Electrohydrostatic Actuator vs. Conventional Hydraulic Cylinder Systems: OEM Guide

“Electrohydrostatic actuator vs. hydraulic cylinder” is not a like-for-like component comparison. An electrohydrostatic actuator (EHA) is an actuator system architecture that can include an electric motor, a pump, a hydraulic manifold and a cylinder. A conventional hydraulic cylinder is one component in a larger circuit, commonly supplied by a hydraulic power unit (HPU), valves, piping and controls.

The right comparison is therefore between complete motion systems: an integrated, locally controlled electrohydrostatic package and a conventional centralized hydraulic supply feeding one or more cylinders. The appropriate choice depends on force and speed requirements, duty cycle, machine layout, control strategy, maintenance capability and lifecycle costs.

How the architectures differ

In a conventional arrangement, the cylinder receives pressurized fluid through a hydraulic circuit. Pump, reservoir, valves, lines and control hardware may be shared with other functions. This can suit machines where centralized power is already present or several actuators need a common supply.

In an EHA, an electric motor drives a local pump that moves fluid to and from the actuator. Moog’s Compact EAS is one vendor example of an integrated assembly containing a servo motor, internal gear pump, manifold and cylinder; its published description states that the system can operate without an external power pack or tank. That is a specific product architecture, not a universal definition of all EHAs. Moog Compact EAS overview.

Practical selection trade-offs

• Machine layout: a decentralized actuator can reduce long hydraulic runs in some layouts; it also places motor, pump and controls near the moving function, where space, cooling and service access must be checked.
• Shared power demand: a central HPU may serve multiple functions, while an EHA packages power generation locally. Compare simultaneous duty cycles and peak demand rather than comparing nominal component ratings.
• Control: define required position, speed, force or pressure behavior, feedback devices, fault handling and safety functions. Do not assume an actuator package automatically meets the machine’s safety requirements.
• Maintenance: centralized systems may be familiar to a plant’s hydraulic team; integrated packages can simplify some connections but require support for their electrical drive, pump and control components.
• Environment: temperature, contamination, vibration, ingress protection, noise and heat rejection affect both architectures. Review the complete installed system, not just the cylinder.
• Lifecycle: include installation, electrical supply, commissioning, fluid management, spare parts, service skills, downtime and energy profile in the comparison.

When the conventional cylinder remains the right choice

A conventional cylinder can remain the straightforward option when a suitable HPU and valve system already exist, several actuators share a hydraulic supply, cylinder replacement is the primary need, or the application is already engineered around a conventional circuit. Cylinder selection still requires verified force, pressure, stroke, mounting, speed, side-load and environmental requirements.

When an EHA deserves an engineering study

Evaluate an EHA when decentralized motion, reduced external piping, controllable motion profiles or machine modularity could benefit the design. Then confirm that the package’s force and stroke envelope, dynamic duty, thermal limits, feedback, electrical supply and service model match the real machine. Request supplier data for the exact configuration; broad claims about efficiency, oil volume or maintenance should not be applied to a different design without supporting calculations.

A fair comparison checklist

• Compare complete bills of material and installation scope, not an EHA package against a cylinder-only price.
• Use the same load cases, motion profile, duty cycle and environmental assumptions.
• Document the control interfaces, feedback, stopping behavior and fault response.
• Check service access, fluid containment, thermal management and spare-part availability.
• Have machine-level safety functions assessed separately under the applicable design process.

Zhenqiang’s site focuses on hydraulic cylinders rather than claiming to supply a complete electrohydrostatic drive. If your design requires a cylinder component, review custom cylinder options. Explore more engineering topics in the Trung tâm Tri thức or visit the home page.

Frequently asked questions

Is an EHA a special kind of hydraulic cylinder?

No. It is a system that can incorporate a cylinder alongside a motor, pump and other components. The cylinder remains an actuator component within that architecture.

Does an EHA always eliminate the hydraulic power unit?

No universal rule applies. Some integrated closed-circuit designs are specified to operate without an external HPU, while other electrohydraulic systems use different layouts. Check the exact supplier architecture.

Can the two approaches be compared on energy use alone?

No. Energy depends on the motion profile, loading, control strategy, pump and motor selection, standby behavior, thermal losses and the rest of the machine.