What Kelderman Suspension Is

Kelderman suspension is an air suspension system designed for heavy-duty trucks and trailers, primarily used in commercial hauling and specialized transport. Unlike traditional steel spring suspensions, Kelderman uses pressurized air chambers to support the vehicle's weight and absorb road shock. The system automatically adjusts air pressure based on load, which means the ride height and stiffness change depending on what you're carrying.

Kelderman suspensions are built by Kelderman Air Suspension, a manufacturer based in the Netherlands that specializes in aftermarket and OEM suspension systems for trucks, trailers, and commercial vehicles. You'll find these systems on dump trucks, flatbeds, livestock trailers, and other heavy commercial rigs where load capacity and ride control matter.

Key Takeaways

  • Kelderman air suspension uses pressurized air instead of steel springs to support vehicle weight and absorb bumps.
  • The system automatically adjusts stiffness and ride height as your load changes, keeping the truck level whether empty or fully loaded.
  • Air suspensions reduce wear on cargo, the truck frame, and the road compared to traditional spring systems.
  • Maintenance involves checking air lines, valve function, and compressor operation; air leaks are the most common failure point.
  • Kelderman systems cost more upfront than steel springs but often pay back through longer component life and reduced cargo damage.

How the Air Suspension System Works

A Kelderman suspension has four main parts: an air compressor, air springs (the pressurized chambers that replace coil or leaf springs), control valves, and an air dryer. When you load the truck, sensors detect the added weight and signal the compressor to pump more air into the springs. This increases pressure inside the air chambers, which stiffens the suspension and raises the truck back to level. When you unload, the system vents air and softens, lowering the ride height.

The air dryer is critical because moisture inside air lines causes rust and valve failure. It removes water vapor from the compressed air before it enters the springs. Without a working dryer, you'll develop corrosion inside the air chambers and control valves, which eventually leads to leaks and loss of pressure.

The control valves regulate how much air flows into or out of the springs. They respond to height sensors mounted on the axles or frame. If the truck sags under load, the sensor tells the valve to open and let more air in. If it rises too high when unloaded, the valve vents air to bring it back down. This automatic leveling happens continuously while you drive.

Advantages Over Traditional Spring Suspension

Air suspension spreads weight more evenly across all axles because it adjusts pressure independently on each corner. This means less stress on individual components and a longer service life for the frame, axles, and tires. The smoother ride also reduces shock to cargo—important if you're hauling fragile goods, livestock, or perishables.

Because the system maintains level ride height regardless of load, you avoid the sagging that happens with steel springs when fully loaded. This keeps the truck's geometry correct, which improves handling and braking performance. You also get better traction because weight stays distributed evenly across all wheels.

Maintenance costs often come out lower over time. Air springs last longer than leaf springs, and the reduced shock means brake pads, tires, and frame components wear more slowly. However, the upfront cost is higher, and repair work requires a technician familiar with air systems.

Common Maintenance and Failure Points

Air leaks are the most frequent problem. They can occur in the air springs themselves, at connection points where lines attach to valves, or in the dryer. A slow leak may not be obvious at first—the truck will straightforward sag more than usual under load, or take longer to level out after you park. You may also hear a hissing sound when the compressor runs, which signals air escaping.

The air dryer can fail if it becomes saturated with moisture or if the cartridge inside isn't replaced on schedule. When this happens, water enters the air lines and causes rust inside the springs and valves. Corrosion then creates pinhole leaks that are hard to locate and repair.

Control valves can stick or fail to respond to sensor signals, which leaves the suspension at a fixed height instead of adjusting automatically. This usually happens because of corrosion or debris inside the valve. The compressor itself can wear out, especially if it runs constantly because of a leak elsewhere in the system.

Regular maintenance includes checking all air line connections for tightness, inspecting the air dryer cartridge and replacing it according to the manufacturer's schedule, and testing the compressor to may support it builds pressure normally. Many shops recommend a full system inspection annually for commercial vehicles.

When Kelderman Suspension Makes Sense

Kelderman systems are most cost-effective for trucks that carry variable loads—dump trucks, flatbeds, and livestock trailers are common examples. If your load weight changes significantly between trips, the automatic leveling saves you from having to manually adjust anything or accept a sagging ride.

They're also a good choice if you haul cargo that's sensitive to shock or vibration. Produce, electronics, and other delicate goods arrive in better condition with air suspension. The smoother ride also reduces driver fatigue on long hauls.

If you run a truck primarily empty or at a consistent weight, a traditional spring suspension may be simpler and cheaper to maintain. The decision depends on your specific use case, budget, and how much you value the ride quality and automatic load compensation.

Repair and Replacement Considerations

When an air spring fails, you typically have to replace the entire chamber rather than repair it. Replacement cost varies depending on whether you're working on the tractor or trailer and how many springs need replacement. Labor time is usually two to four hours per axle.

If the compressor fails, replacement is more involved because it's often belt-driven from the engine and requires disconnecting multiple air lines. This is a job for a shop with air suspension experience. Attempting it without proper tools and knowledge can leave you with leaks or incorrect pressure settings.

Some shops can rebuild control valves, but replacement is often faster and more reliable. Parts availability depends on your location and whether you're working on a common truck model or a specialty vehicle. Kelderman parts are generally available through truck dealers and suspension specialists, though lead times can vary.

Frequently Asked Questions

Can I convert a truck with steel springs to Kelderman air suspension?

Yes, Kelderman offers conversion kits for many truck models. The job requires removing the old spring mounts, installing new air spring brackets, running air lines, and mounting the compressor and control valves. It's a significant undertaking that typically takes a shop several days and costs several thousand dollars, but it's possible on most commercial trucks.

How often should I replace the air dryer cartridge?

Replacement intervals vary by manufacturer and driving conditions, but most recommend every 12 to 24 months for heavy commercial use. If you operate in humid climates or short-haul routes where the compressor runs frequently, replace it more often. Check your system manual for the specific interval for your truck.

What does it mean if my truck won't level out after I load it?

The compressor may not be building enough pressure, the control valve may be stuck, or there's a leak in the air springs or lines. Start by listening for a hissing sound (sign of a leak) and checking that the compressor runs when you load the truck. If the compressor runs but pressure doesn't build, have a shop test the system with a pressure gauge to pinpoint the problem.

Is air suspension more expensive to insure?

Insurance rates depend on your carrier and the specific truck, not the suspension type. However, some insurers offer discounts for air suspension because it reduces cargo damage and improves vehicle stability. Ask your agent whether your policy reflects this.

Can I drive safely if I have a small air leak?

A very small leak may not affect when ready safety, but you should have it repaired soon. The truck will sag gradually as pressure drops, which changes handling and braking performance. If the leak is large enough that the truck won't level out or sags noticeably within a few hours, do not drive it—have it towed to a shop instead.