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 include:

• Gears, roller and ball screws, and other mechanical components wear out due to 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, otherwise can be back-driven and have backlash.
• They are large & very costly at higher loads (>5,000lbf).
• Have limited stroke length (24”) without incurring expensive premiums.

Kyntronics Hybrid Electro-Hydraulic Actuator (SHA)

The SHA is an “electric linear actuator” that resembles a screw-type actuator. However, instead of using gears, drive screws, and driven nuts, the SHA utilizes an integral hydraulic cylinder with a minimal amount of fluid and there are no hoses or leak points. 

Read Kyntronics’ Insights: ELECTRO-MECHANICAL ACTUATORS (EMAs) AND KYNTRONICS ACTUATORS: SIMILARITIES AND DIFFERENCES

Electro-Mechanical Actuator (EMA)

• EMA life span is load-dependent. Improving EMA life requires larger and more expensive 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