Air disc brakes (ADBs) can offer shorting stopping distances and quicker repair times and, as more customers choose air disc brakes, there are things they can do to maximize the value of the investment.
"The good news is that taking care of ADBs to ensure they reach their full potential is a pretty straightforward matter of knowing some basic facts, paying attention to your brakes and making good choices when it comes to replacement parts," says Keith McComsey, Bendix technical sales lead for wheel-end.
The friction couple
The friction couple — the combination of the brake pad and rotor — converts the vehicle's kinetic energy into heat energy by clamping pads against the rotor and slowing the vehicle down.
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"The contact between the pad and rotor creates friction, generating heat energy that the wheel-end stores and then dissipates," McComsey says. "In fact, one of the reasons ADBs don't experience the brake fade that is seen in drum brakes is that their design manages the heat dissipation differently."
Bendix says rotor metallurgy and pad formulation must be matched intentionally to achieve appropriate torque output and balanced wear.
"When an OE supplier like Bendix can determine exactly what goes into both the rotor and brake pad individually, we're able to engineer them to optimize performance — the actual stopping force provided to slow the vehicle — and wear optimally together," McComsey says. "We can design specific pads to wear at a rate optimally with the rotor. This protects rotor life and helps ensure a quality friction couple. Suppliers that don't design for a friction couple (like some non-OE suppliers) may offer pads that last longer, but wear out the rotor faster."
Choosing the right pad
The correct friction is essential to keep ADBs performing as intended, Bendix says. Fleet type, vehicle configuration and duty cycle all play a role in picking the correct friction material.
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Not all aftermarket pads meet Federal Motor Vehicle Safety Standard (FMVSS) 121, Bendix says, and some aftermarket pads can increase stopping distances versus OEM-specified friction. That's why, the company says, it recommends like-for-like replacements.
Inspections
Even though ADBs don't require lubrication, they still demand attention.
"The key to ADB preventive maintenance is regular inspection of friction wear," McComsey says. "Air disc brakes are lubricated for life and don't need grease fittings or oil spray, so the focus should be on replacing the pads when they near end-of-life, before they could damage the rotor."
Bendix offers a no-disassembly-needed pad and rotor wear gauge to allow technicians to measure thickness on both components and estimate remaining life.
Consider installing ADB pad shields if the vehicle operates in muddy, off-road or debris-prone environments. The pad shields prevent foreign materials from becoming lodged in the brakes and causing damage.
Tools for maintenance
Visual checks are a reliable method for gauging ADB life, but Bendix offers iSense and iSense Pro brake wear sensing systems.
The iSense wear sensing system activates when pads are nearing replacement, sending an alert through telematics to the fleet's home office or technicians can retrieve the signal via diagnostic tools.
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iSense Pro goes further, constantly monitoring both pad and rotor wear at each individual wheel-end as a range of 0-100%, delivering precise messages that report the percentage of life remaining.
"iSense Pro not only identifies specific wheel-ends that require maintenance but provides cross-axle comparison of remaining life," McComsey says. "Seeing the percentage difference between two sides of the axle can help identify potential brake issues and head off costly damage or unexpected downtime. If one end of the axle has 20% or more remaining life than the other, it should alert the technician to investigate."
Air disc performace also impacts advanced driver assistance systems (ADAS), meaning proper maintenance also assures these systems work safely.
