Mercer Transportation


How to Measure and Improve Your Truck Brake Maintenance Program

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It may be tempting to base PM intervals on historic brake life data, but corrosion, rust-jacking, and even poor-quality offshore products have shortened the life expectancy of many brake products.

How do you gauge the effectiveness of your brake maintenance program? It’s a tricky question because there are so many factors to consider.

Cost is certainly a factor. Excessive equipment downtime might be another, as well as federal CSA safety scores. And is your maintenance program good enough that drivers can absolutely depend on their brakes when some urgent need arises?

Several directives come into play with brake maintenance.

Obviously, you want to stay on the right side of the roadside inspectors. The five-year average for brake-related out-of-service rate during the Commercial Vehicle Safety Alliance’s Brake Safety Week (2016-2021) is 13.2% of the trucks inspected. Those defects included having 20% or more of the brakes on the truck stroking beyond their adjustment limit, contaminated brake linings, badly chafed or damaged brake hoses, or missing or broken brake parts.

Would you be satisfied if only 86.8% of your fleet passed an in-house brake audit akin to a CVSA Level 1? Would that be a satisfactory measure of your fleet’s brake maintenance program? Could you look your shareholders, executives, or plaintiffs’ lawyers in the eye and convince them everything’s fine because you’re ahead of the curve on brake maintenance?

The Importance of Truck Brake Inspections

Using CVSA level 1 inspection results as a benchmark for your own brake maintenance program would be a good place to start, but that’s not the be-all and end-all.

CVSA inspectors search for violations, and they know exactly where to look. The organization publishes an Out-of-Service Criteria guide book every year. It lists all the possible out-of-service conditions, but not necessarily all possible brake violations. If your techs were trained in conducting Level 1 brake inspections, they would probably spot the defects before the inspectors did.

That might help with your CSA Maintenance BASIC scores, but it won’t help with detecting performance deficiencies, such as glazed brake linings, out-of-round or non-concentrically mounted brake drums, brake balance, or application and release timing.

An inexpensive drum gauge easily provides visual a go/no-go determination of brake drum integrity.

Looking for Clues in Brake Inspection Out-of-Service Numbers

If you’re looking for a place to start, check out the top three violation categories from any recent CVSA inspection blitz. For example, an unannounced blitz last year revealed the following top three brake-related out-of-service conditions:

  • 20% Brakes Violations – 479. A vehicle or combination of vehicles is declared out of service when 20% or more of its service brakes have an out-of-service condition resulting in a defective brake, such as a brake out of adjustment, an audible air leak at the chamber, defective linings/pads, or a missing brake where brakes are required.
  • Other Brake Violations – 368. Examples of other out-of-service brake violations are worn brake lines, broken brake drums, inoperative tractor protection system, inoperative low air warning device, air leaks, or hydraulic fluid leaks.
  • Steering Brake Violations – 81. Examples of automatic standalone out-of-service steering axle brake violations include inoperative brakes, mismatched brake chambers, mismatched slack adjuster length, and defective linings.

“Run your CSA scores for equipment and maintenance violations and compare your company’s scores to those of your competitors,” recommends maintenance consultant Bruce Stockton of Stockton Solutions. “That is all public information, and all fleets are graded the same by roadside inspections. Pull out those where brakes were the violation and see where you stand.”

Stockton says below-average numbers mean you should start conducting your own inspections and the necessary corrective action.

“Don’t wait to be inspected. Inspect it yourself, identify corrections needed. Take a proactive approach.”

CVSA usually makes its inspection targets known well ahead of the actual event. For the past couple of years, CVSA inspectors have targeted brake hose and air system defects.

Those initiatives are not randomly selected.  

Will Schaefer, former director of safety programs at CVSA, says a committee meets twice a year to review the results of past inspection campaigns, looking at the top violation categories. They identify the most prevalent violations from previous years and launch a focused inspection campaign.

“Recently, we’ve been looking closely at brake hoses,” he told HDT.

