There’s more to out-of-service numbers than meets the eye. The value is in the data.  -  Photo: Jim Park

There’s more to out-of-service numbers than meets the eye. The value is in the data.

Photo: Jim Park

There are bits of gold in the published results of all of Commercial Vehicle Safety Alliance’s vehicle inspection initiatives, if you bother to poke around in the numbers. Not all the numbers make it into the press releases, but the CVSA has accumulated some amazing inspection data.

If you’re cracks and crevices in your maintenance procedures, CVSA’s listing of out-of-service defects is a good place to start. You may not have enough inspection exposure to see trends in your own operation, but the OOS items provide good insights on industry-wide trends.

CVSA is always willing to send me additional information when I ask for it -- in my role as a reporter. I’m not sure how that would work for fleets, but I think fleet members can access more of the results than are typically released to the media.

CVSA, last week, published the results from Brake Safety Week 2022. During the week of August 21-27, inspectors here and in Canada and Mexico conducted more than 38,000 brake-focused inspections. Of that number, 13.3% (5,069 trucks and trailers) were placed out of service for brake-related critical vehicle inspection item violations. You have to dig a little to learn specifically what sidelined those trucks.

I found the national out-of-service rates interesting. For many years, Canada consistently had lower brake-related OOS rates than the US, but over the past four or five years, our northern neighbor has slipped. This year was typical, with Canada reporting a 17.8% OOS rate. The US was second at 13.6%, leaving Mexico with the lowest OOS rate of the three, at just 2.5%.

Remember the brouhaha about a decade ago when Mexican trucks we given limited access to US highways? I don’t know, maybe there’s something in the way they inspect trucks in Mexico, or maybe there’s something in the way Mexican carriers maintain their trucks. That’s beyond my paygrade.

Brakes Get Two Top Spots

CVSA usually reports the top five vehicle OOS violations. Brakes are always on this list. In addition to lights, tires and cargo securement violations, brake systems and brake adjustment or defective brakes always make the top five.

Is there room in your yard for a brake triage inspection lane? It seems there’s a need for such periodic inspections. We all know drivers are supposed to check their brakes every day, but honestly, when was the last time you saw a driver on his or her back out in the dirt measuring brake stroke?    

As in industry, we need to come up with a better way to carry out brake adjustment inspections than rely on drivers to do them. If you get right down to it, a driver cannot do a mark-and-measure inspection alone. Unless they have some jury-rigged device for holding the brake pedal at 90-100 psi application pressure, that cannot apply the brakes and measure brake stroke at the same time.

ABS Problems Hint at Deeper Problems

ABS violations always place highly on the OOS rankings. We all know about that damn light, but that really all the inspectors have to go on at roadside. Short of hooking up a diagnostic tool to the ABS control module, what other way is there to check ABS function.

But here’s the deeper issue. The light only indicates a malfunction, it’s not very specific. What if some particular malfunction also renders your expensive electronic stability control system inoperative, or your collision mitigation technology?

Which brings me to the next issue. The violation heading “defective brakes” covers a multitude of sins. Depending on how the inspector writes a violation, it could name a specific fault --which they often do -- or just list defective.

Those aforementioned advanced safety systems rely heavily on properly functioning brakes. If there’s some defect present, like a seized clevis pin or a broken return spring, maybe worn cam bushings, the brakes may be unable to deliver all the stopping power the truck needs.

Performance-Based Brake Testing

Interestingly, this year CVSA included results from the jurisdictions that use PBBTs (performance-based brake testers) for roadside inspections. These machines assess the braking performance of a vehicle. This is done through direct measurements of the brake forces at each wheel end, axle or for the entire vehicle.

According to CVSA, roller dynamometers and flat plate brake testers can determine brake forces regardless of the brake type (disc vs. drum) or energy supply (air, hydraulic or electric). In addition, PBBTs based on mechanical or electronic decelerometers can assess the overall vehicle braking capability of individual wheels through a stopping performance test in which deceleration and/or stopping distance is obtained.

