Use Case: Wheel Loader for Earthworks

Adsorber on Hydraulic Unit

Wheel loaders are exposed to harsh environments on construction sites – they are used in all weathers and must function reliably over long periods. Adsorbers protect the entire hydraulic system of mobile machines and thus ensure long maintenance intervals – even for machines with tank pressures of 0.3 to 0.8 bar.

Need for an adsorber

The high temperature fluctuations and high humidity levels to which wheel loaders are exposed in outdoor applications are a challenge for the hydraulic system. If it heats up during operation and then cools down again, the moisture contained in the air condenses in the hydraulic tank and contaminates the hydraulic oil.

To protect the environment in the event of a leak, biodegradable hydraulic oil is used in wheel loaders. The synthetic esters are highly hydroscopic and attract atmospheric moisture. In the case of the bio-oils, contact with water leads to decomposition and premature aging by hydrolysis.

It is therefore necessary to prevent moisture from entering the tank – an adsorber performs this task by drying the air before it is drawn into a hydraulic tank to balance the volume.

Adsorber on a wheel loader

To permanently protect the wheel loader from moisture, an adsorber is installed. It separates dirt particles as small as 3μm and dries the air completely. To build up the required overpressure in the tank, a valve adapter is also used to keep the pressure constant at 0.5bar.

Test: Wheel loader WITH and WITHOUT adsorber

In order to demonstrate the added value of the adsorber in figures, two identical Hitachi wheel loaders – one WITH and one WITHOUT adsorber – were operated over 5 winter months.

Laboratory report wheel loader WITHOUT adsorber: The water content remains constant at 200 ppm due to the low working hours. In case of larger air movements, moisture would be increasingly sucked in.

Laboratory report wheel loader WITH adsorber: The benefit of the adsorber is already visible after a very short time. After 5 months, the water content drops from 180 ppm to 40 ppm. The reason is the constant drying by diffusion of the desiccant and the strongly dried air flowing in during the working process.

Conclusion: The adsorber reliably protects the wheel loader’s hydraulics from damage caused by water/moisture – even when machines are operated under the toughest conditions and with tank overpressure. The service life of the machine increases and maintenance costs decrease.