and good friction and wear characteristics.
The molded brake linings are injected into a mold and subjected to high pressures for molding. The resulting preform is then cooled down to ambient temperatures.
Brake Lining Replacement Interval
The amount of wear a truck's brake pads receive depends on how many miles the operator drives and where they drive. Full-time commercial drivers putting on a lot of miles in mountainous areas or hot climates will wear their brake pads down faster. Brake pads have a built-in feature that, when the pad lining thickness gets down to 3 mm or less, will trigger a squeal that signals it's time for a new brake job. The first step in replacing your brake pads is to ensure you have a safe way to jack the vehicle up, which typically means two jack stands or a floor jack. You'll also need a set of tools to disassemble and install the new brake liners. These include a wrench and a few plastic disposable cups to contain, separate and mark the components as you take them apart.