In trucking as in life, there’s no substitute for being prepared – whether it’s the next load, storm, or inspection. And inspections are top of mind right now in the North American commercial vehicle industry as one of the biggest touchpoints on the calendar is approaching: Brake Safety Week, August 21-27. The annual weeklong event run by the Commercial Vehicle Safety Alliance (CVSA) examines vehicles across the United States, Canada, and Mexico. The team at Bendix Commercial Vehicle Systems LLC (Bendix) offers suggestions on getting ready.
“During last year’s CVSA Brake Safety Week, 12% of the 35,764 vehicles inspected were placed out of service for brake-related issues,” said Fred Andersky, Bendix director – demos, sales, and service training. “So many aspects of safe vehicle operation are directly impacted by what goes on at the wheel-ends and in the braking system that you really can’t overstate the importance of keeping up with maintenance and inspection of those areas. From stopping power to the performance of higher-level technologies like collision mitigation, everything is linked to how well the brakes and wheel-ends perform when they’re needed. That’s why these inspections matter so much, and why Bendix puts the word out with practical tips for being prepared and staying safe.”
Brake Safety Week is part of CVSA’s Operation Airbrake initiative, an outreach and enforcement campaign that aims to reduce the number of highway crashes caused by faulty brake systems on commercial motor vehicles. The event involves local, state, provincial, territorial, and federal motor carrier safety officials in the United States, Canada, and Mexico inspecting large trucks and buses, focusing on brake system violations.
What to Expect
Brake Safety Week roadside inspectors conduct North American Standard Inspections, which cover a range of driver qualifications, documentation, and vehicle equipment conditions. They’ll be checking for:
- Missing, nonfunctioning, loose, contaminated, or cracked parts
- Holes caused by rust and through rubbing or friction
- Broken springs in the spring brake housing section of the parking brake
- Air leaks around brake components and lines
- Air pressure in the target range of 90-100 psi
- Slack adjusters not at the same length
- Mismatched air chamber sizes across axles
- Warning device functionality (such as antilock braking system indicator lights)
Inspectors will also look for brake hose and tubing chafing violations – the focus of this year’s Brake Safety Week.
How to Get Ready
“Pre-, post-trip, and regular inspections can go a long way toward catching some obvious violations, including loose hoses or damaged components like air chambers or pushrods,” said Mark Holley, Bendix director of marketing and customer solutions, Wheel-End. He recommends the following:
Every day:
- Check for damaged or loose-hanging air chambers, pushrods, or slack adjusters.
- Make sure slack adjusters on each axle are extended out to the same angle. Different angles can indicate an out-of-adjustment brake or a broken spring brake power spring.
- Examine tubing and hose condition, positioning, and connections.
Every week:
- Perform a 90- to 100-psi brake application with the wheels chocked and the parking brakes released, and listen for leaks.
- Check air disc brake rotors for cracks.
- Inspect drum brake linings for wear and cracks.
Every month:
- Check for moisture in the air system to prevent contamination that leads to component deterioration and system leaks.
“It’s also worth greasing the S-cam brake tubes and automatic slack adjusters any time you’ve got a vehicle in the shop,” Holley said. “This quick process helps prevent rust and corrosion and helps keep the slack functioning properly.”
Regarding brake hose and tubing chafing, the focus of Brake Safety Week this year, Bendix recommends watching for two typical causes. First is improper routing and clipping, which can cause hoses to rub together while the vehicle is operating. Preventive measures include periodic inspections to ensure tie straps, clips, and any brackets are not damaged or broken. The second typical cause is improper hose length – an overly long replacement hose is susceptible to chafing. Damaged hoses should be replaced.
“In addition, from the larger perspective, never underestimate the significance of communication between drivers and technicians,” Andersky said. “A driver out on the road may be the first one to notice an issue with the truck. Being able to tell the technician what happened, where, and other details such as weather conditions is important – as is the technician asking questions to get a clearer understanding of the situation.”
Andersky went on to describe how it's particularly important to take note of any individual issue with a driver in order to approach maintenance and inspections holistically. As with any interconnected system, such as brake and advanced safety technologies, any element that an inspector may search for at Brake Safety Week is consequential and could be indicative of larger maintenance issues, and thus all issues must be treated with equal weight.
How drums and discs differ
Where Brake Safety Week is concerned, air disc brakes and drum brakes have a few differing maintenance needs.
“Key among the differences is the measurement of brake stroke,” Holley said. “Because air disc brakes include an internal adjustment mechanism, their brake stroke is not measured externally, as is the case with drum brakes. The internal adjustment mechanism significantly lowers the risk of out-of-adjustment violations.”
Measuring a drum brake’s chamber stroke is a matter of checking the distance from the air chamber to the clevis pin with the brakes released, and then again after a fully charged brake application. The difference between these is the brake stroke, and its maximum length depends upon the brake chamber type and size.
Improperly adjusted brakes can also drag–impacting fuel efficiency and speeding up pad wear–or experience decreased stopping power. Bendix has developed an infographic to note the differing maintenance needs of air disc and drum brakes.
