A growing number of fleets are adopting air disc brakes (ADBs). In fact, some forecasts show 30 percent of the North American market will be specifying ADBs by 2020, compared to 10 percent in 2010.
Fleets have experienced reduced stopping distances with ADBs, providing payback in the form of fewer accidents.
Plus, ADBs providing substantial savings in time and labor when it comes to maintenance and repair. However, any new technology comes with a learning curve, and ADBs are no exception.
It is important for technicians to know how to inspect and maintain ADBs, not only to protect the equipment but to ensure the fleet experiences the full benefit of their investment. It is a case where a little training pays off in a big way.
Inspection routines to consider
Fleets can start by implementing an inspection routine that includes intermittent wheels-on inspections as well as more comprehensive (but less frequent) wheels-off inspections to keep their calipers in working order.
Wheels-on inspection for ADBs
The technician can take a quick look at each brake for pad wear and rotor condition, followed by an adjustment test. Further, the caliper can be inspected for any loose or missing caps, plugs, and mounting bolts.
This type of inspection should be done during the fleet's or manufacturer’s chassis lubrication schedule or at least four times between pad changes – whichever is most frequent.
Wheels-off inspection for ADBs
This is a more thorough inspection that allows the technician to check the slide pin, tappet boots, and pad abutments. The technician can then check for caliper free play, which is an indicator of bushing or slide pin wear. This should be done during a wheel service or tire replacement.
While this may sound complicated, ADBs are easier to service than drum brakes because they are built with fewer components. Reduced labor costs and increased vehicle uptime represent enormous potential benefits to fleets.
Manufacturers of ADBs are the best sources of maintenance and service information on their systems.
Comparing maintenance by brake type
Drum brake maintenance often involves inspecting brake linings and lubricating cam bushing and slack adjusters, while servicing ADBs often requires only checking for pad wear as well as making sure the boots and seals are in good condition. Consider the following comparison of changing brake pads on the two systems.
Installing new pads on a drum brake is a 10-step procedure:
- Remove wheel
- De-adjust slack adjuster
- Remove drum
- Pull off retainer springs
- Remove old brake pads
- Install new brake pad shoes, anchor pins, and springs
- Lubricate S-cam and automatic slack adjuster
- Measure applied stroke
- Reinstall drum
- Reinstall wheel
Total time: 90 minutes
Installing new pads for an ADB system involves the following:
- Remove wheel
- Remove pad retainer strap
- Remove old brake pads
- Back off caliper piston
- Inspect boots, pad abutments, and caliper free play
- Install new brake pad
- Reinstall pad retainer strap
- Set running clearance
- Reinstall wheel
Total time: 30 minutes
The time saved is multiplied by the number of wheels to be serviced, meaning the time savings can be significant.
As service managers and technicians become more familiar with ADBs and the best practices for service and maintenance, fleets continue to experience the benefits and accelerate adoption.
Justin McCoy is the Meritor aftermarket senior product manager for disc brakes. He has 30 years of experience in the trucking industry. He started in the heavy duty aftermarket industry working for a western Canadian warehouse distributor. He holds an undergraduate degree in Economics and a Master of Business Administration. Headquartered in Troy, Michigan, Meritor is a global supplier of drivetrain, mobility, braking, and aftermarket solutions for commercial vehicles.
