Stop for Maintenance

Medium duty vocational brakes are unquestionably a heavy wear item, but can proper maintenance practices help extend component life?

From maintenance to replacement, high service items like brakes have slowly become the itch fleets can't reach as technology and duty cycles continue to increase equipment down time. WEIGHING THE COST With forty years of brake experience under his belt, Randy Petresh, vice president of...

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Runels encourages customers to refer back to the OEMs for recommendations to assist them in choosing components that will best suit the work application.

Haldex's Petresh also encourages fleets to look to consultants and organizations to provide insight into creating maintenance and replacement schedules.

"Organizations like the Technology and Maintenance Council (TMC) will provide recommended practices and procedures and maintenance advice directly through the organization and indirectly through those who attend TMC sessions," Petresh says.

TMC's Recommended Maintenance Practices provides information on RP 1407 "Hydraulic Brake Maintenance Guidelines" and many other areas of brake repair.

Petresh points out that there are a consultants who will contract for weeks or months to come into a fleet and help them. Regardless of which technique a fleet chooses, all of the experts will say you have to tailor the PM cycles, practice and procedures based upon the application.

"How you use the equipment, where you are, what you do with it, etc' The best practice is to develop and fine tune the PM practices based on the fleet's operation," says Petresh.


There are some things a fleet can do to combat the environment and climate. Maintenance symptoms and practices will be different depending upon which part of the country the fleet is operating from to what type of brake the fleet uses on their trucks.

According to Petresh, hydraulic brakes are probably the best option for normal applications and usage. However, he goes on to say, "If you get into the specific niches or vocational markets, that's where the tendency is to use more air brakes because they are structurally more robust. They are designed and built for heavier applications and more severe usage and duty cycles," he says.

Chuck Eberling, a principal engineer in vehicle systems group for Bendix Commercial Vehicle Systems, states that when it comes to air brakes, climate conditions and the size of the truck are all issues to be considered when choosing the correct components.

"A big concern, if it is a vocational vehicle that uses a lot of air, obviously is the capacity of the compressor, and the ability of the air dryer to treat that amount of air consumed," he says.

"The maintenance of those items in respect to making certain the system is dry, becomes an issue particularly in the cold weather months. We are taking atmospheric pressure and compressing it up to eight times, which means we are going to produce raw water as a byproduct of that process. We need to have a dessicant type air dryer to remove moisture, and that air dryer needs to be in good operating condition particularly in these months," Eberling continues. "It's more obvious in the cold climates where moisture in the system can result in potentially a freeze-up of the vehicle air system, thus the vehicle becomes stranded.

"In the warmer climates, it would lead to deterioration of the vehicle's air system performance as a result of the moisture in the system which does tend to shorten component life by removing lubricant from the system components," says Eberling.


When considering brake usage in vocational trucks, construction, refuse, transit and delivery are a few vocations where there is a constant start-and-stop effect, the brakes are going to cause more brake wear.

Runels says, "It's the frequency of stops that causes heat to build up, and of course the outcome of that is potential excessive wearing of linings or fade in brakes. Maintenance then becomes focused on wear."

Overheating can be caused by more than just starting and stopping. Overloading a vehicle is not only hard on the suspension, tires and shocks, but the brakes feel the damaging effects as well.

When spec'ing the appropriate brake for a certain application, companies like Bendix and Haldex can only trust that the customer is utilizing the components to their specifications.

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