Hydraulic or Air Suspension on Tractor-Towed Trailers

Stability, safety and precision in real-world operation

The choice of suspension is critical to how a tractor-towed trailer or hooklift performs under real operating conditions. The right suspension system affects not only driver comfort and safety, but also fuel consumption, tyre wear, soil compaction and the trailer’s long-term resale value.

At Metsjö, suspension is a core part of the overall design. Our philosophy is clear: stability, control and precision always come before cheaper solutions and lateral softness. Below we explain the differences between hydraulic suspension and air suspension – and why Metsjö’s hydraulic suspension sets a new benchmark for agricultural trailers and hooklift systems.

Why suspension is critical in modern agricultural transport

A modern agricultural trailer or tractor-towed hooklift is exposed to loads and conditions rarely encountered by conventional road vehicles:

• Extreme loads with a high centre of gravity, for example during silage or container transport

• Uneven terrain, soft fields and high demands on soil protection

• Rapid transitions between empty and fully loaded operation

• Relatively high transport speeds on poor road surfaces

In these environments, lateral stability of the suspension system is essential for both safety and operational economy.

Parabolic suspension (leaf springs) – why Metsjö has chosen not to use it

Parabolic suspension based on leaf springs is a common mechanical solution in the industry. However, Metsjö does not build trailers with parabolic suspension.

The reason is simple:
leaf springs provide insufficient lateral control. Under heavy loads and on uneven ground this can lead to oscillation and instability, creating safety limitations when handling high loads, tall bodies or demanding terrain.

Air suspension on agricultural trailers – comfort with limitations

Metsjö offers air suspension for trailers where transport comfort and automatic ride height adjustment are prioritised. The system is based on standard components from the truck industry and is generally less expensive than hydraulic suspension.

Advantages of air suspension:

• Excellent comfort during road transport

• Automatic ride height, especially beneficial with stiff tyres

• Low vibration levels on smooth surfaces

Metsjö standard:
All air-suspended axles are laser-aligned during installation, ensuring straight tracking, reduced rolling resistance and minimal tyre wear.

Limitations of air suspension:

• Air is compressible, making the system elastic

• Tall containers or hooklift bodies can cause lateral sway

• Reduced stability affects both safety and resale value

• Air bellows are sensitive to punctures and rough terrain, making air suspension less suitable for demanding field conditions

Hydraulic suspension – maximum stability and control

Hydraulic suspension is the foundation of Metsjö’s most successful trailer concepts. Because hydraulic oil is incompressible, the system delivers direct, stable and predictable behaviour regardless of load or driving conditions.

Suspension is achieved through controlled oil flow and a chassis design that actively manages forces both longitudinally and laterally.

Three technical pillars of Metsjö’s hydraulic suspension system

1. Laser-aligned axles
Extremely precise axle installation reduces lateral forces, lowers fuel consumption and allows the trailer to roll more freely than conventional solutions.

2. Angled hydraulic cylinders
The cylinder geometry provides the widest possible stability base within legal width limits, delivering outstanding roll stability in corners and on slopes.

3. Dual hydraulic circuits (left/right)
The system efficiently manages uneven loads. On Metsjö hooklifts, the left and right sides can also be raised or lowered individually from the driver’s position, enhancing both safety and ease of use.

Because the chassis height can be adjusted via the hydraulic suspension, MetaQ models allow easy body changes: the chassis is raised, support legs are deployed and tipping joints released. The vehicle can then drive under another body, enabling highly efficient use of the chassis for different crops or dump operations.

Proven efficiency: up to 25% lower fuel consumption

Metsjö’s hydraulic suspension is not only stable – it is also highly energy efficient.

An independent study conducted by JTI (Swedish Institute of Agricultural and Environmental Engineering) shows that a Metsjö MetaQ 75 consumes approximately 25% less fuel than a conventional trailer.

Why?
Precise wheel geometry and controlled load distribution minimise energy losses over every metre driven.

50% lower ground pressure – protect yield and soil structure

A study by RISE (Research Institutes of Sweden) confirms the importance of Metsjö’s chassis concept for soil health.

• A fully loaded MetaQ 75 produced approximately 50% lower ground pressure than a conventional trailer

• This despite carrying twice the load

Conclusion:
Chassis design, weight distribution and suspension are at least as important as tyre choice when it comes to reducing subsoil compaction.

Active hydraulic suspension – the best of both worlds

For operators who want both transport comfort and maximum stability, Metsjö offers active hydraulic suspension with accumulator tanks.

• Empty trailer: Accumulators provide soft, compliant ride similar to air suspension

• Heavy load: The system automatically stiffens, delivering uncompromising stability when it matters most

Summary – a long-term investment

Choosing the right suspension is a long-term decision.
Even if the first owner does not intend to operate tall bodies or containers today, future users may – making stable suspension critical for both safety and resale value.

Why choose hydraulic suspension from Metsjö?

• Safety: Active roll stability reduces rollover risk

• Economy: Lower fuel consumption and reduced tyre wear

• Precision: Laser-aligned geometry for perfect tracking

• Functionality: Independent left/right adjustment simplifies daily work and body changes

Want to know which suspension system best suits your operation?
Contact Metsjö for technical advice based on real operating conditions.