Electro-hydraulic system is a combination of actuators and a self-contained power unit to provide operation and control with the external electrical power source only. The electrical power supplied is used to energise a motor that runs a hydraulic pump which then supplies the pressurized fluid to operate a hydraulic actuator which controls the valve.
Electro-hydraulic actuators (EHAs), replace hydraulic systems with self-contained actuators operated solely by electrical power. EHAs eliminate the need for separate hydraulic pumps and tubing because they include their own pump, simplifying system architectures and improving safety and reliability. This technology originally was developed for the aerospace industry but has since expanded into many other industries where hydraulic power is commonly used.
With an EHA, high-power versions of these motors are used to drive a reversible pump, which is tied to a hydraulic cylinder. The pump pressurizes a working fluid, typically hydraulic oil, directly raising the pressure in the cylinder, and causing it to move. The entire system, consisting of the pump, the cylinder, and a reservoir of hydraulic fluid, is packaged into a single self-contained unit.
The advantages of the Electro-hydraulic actuators are, it is clean, versatile and have relatively low lifecycle costs. It also matches hydraulic actuators in terms of handling loads and shocks. Electro-hydraulics are now used in a range of heavy load-handling applications in outdoor equipment, marine, military, aerospace, and many other fields.