Sespel patents air suspension without separate shock absorbers for axle assemblies

The innovative suspension uses distinctive air springs that act as both dampers and elastic elements. An additional air-damping reservoir connects to each air spring through an extra opening, providing airflow that produces a pneumatic damping effect.

Each air spring has two air chambers connected by an opening. Resistance to airflow between the chambers, and the resulting pressure increase, produce the damping force previously provided by shock absorbers.

Conventional air suspension consists of rubber air springs above each wheel; an air reservoir for rapid inflation or deflation at low speeds without engaging the compressor; trailing spring arms that securely connect the axles to the platform and prevent additional loads on the air springs; and shock absorbers that damp oscillations when travelling over uneven surfaces.

The main drawback is shock absorber wear and the need for replacement. Wear often goes unnoticed by the driver, with consequences usually becoming apparent in critical situations. Faulty shock absorbers can also cause the vehicle to lose road contact on slightly uneven surfaces that induce resonant wheel oscillation.

Comparative tests by TÜV showed that a truck’s braking distance increases by 28.3% when its shock absorbers are 50% worn.

In July 2022, Sespel began manufacturing a new range of tank semi-trailers with innovative air suspension without separate shock absorbers. The resulting suspension is simple and compact, offers excellent elastic properties and adjustable ground clearance and lifting force, and improves ride performance.