Got Questions? Hendrickson Ride Solutions

Q. What routine maintenance procedures do you recommend for air suspensions on trucks, tractors, and trailers? Why is it important to properly maintain those systems?

A. Routine maintenance on air suspension will consist of audible inspections, visual inspections, and adjustments. When performing an audible inspection, essentially you will be listening for air leaks from fittings, air lines, air springs, and the height control valve. Identifying air leaks is an important first step since it’s a requirement for the vehicle operator’s DOT pre-trip inspection. DOT regulations have a maximum allowable amount of air leakage which depends on the vehicle configuration. The rate of pressure loss should not be more than 2 psi per minute for single vehicles and no more than 3 psi per minute for combination vehicles. Additionally, air leaks can be an early indicator of a condition that can lead to a more serious problem such as a height control valve failure, a ruptured air spring, or a broken air fitting.

Visual inspections on an air suspension are similar to inspections performed on a mechanical suspension except for the air system components such as the air springs, air lines and height control valve. The air springs and air lines need to be visually inspected for signs of rubbing or chaffing that can lead to a complete failure of the component during operation. Air lines should also be inspected for excessive bends or kinks that can restrict air flow that will lead to a reduction in performance of the suspension and possible vehicle handling issues.

The height control valve, including the linkage which connects it to the suspension, needs to be inspected for damage such as bends or broken components that may be caused by road debris. Checking the vehicle’s ride height is important to ensure proper performance of the suspension during vehicle operation. If the ride height is found to be out of specification, the height control valve will need to be adjusted to correct this condition. Suspension manufacturers may have specific procedures to accomplish this adjustment, especially if the vehicle is equipped with dual height control valves. For this reason, it is recommended to follow the technical publication from the manufacturer.

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