Daimler Buses is cutting buses' fuel consumption thanks to electrohydraulic power steering (EHPS). The fully integrated system replaces the conventional power steering pumps used nowadays in all buses with a gross weight of over 7.5 tons.

Thanks to the demand-based actuation of the electric power steering pump, which had previously been powered by the combustion engine, steering assist can in future be used regardless of the engine speed.

As a result of the conveniently positioned component in the vehicle, the unit, consisting of a three-phase current synchronous motor, control unit, high-performance electrical system and hydraulic pump in a single housing, enables simple visual inspections of the power steering fluid reservoir and its fill level. Short hydraulic pipes also make sure system-based friction loss is significantly reduced within the hydraulic circuit. The intelligent control system converts vehicle data to a demand-based actuation of the electrically operated 24 V pump – consequently, it provides the right amount of steering assistance depending on the driving situation. All in all, this adds up to a significant fuel saving.

The system was developed in collaboration with the Engineering Center Steyr GmbH & Co. KG, based in the Austrian town of St. Valentin. The plan is to offer the system for Mercedes-Benz Citaro city buses as optional equipment from mid-2017.