brakes

When you press the brake pedal on your truck, you expect an instant response. Yet any number of issues can cause your vehicle’s braking systems to fail, increasing your risk of a serious accident while putting you and your cargo in danger. That’s why maintaining your truck’s braking system is so important and a major part of your Pre-Trip Inspection.

To ensure brake safety every day of the year, here are 10 tips to help ensure your brake linings and pads are ready for the road:

1. Inspect all the parts of the brake linings and pads that you can see during pre- and post-trip inspections.

2. Check for signs of missing or damaged brake lining, such as grooves in the drum from rivet contact.

3. Look at the shoe-to-drum clearance and ensure that there is adequate lining on the shoe.

4. Try to find any signs of leaks from the hub or other components that may contaminate the lining or pad surface.

5. Look for any missing lining blocks.

6. Scan for visible cracks or voids in the lining block.

7. Check for any exposed rivets or lining blocks that look loose on the shoe.

8. On disc brakes, pay close attention to the condition of the rotor. Look for either metal-to-metal contact or heavily rusted rotors across the entire friction surface on either side.

9. Make any repairs in accordance with the brake manufacturer’s requirements and guidelines.

10. Note any brake lining or pad-related issues in your driver vehicle inspection reports and report them to the motor carrier.

In addition, always check for these brake-related items during pre- and post-trip inspections:

  • Any missing, non-functioning, loose or cracked parts
  • Audible air leaks coming from around the brake components and lines
  • Slack adjusters that are different lengths
  • Air pressure below 90-100 psi
  • Rust holes or broken springs in the brake housing section of the parking brake
  • Malfunctioning ABS warning lamps

Remember, a properly conducted pre-trip inspection will go a long way toward passing a brake inspection — and keeping you and those around you safe.

The brake system on a commercial motor vehicle (CMV) must perform constantly and under all conditions. While both air disc brakes and S-cam drum brakes can get the job done, many manufacturers have made air disc brakes standard and the adoption rate for air disc brakes is increasing.

“The biggest difference between air disc brakes and S-cam drum brakes is disc brakes have a shorter stopping distance and you eliminate several components, so there are less maintenance items on air disc brakes,” said Chris Hough, vice president of maintenance at Penske Truck Leasing.

For example, air disc brakes do not need a slack adjuster, but S-cam brakes do. Kerri Wirachowsky, director of inspection programs for the Commercial Vehicle Safety Alliance (CVSA), said brakes out of adjustment is the number one violation drivers receive.

“Generally, when a vehicle is put out of service for brakes being out of adjustment, it is because the automatic slack adjuster did not adjust correctly. It could be because it was not maintained or because it failed,” Hough said.

Additionally, air disc brakes don’t experience brake fade, or result in stopping power, after repeated use. At higher speeds, disc brakes have a better response at higher temperatures.

Initially, the adoption of air disc brakes was slower because they were more expensive and roadside service didn’t always have parts, Wirachowsky said. “As more and more get introduced into the market, the more the price comes down and the more familiar technicians get with them and can do roadside repair. I think over the course of time, we’re going to see more go that way,” Wirachowsky said.

Penske Truck Leasing made air disc brakes standard on tractors within its rental fleet in 2017, and Hough expects to see increased adoption on trailers as well. “Over time, as technology continues to improve and air disc brakes become more economical, which they are, we’ll probably see the industry transition to air disc brakes on trailers,” Hough said.

Brake Maintenance

When maintained and installed correctly, both brake types meet required safety standards, but maintenance is critical for all systems. Disc brakes are sometimes erroneously characterized as being maintenance free and they are not, and brake systems, whether they are disc brakes or drum brakes, require attention.

Hough said brakes must be checked at every preventive maintenance inspection and drivers should regularly check brakes during pre- and post-trip inspections. Plus, brakes need to be lubricated or greased at set intervals and slack adjusters on S-cam drum brakes have to be tested.

“During a PM inspection, we measure the applied brake stroke. With the foot pedal applied, we measure the total distance the slack adjuster is traveling so we know it is working correctly,” Hough said. “They’re dependable, but from time to time, one will fail.”

Hoses and tubing have been an important focus area for CVSA inspectors for several years because brake hose chafing is another common violation. “You could have belly hoses on the trailer that are rubbing or the gladhand hoses are too long and they rub on the catwalk,” Wirachowsky said. “That is what we look for, and drivers should be looking for that during their inspection.”

If a hose rubs up against something until it punctures the liner of the hose, it will leak air. “If it is leaking air, the brakes won’t work correctly,” Hough said, adding that some hoses are difficult for drivers to inspect during pre- and post-trip inspections. “That is why it is so important during a PM inspection to check for any type of chafing.”

Overall Safety

According to the Federal Motor Carrier Safety Administration’s (FMCSA’s) latest Large Truck and Bus Crash Facts report, the brake system was the third most cited vehicle-related factor in fatal commercial motor vehicle and passenger vehicle crashes, highlighting the critical safety role brakes play in transportation.

Additionally, brake-related violations accounted for eight out of the top 20 vehicle violations in 2022, according to FMCSA’s Motor Carrier Management Information System. Plus, brake-related violations make up the largest percentage of all out-of-service violations cited during roadside inspections, CVSA reported.

Additional Information

CVSA has several brake sources available:

    If you haven’t recently checked all the components of your truck’s brake system, now is the time to get it done to keep you and others safe on the road. Plus, you'll be ready for your next inspection.

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    The Commercial Vehicle Safety Alliance (CVSA) and roadside inspectors are teaming up this week across North America to promote brake health and safety.

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