Pad wear indicators are a way to quickly check for remaining lining life. For the Bendix ADB22X air disc brake, for example, the greater the distance between the caliper pad wear indicator on the caliper and with the mark on the caliper carrier, the more wearable pad there is.
Photo credit: Photo courtesy of TMD Friction
Once a vehicle’s tires have been analyzed to make sure they are in proper working order, take a quick look at the brakes as well, advise John Thompson, sales manager, OE, NAFTA, and Kenneth Floer, brake field technician, at TMD Friction. While routine preventive maintenance must be part of a good maintenance program, a quick look is always good to make sure there are no glaring issues.
TMD Friction is a leading manufacturer of brake friction materials to the automotive and commercial vehicle industry and has a leading position in the global replacement parts market (www.tmdfriction.us).
Thompson and Floer offer these recommendations for air disc brake systems:
- With the wheels installed, look for rust on the rotors. If an actuator is not working properly, or a caliper is bound-up or seized, the pads will not make contact with the rotor. Eventually, the rotor will rust.
- Look for excessive wear and damage to the rotor. Review the brake manufacturer’s service data for acceptable wear and/or damage.
- If the wheels are off, pad wear indicators are a great way for a quick check of remaining lining life. For the Bendix ADB22X, look at the caliper pad wear indicator on the caliper and see if it aligns with the mark on the caliper carrier.
If they align, the pads are worn out. The greater the distance between them, the more wearable pad there is.
On the Meritor EX225, there is a wear indicator pin that protrudes out of the caliper as the pads wear. When the wear-out mark on the pin is visible, it is time to change the pads.
Look at the top of the caliper where pads are installed. Make sure the two pad springs that locate fore and aft on both pads, are in place and in working order.
With the pad retaining plate in place, the brake pads should not move if there is enough spring pressure. Make sure that the pin holding the brake pad retaining plate is in place and installed properly, and has a retaining spring clip installed.
If there are any questions, refer to the brake manufacturer’s maintenance manual for answers.
The TMD Friction officials further suggest: “A vehicle walkaround, looking for potential issues, should be performed daily. Inspect air hoses for damage. Charge the air system and listen for air leaks.
“Repair any leaks, as even small leaks can cost your fleet money.”