Breaking down brakes

by James Menzies

Brakes continue to be the trucking industry’s greatest pain point when it comes to vehicle-related out-of-service defects. However, there are steps fleet managers, maintenance departments, and even drivers can take to greatly reduce a carrier’s brake-related defects.

It starts with PM
Having a good preventive maintenance (PM) schedule in place is critical to identifying brake-related defects early, says Joseph Kay, director of brakes with Meritor.

“I’d start with making sure that preventive maintenance is being conducted at regularly-scheduled times,” he explains. “It’s really important for the fleet manager to know the vehicle, and the duty cycle those vehicles are subjected to.”

He reminds that the wheel-end is on the unsprung side of the suspension, meaning pot holes and other bumps can contribute significant fatigue to wheel-end components, including brakes. They’re also subject to all the corrosive de-icing agents being sprayed on the roads.

“There are some pretty nasty contaminants out there that can play havoc on the parts,” Kay says, adding technicians should regularly grease wheel-end components to protect against these corrosive agents.

Kevin Pfost, technical services coordinator, Bendix Spicer Foundation Brake, agrees that technicians should be inspecting the brakes every time the truck visits the shop.

“If you bring a truck into a garage, it takes about 10 minutes to go through and actually measure the brake’s stroke,” Pfost says. “Most maintenance departments will tell you they don’t have enough time. But if they bring the truck in for any reason, take that extra five or 10 minutes to measure brake stroke while you have the truck in there.”

Understanding slack adjusters
Kerri Wirachowsky, director of roadside inspection programs for the Commercial Vehicle Safety Alliance (CVSA), says some fleets continue to use manual slack adjusters on trucks built after 1994, not realizing that it’s illegal to do so.

In one instance, she recalls, a fleet stocked up on manual slack adjusters because they were on sale, and placed them on all its vehicles.

“Don’t do that,” she emphasized on a recent brake safety webinar hosted by ERoad. “When you do that, you are subject to violations.”

She says manual slack adjusters are easily identified because they have three holes in them instead of just one. They’re currently only allowed on trucks built prior to 1994. Also, automatic slack adjusters should never be manually adjusted. And if a brake is out of adjustment, don’t assume the slack adjuster is to blame, points out Meritor’s Kay.

“If the brake is out of adjustment, it could be the adjuster that’s bad or it could be something else,” he says. “Air chambers, bushings, bearings, camshafts – different components can create out-of-adjustment conditions, so just going and adjusting the brakes could be masking a bigger problem.”

Pfost says technicians should be reminded to lubricate the automatic slack adjusters during PMs, but he said manually adjusting an automatic slack adjuster can cause internal damage to the component.

Drivers need to do their part
Wirachowsky says roadside inspectors are regularly frustrated when they find obvious brake defects that should have been discovered during a proper pre-trip inspection.

“I’m not suggesting drivers can find them all, but I’m suggesting, in most cases, they can find more than they do,” she says. “I’ve seen drivers do trip inspections and check their tires, rims, wheels, but I don’t see them looking underneath the truck at the pushrod stroke and the broken springs and other things they could potentially find before I, as an inspector, find them. We all want a safe truck on the road and if they can find it before an inspector, great, because that is what we are trying to do and then they can get it repaired at a facility rather than at the side of the road where it costs carriers thousands of dollars more.”

Drivers, during their pre-trip inspection, should also look for air hose chafing, which Wirachowsky notes is the second most common brake violation outside of adjustment, and something a driver can easily see. This is often a problem when the air host is laid across the catwalk or deck.

“A crack in the spring brake housing is an automatic out-of-service violation, and the driver just needs to bend at the waste to be able to see that,” she adds.

From behind the wheel, there are other symptoms of brake issues that drivers should be aware of, Pfost says.

“You may have a brake pull when you apply the brakes,” he explains. “You can get pull from one side to the other. The other thing you could be looking at is you have to apply more brake pressure to get the vehicle to stop under normal stopping. Grinding noises. Even friction smell. Let’s say you have a brake that’s hanging up, you can smell that friction burn. It’s not a good smell. So, those are a couple things that a driver if he is listening and paying attention, would notice.”

Switching to air disc brakes
One way to greatly reduce t he risk of brake violations is to switch to air disc brakes, where the individual brake components are contained out of sight. But that doesn’t mean disc brakes are maintenance-free, or that they don’t have to be inspected.

“With a disc brake, your inspection is visual. You’re looking for cracks, or you look up between the wheels and the caliper. You’re looking where the pads sit and you look for mismatched pad thickness,” Pfost explains. “Then you’ll move the caliper and you’ll check caliper movement and you want to make sure there’s running clearance. People get it in their heads that disc brakes are maintenance-free, but you still have to visually inspect this.”

Kay agrees, suggesting drivers and technicians carefully inspect disc brakes for road damage. Disc brakes continue to be standardized by more truck manufacturers and more fleets are making the switch to reduce roadside violations as well as to provide better stopping performance.

They’re even being touted as a driver benefit, according to a new white paper from Haldex.

“Fleets today are looking for any way they can get a leg up in recruiting and retaining good drivers and having vehicle equipped with air disc brakes sends a message that they are serious about their safety,” the Haldex white paper said. “There is also an argument to be made that the pedal feel of a truck with air disc brakes is similar to that of a passenger car might open up the driver pool similar to how automated transmissions drew more people to the vocation.”

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