Episode # 67: What is a Hydraulic Actuator?

What is a Hydraulic Actuator?

• Not much different than pneumatic actuators as discussed in Episode 66.
• Basic motion actuation for fluid power
• Key differences
  • Pneumatics use air. Hydraulics use liquid.
    • Devon Hyatt, specialist in fluid power, expands on the differences
• Air is compressible.  Liquids are not.
• Results in higher forces from hydraulics
  • Do hydraulic actuators also have single-acting and double-acting options?
    • Yes, Devon Hyatt explains further.
  • Do hydraulic actuator types also include rod, rod-less, rotary and gripper?
    • Devon explains that, while there isn’t really a rod-less type, there are many different types
  • Are there also ISO and NFPA versions of hydraulic actuators?
    • Yes
  • What are open versus closed-loop hydraulic systems?
    • Open-loop systems take liquid from and return it to a reservoir with a breather
    • Closed-loop systems uses a recirculation pump instead while containing the liquid entirely within it and the hoses going to the actuator
• When would I use hydraulics over pneumatics?
  • To insure constant force
  • To produce higher forces
  • To absorb higher vibration or shock loads
• System Components needed to move a hydraulic actuator
  • Provide liquid flow
    • Engine or motor plus a pump
  • Control the liquid to the actuators
    • Valves and flow controls
  • Make sure the liquid is clean
    • Filter and regulate
• Pros of hydraulic actuators
  • High force-to-size ratio
  • Shock absorbent
  • Great for mobile equipment
  • Simplicity
• Cons of hydraulic actuators
  • Components wear out making for short life cycles
  • Fluid quality maintenance
  • Low efficiency
  • Leaks are messy
  • Low accuracy
  • Limited cylinder positions

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