How to Maintain Trailer Air Suspension & Ride Height Valves

A technical guide to maintaining semi trailer air suspension systems — covering air springs, leveling valves, leaks, and calibration tips to ensure stable load balance and driving comfort.

Air Suspension Trailer Maintenance
📅 Published on 2025-11-14 | ✍️ Semi Trailer News Engineering Desk

Trailer air suspension and leveling valve system

Image: Semi trailer air suspension layout showing air springs, leveling valve, and control lines

💨 The Role of Air Suspension

Air suspension replaces traditional steel springs with **air bellows** that automatically adjust to maintain constant ride height under varying loads. It improves stability, protects cargo, and reduces wear on both the trailer and road surface. Proper maintenance ensures long service life and optimal ride quality.

⚙️ Main Components

Air Springs (Bellows): Flexible rubber bags filled with pressurized air to support the load.
Ride Height Control Valve: Regulates air pressure to keep trailer height constant.
Pressure Lines & Fittings: Connect air springs to supply tanks and control valves.
Dump Valve: Releases air when parked or during coupling/decoupling operations.

🧰 Common Issues & Troubleshooting

Symptom	Possible Cause	Solution
Trailer tilts to one side	Faulty height valve or air leak in one bellow	Check for leaks, replace valve
Slow height correction	Restricted airline or debris in valve	Clean or replace blocked line
No air in suspension	Supply pressure too low or damaged dump valve	Verify tank pressure and valve function
Ride height fluctuates	Improper valve linkage adjustment	Recalibrate lever according to spec

🔍 Ride Height Valve Calibration

Each trailer has a manufacturer-specified **nominal ride height** (e.g., 1,250 ±10 mm from ground to frame). To calibrate:

Place the trailer on level ground with normal load.
Measure from axle center to reference point on chassis.
Loosen the valve linkage and adjust until desired height is reached.
Tighten linkage and test by loading/unloading to confirm stability.

🔧 Maintenance Tips

Inspect air bellows monthly for cracks, bulges, or rubbing against other parts.
Spray soapy water on suspected leak areas — bubbles indicate air loss.
Clean leveling valves with dry compressed air; avoid oil contamination.
Replace worn rubber hoses with OEM-grade heat-resistant lines.
Keep the system dry — drain air tanks daily to prevent moisture damage.

🌍 Integration with EBS Systems

In modern trailers, **EBS integrates with air suspension** to optimize braking force according to load weight. Pressure sensors in the suspension system send signals to the EBS ECU, balancing brake force distribution across all axles. Regular maintenance ensures accurate load sensing and prevents premature brake wear.

🏁 Final Thoughts

A well-maintained air suspension system ensures consistent ride height, smooth handling, and minimal tyre wear. Simple preventive care — leak checks, valve calibration, and moisture control — keeps your fleet operating safely and efficiently year-round.

🔗 Related Articles

Are Chinese Semi Trailers Really Low Quality? Myths vs Reality

An unbiased analysis of Chinese semi trailer manufacturing quality compared to European standards. Examining material...

Predictive Maintenance for Semi Trailers: Sensors, Telematics & Failure Prevention (2025 Guide)

Learn how predictive maintenance technologies—sensor systems, telematics, brake temperature monitoring and weld-failu...

Robotic Welding in Lowbed Trailer Production: Precision, Efficiency & Durability

An in-depth look at how robotic welding revolutionizes lowbed trailer manufacturing — covering welding automation, qu...