Hydraulic suspension with self-levelling capability is a new option for Hi-Spec trailers and slurry tankers running on two or three axles.

The Sidra system, produced by Italian running gear specialist FAD Assali, is said to offer a smoother ride for big machines of this type.

It imposes fewer stresses and strains on the tractor, and encouraging faster working speeds.

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A lifting front axle is an option to reduce tyre wear when running empty, along with electronic axle steering.

This can be applied to the rear axle on a tandem, to the front and rear axles on a tridem installations, and even to all three axles with a crab-steer function to distribute the load over a larger surface area.

Digestate tanker

Hi-Spec says a typical unit that would benefit from a Sidra installation is the 5000 TRI SR.

This is a triple-axle slurry and digestate tanker with a capacity of 22,700 litres and one of the largest produced by the Northern Irish firm.

Variants include a semi-recessed chassis to lower overall height for added stability when operating on the 710/50 R26.5 tyres fitted as standard.

Normally equipped with commercial multi-leaf steel spring suspension, the Sidra option has three sets of bolt-on assemblies comprising a central axle, two L-shaped trailing arms carrying fixed or steerable braked hubs and a pair of hydraulic cylinders.

These are interconnected to provide a co-ordinated response to individual wheels dipping into a hollow or riding over a hump.

Hi-Spec credits the optional electronic steering system, regulated through an isobus terminal, as being simpler, neater and more controllable than a hydraulic forced setup.

Sensors on the axles monitor wheel angle and whether the tanker is moving forwards or backwards, with a gyroscope detecting any changes in orientation.

Each axle can be controlled automatically or manually, with a speed trigger engaging auto lock-out on the road.