Maintenance for brakes is, obviously, crucial—the brakes are what stops the truck, after all. More fleets are spec’ing air disc brakes, but as these brakes are new to a lot of fleets, they may not be aware of what needs to be looked at when it comes to preventative maintenance. Here’s what several brake experts had to say.
“When it comes to any brake system, they all require preventative maintenance, not only to keep them operating effectively in providing continuous brake performance, but also to provide long life to the components,” says Keith McComsey, director of marketing and customer solutions for Bendix Spicer Foundation Brake LLC. “Air disc brakes are no different. Your ADB system should be routinely checked for a number of things:
- Inspect pad friction thickness to ensure it has not fallen below the minimum; verify even pad wear, not only across the pad but also comparing the inboard vs. outboard pad; and make sure that friction is not cracked.
- Inspection of the rotor is also important. Verify that rotor thickness is greater than the minimum, and also verify that there are no stress cracks in the rotor. If there are stress cracks, check them against acceptable levels.
- Boot inspection can be important as well. Make sure that your boots are in good working order and do not exhibit any tearing of the boot material that would allow moisture and contaminants into the caliper.
- Verify that the caliper can slide freely.”
“For disc brakes, it is important to pay close attention to brake pad wear,” says Marty Watterson, Meritor’s field service manager for the trailer division. “Our Meritor EX+ air disc brakes make this easy via our visible wear indicator mechanism, which can provide an effective visual indication of pad wear without removing the wheel. Also, ensure all boots and seals are in good condition to provide the absence of contaminants.”
“For drum brakes, make sure brake linings are operating at the legal thickness limit, or they should be changed,” he continues. “If changing the brake linings, also inspect the cam bushings and change them if needed. Be sure to regularly lubricate cam bushings and slack adjustors. Brake drums should be measured to assure they have not reached wear limit. When replacing, make sure to always use factory service parts. As always, refer to the manufacturer’s maintenance manuals for proper procedures.”
“A comprehensive preventative maintenance program includes two critical components: maintaining good records and understanding your operating conditions,” says Jeff Wittlinger, business unit director of wheel-end and brake systems for Hendrickson. “Dynamics like average length of haul, application, terrain, driver patterns and tractor-trailer equipment combinations are important factors to consider when determining intervals at which components like brake linings should be replaced. Some specific recommendations include:
- Train drivers on what to look for during their daily “walk around” inspections. For instance, look for signs of oil around the hub and wheel and ensure hoses are not touching wheels or brake equipment.
- Establish a regular maintenance schedule for drum or disc brakes. This includes checking lining / pad thickness and measuring brake stroke for drum brakes.
- If brakes are out of adjustment, diagnose the root cause for the issue and assess an appropriate course of action. Don’t assume that simply manually adjusting the brake will solve the issue.”
“Listen to the driver and inspect all safety systems often,” advises Jeff Geist, director of engineering with Stemco Brake Products. “Drivers are responsible for operating a safe vehicle which means reporting possible braking issues, changes or concerns with their maintenance provider. If the driver has any anxiety about pulling over for a roadside check, then there is likely an issue present. Where possible, check brake stroke often as it can be an early warning of possible brake system faults developing, or a dangerous situation present. Stemco Crewson brake adjusters have a large easy to view stroke indicator that makes inspecting the brake operation a very easy and safe task without going underneath the vehicle.”