The sight of a performance-based brake tester in use at an inspection station 
can strike fear into the hearts of truck drivers. That’s one time the driver 
shouldn’t charged with a brake violation.  -  Photo: Jim Park

The sight of a performance-based brake tester in use at an inspection station
can strike fear into the hearts of truck drivers. That’s one time the driver
shouldn’t charged with a brake violation.

Photo: Jim Park

In other words, PBBTs measure how well the brakes are working, not just whether any defects or deficiencies are present. While visual inspections can indicate a potential problem with a brake component, actual brake performance cannot be determined by visual inspection. PBBTs, on the other hand, may give a brake a passing grade if it delivers the performance, regardless of the presence of defects, such as chaffed hoses, for example. PBBTs will most certainly reveal adjustment issues too.

With PBBTs, a vehicle can be placed out-of-service if the total brake force, as a percentage of the gross vehicle weight or combination weight, is 43.5% or lower (393.45(a)(1)). For example, an 80,000-pound truck would have to produce at least 34,800 pounds of brake force. That’s a measurable value on PBBT.

I think for than a few fleet maintenance folks might be surprised to learn that brake performance is part of the out-of-service criteria. Beyond FMVSS-121, which applies only to new vehicles, there are few published performance standards that must be met by in-service brakes.

PBBTs can reveal problems like glazed or low-friction brake linings, application and release timing, broken parking springs, and a host of other issues that may not be detected with only visual inspections.

Some years ago, I met a fellow who had opened a brake shop. He had a PBBT, and he intended to build a clientele by offering tests through which he could solve fleets’ brake problems. The truth was, he found so many problems that fleets became wary of putting their trucks on the tester fearing how much it would cost to remedy the problems.

The machine revealed incorrect brake valves through timing values, out-of-round brake drums, non-concentric wheel mounting, lining material mismatches, and more.

A problem like a crimped hose would likely be caught in a visual inspection. 
But if it was missed, it would show up on PBBT, probably as low application 
force at a wheel or incorrect timing.  -  Photo: Jim Park

A problem like a crimped hose would likely be caught in a visual inspection.
But if it was missed, it would show up on PBBT, probably as low application
force at a wheel or incorrect timing.

Photo: Jim Park

In one example he liked to talk about, he found an incorrect but identical looking brake valve (R-8, should have been R-8P), which upset the timing of the converter dolly brakes. He said the resulting 0.36 second delay resulted in a 30-ft delay in braking behind the lead trailer during a panic stop. The brakes on lead trailer would be required to work harder to compensate with every application. So, a problem the fleet didn’t think was worth fixing was actually increasing brake wear and costing them money.

But that’s just one tale among thousands where digging a bit beyond the obvious has some reward.

So, when you read a CVSA press release talking about how may trucks inspectors placed out of service, ask yourself whether your trucks could have been one of them.

Those who know me are aware that I love talking about brakes. As unsexy as they are, I think they are one of the most under-rated systems on trucks. I was recently a guest, along with Steve Keppler, co-director, Scopelitis Transportation Consulting, on the Fleet Champion podcast from Whip Around. Wanna know how I really feel about brakes? Give it a listen.

Author

Jim Park
Jim Park

Equipment Contributing Editor

A truck driver and owner-operator for 20 years before becoming a trucking journalist, Jim Park maintains his commercial driver’s license and brings a real-world perspective to Test Drives, as well as to features about equipment spec’ing and trends, maintenance and drivers. His Ultimate Test Drive and other videos bring a new dimension to his trucking reporting. He is the host of HDT Talks Trucking podcast.

View Bio

A truck driver and owner-operator for 20 years before becoming a trucking journalist, Jim Park maintains his commercial driver’s license and brings a real-world perspective to Test Drives, as well as to features about equipment spec’ing and trends, maintenance and drivers. His Ultimate Test Drive and other videos bring a new dimension to his trucking reporting. He is the host of HDT Talks Trucking podcast.

View Bio
0 Comments