Stop for Maintenance

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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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.


With forty years of brake experience under his belt, Randy Petresh, vice president of technical services for Haldex Brakes, says preventative maintenance (PM) is the one message fleets seem to overlook when it comes to their trucks.

"Maintenance, maintenance, maintenance," he says. "The big thing that concerns me is the fact that maintenance is one of those things often ignored.

"I have 30 or 40 guys that go around training constantly, and every year or two they go back to the same place, same group all over again because everything has changed," Petresh said. The biggest frustration remains that those who ignore maintenance are the same people who complain the most about failed hardware.

With the cost of running a business a constant concern, Petresh understands fleets need to save a few dollars, but in the long run, cutting maintenance may not save them anything. "Everyone is looking for ways to cut corners in maintenance. With fleet operators that run their equipment into the ground, we know they are pushing everything to the wall," he says.

He warns that despite the initial cost of maintenance, fleets can't wait around for components to break. Not only is that practice expensive, but it can also be very dangerous.


From an engineering stand point, Tom Runels, engineering manager for drum brakes at Bendix Spicer Foundation Brake, says trying to predict brake failure and replacement in the medium duty world has become a job in itself, simply because no two duty cycles are ever the same.

"You can have the same brake on a variety of different vehicles, and it will give you a different life based upon the duty cycle, the type of route, whether it is city or rural, and whether it is a mountain area or not," Runels says.

From utility to construction, school buses to delivery, fleets continue to reassess duty cycles and vehicle usage in order to create maintenance and replacement schedules for each and every truck they run. In reference to brakes, there could be a mixed message when relating to maintenance versus replacement.


The issue seems to have become more about knowing when to replace the brakes and less about maintaining the individual components.

Duty cycles are very individual to each fleet, but personalizing maintenance and replacement schedules s a process.

"Most of our customers keep very good records and understand what their requirements are," says Runels. "We try to work with them when we specify materials to be used, whether it's the lining material, brake size and their chamber size, not only to give them the required stopping distance and best life, but we try to help them to time that life to meet their maintenance requirements."

Bendix Spicer Foundation Brake's marketing manager for hydraulic products, Andrew Hess, agrees that efficient schedules measure the level of success for fleets. "The guys who run fleets have a verygood bearing on when they should be looking at things."

Hess points out that fleets keep a careful watch on maintenance and replacement, especially in school bus fleets, because the ability of the brake to function directly relates to the safety of children and the operator.

At the end of the day, component replacement comes back to utilizing the correct PM.

As an engineer, Bendix Spicer Foundation Brake's Runels says, "We try to address (PM) up front when we approve a brake system for a vehicle. We try to size the brake properly, and get the right lining, because if they don't have the right lining or the right brake size, they are going to have maintenance issues.

"As a vehicle gets out into the field, and show signs of excessive wear or fade or some other issue, we would want to get involved to make sure that the person is using an appropriate application. Perhaps there are things we can do to help them reduce the maintenance costs with different linings or a different brake set up," says Runels.


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.

"As we try to specify what brakes should be in the system, it's driven by what the customer says the vehicle will be carrying," says Bendix's Runels. "If they overload them, the symptoms may become excessive wear or overheating-which is certainly a symptom indicating that you will have excessive wear or fade. As far as overloading the vehicle, we would try to specify a brake system that would be within the limits of the vehicle, and hope that the vehicle is used that way."

Regardless of how crisp a fleet's maintenance schedule may be, if trucks are continually being overloaded, the schedules become useless.

"If you are overloading, you are exceeding the design requirements of the components involved," Petresh warns fleet managers. "So, you will have more unplanned or emergency problems because you can't plan normal replacement cycles if you are exceeding the design requirements of the hardware, components will break prematurely, at random, without notice, and significantly increase your downtime, repair costs and equipment utilization."