On a conventional truck or bus the hydraulic power assistance for the steering comes from an IC engine-driven pump following the engine speed. This is also the case in many off-highway applications. Typically the pump is dimensioned to give full power steering function already at idle speed of the IC engine. The pump is constantly running and consuming power from the engine. In a hybrid application where the vehicle can operate in pure electric mode, the conventional power steering system cannot be used since the IC engine is turned off during the electric mode. However, using Concentric’s EHS (Electro-Hydraulic System) system, the unit only provides the required power on demand and can still operate during the electric mode for hybrid applications.
The primary benefit of the EHS system is reduced energy consumption, achieving up to 50% in certain applications. It also fits very well into hybrid vehicles where conventional systems cannot be used. The EHS system is typically placed close to the steering gear which also means reduced installation costs.