Maybe brake hoses are something you ought to get your technicians and drivers to inspect more carefully — or whatever else CVSA has identified as problematic.

Drivers Are Part of the Maintenance Program

Since drivers occupy a front-line position with respect to brakes, their input on brake condition and function can be invaluable — providing they are offering accurate and timely information.

The required driver vehicle inspection report is one way of communicating concerns, and even genuine problems. But fleets could go beyond that and add more general queries to trip reports, such as whether drivers had noticed anything unusual about the brakes — not necessarily a specific prescribed defect.

“If you gave drivers the same sort of training on vehicle inspections that our inspectors get, I’m sure they’d be able to spot all the violations that our inspectors do,” Schaefer says.

If drivers did their pre-trip inspections armed with that kind of training, they would notice the telltale signs of brakes being out of adjustment, or brakes not applying, like seeing old rust on the inside surface of a brake drum or a brake rotor.

“In other cases, I think they’re not even looking,” Schaefer says. “I think that some pre-trip inspections might be, let’s say, a little cursory.”

That’s a problem, too. But there are cases where drivers complain about, say, the truck being hard to stop or the brakes not feeling right. They won’t know why, but they trust the mechanics to sort it out. If nothing obvious is found during an inspection, the shop will put the truck back out and the driver will complain again.

After a couple of such go-arounds, somebody will finally decide to have a close look at the brakes, and lo and behold, they find a problem like glazed brake linings or seized clevis pins — both of which will reduce the brake force between the lining and the brake drum.

In Stockton’s experience, not all drivers are well versed in mechanical issues involving brakes, but if they are complaining about something, it should be investigated. And he cautions, fleets need to be more proactive generally than just hoping drivers will complain about a problem.

“Never assume drivers are going to report a problem,” he stresses.  

Even with almost one half inch of lining left, this school bus brake is finished thanks to rust-jacking.

When it Comes to Stopping a Big Rig, 1 Foot Can Be a Big Deal

Neither of these hypothetical problems will be obvious with a cursory visual inspection. All the parts would be moving as they should be. The angle between the slack adjuster and the push rod might be correct, but the stopping force is compromised by an unseen problem.

“I did some testing on glazed brake linings a number of years ago,” says Darry Stuart, president of DWS Fleet Management Services, a fleet maintenance consulting firm based in Wrentham, Massachusetts. “We found the difference in stopping distance between a glazed brake shoe and a new brake shoe is about 10 feet. Not much when you think about it, and I told a driver that, once. He told me one foot can be a big deal when you’re hauling gasoline.

“A lot of maintenance people don’t take into consideration how the driver feels when he’s driving,” he adds. “They just want to get as much life out those parts as they can.”

Brake stroke indicators are a very inexpensive way of visually checking brake adjustment. They need to be calibrated and drivers need to understand how to use them. After that, they are almost infallible.

A Commonsense Approach to Truck Brake Maintenance

Basing a brake maintenance program and PM intervals on old established norms won’t work anymore, particularly where fleet vehicles are exposed to harsh de-icing chemicals, like in the Northeast and Midwest. Wheel-end components just don’t last as long as they used to.

Fleets can ill-afford the asset downtime and driver dissatisfaction associated with unplanned repairs. Stuart’s go/no-go criteria has changed from so many thousand miles per 32nd of lining thickness, to “will it make it to the next PM?”

Of course, that judgment is subjective, and every fleet is different. Duty cycles, terrain, and even climate affect brake life; what works for one fleet probably can’t be evenly applied to another.

However, there is value in benchmarking your fleet against peer fleets. The TMC/FleetNet Vertical Benchmarking Program or the State of Heavy-Duty Repair report, issued annually by Fullbay, can provide some insight.

If your costs and touch-time figures are similar compared to peer groups, you’re probably in the ballpark. If you’re off the mark, maybe you need to rethink how you do brake maintenance, and how effective your maintenance program actually is.

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