Kyntronics Hybrid Electro-Hydraulic Actuators (SHA) Compared to Electro-Mechanical Screw-Type Actuators (EMA)

Ball Screw / Roller Screw Electro-Mechanical Actuators (EMA)

Ball Screw and Roller Screw actuators (EMAs) are a commonly-used linear motion solution. These systems are deployed where precision control is required and often as a replacement for hydraulic cylinders in some higher force applications.

Screw-Type actuators are susceptible to damage from shock loads and premature wear causing unplanned downtime and reliability issues.

Screw-Type EMA Challenges

• Gears, roller and ball screws and other mechanical components wear out from metal-to-metal contact from repetitive concentrated loads.
• Shock loads and Side loading can cause significant damage and premature failure.
• EMAs require regular lubrication and have a finite life (see L10 chart below).
• EMAs require expensive load cells for accurate force control.
• EMAs require a brake to hold position, can be back-driven and have backlash.
• Are large & very costly at higher loads (>5,000lbf).
• Have limited stroke length (24”) without incurring expensive premiums.

Hybrid Electro-Hydraulic Actuator (SHA)

The SHA is an “electric linear actuator” that looks similar to a screw-type actuator but rather than using gears, drive screws and driven nuts, the SHA uses an integral hydraulic cylinder with a minimal amount of fluid and no hoses or leak points.

Compare Hybrid SHAs to EMAs

The SHA combines the Best Features of Screw-Type EMAs and Hydraulic Actuators while Eliminating their Shortcomings

Electro-Mechanical Actuator (EMA)

EMA life span is load dependent. Improving EMA life requires larger and more expensive size screws
EMA metal-to-metal wear further decreases reliability and requires regular lubrication
EMAs are highly susceptible to damage from shock loads and side-loading

Kyntronics Hybrid Electro-Hydraulic Actuator (SHA)

SHA is rated at 50,000,000 inches of travel (before a simple rod seal change) regardless of load
No metal-to-metal contact leads to increased reliability (load independent)
The SHA provides 10X-100X better reliability compared with Ball Screw / Roller Screw Actuators