How to Check Brakes on a Semi Truck

Truckers from to the farthest stretches of road know how important brakes are to a safe and successful journey. These advanced systems function at the highest capacity to handle the incredibly immense loads a semi-trailer truck places on them and are a major factor in a semi truck’s lifespan. This is why their failure can be the cause of serious accidents, and why passing an inspection is necessary for continued service with a rig. Knowing how to check disc brakes on semi truck rigs means safely trailering around and beyond, whether on the steepest grades or in the city. Learn how to check brakes on a semi truck with the service specialists at Rechtien International Trucks.

Checking Air Disc Brakes: In-Depth

80,000 pounds barreling down the highway is a lot to handle, even for the most sophisticated braking systems. Learning how to check disc brakes on a semi truck can mean the difference between a successful trip and long delays or much worse. As air disc brakes (ADB’s) are becoming more popular, the difference in their maintenance from drum brakes may be unfamiliar for many truckers. See below for how to check disc brakes on a semi truck like the pros:

  1. Although ADBs are known for their higher temperature performance, checking your brakes cold is the first step to a proper reading.
  2. Next, based on the square-inch area of the chamber diaphragm and the applicable markings thereby, confirm the chambers’ size. If illegible, you can use a specifically designed caliper to get the correct size measurement.
  3. Note if you have long-stroke chambers, easily identified by their square-shaped airline ports and/or a trapezoidal tag under the clamp bolt indicating the stroke.
  4. The stroke length and chamber size directly determine what your readings should be. If you aren’t able to obtain this information, consult with a technician or the manufacturer
  5. Reference this information with the adjustment limit for your particular brakes as you fill the primary and secondary air tanks to between 90 psi and 100 psi.
  6. Precisely mark the pushrod at a fixed point with some chalk or marker pen. Many prefer to mark directly next to the chamber to make the math simpler.
  7. Apply and hold full pressure to the service brake pedal.
  8. Measure the distance the pushrod has traveled. If you marked directly next to the chamber the first time, simply measure the distance between the mark and the chamber.
  9. If your adjustment limit is within the prescribed range, you’re all set! For 16L chambers, for instance, the adjustment limit is 2 inches. If outside of the limit, you should have your brakes checked and possibly replaced by a service technician.

How to Check Brakes on Your Semi Truck: Brief Test and Tips

While knowing the correct way to check brakes on a semi truck is essential information for any trucker, no one has the time to constantly check each brake chamber. There is a recommended baseline for a brief check to see if a larger, in-depth look should be taken, and while brakes should be regularly checked and maintained, this should give you a good idea of your condition:

  1. Chock and secure the vehicle.
  2. Climb beneath, then use your hand or a suitable pry bar to pull back on the pushbar away from the brake chamber
  3. Measure how much play is present in the pushbar’s range of motion
  4. If the measured free-stroke distance exceeds ¾ inch (19mm), there is a high likelihood the brake is out of adjustment.
  5. Proceed to a trusted service center or perform the more rigorous test yourself to ensure your continued functionality

Keep Your Rig Functioning at Its Best with Rechtien International Trucks

Whether you want all the details on how to care for your semi truck tires or you simply want reliable trucks for your fleet, you can find it at our location. We’re always updating our blog with the latest updates to keep you informed on staying fuel efficient on long journeys and more. So contact us today at Rechtien International Trucks to get to know your rig inside and out, while we tackle the road’s toughest challenges together.

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