Understanding the 3 Types of Mechanical Actuators: Pneumatic, Hydraulic and Electric 

Mechanical actuators are mechanisms that use a source of power to achieve physical movement. These are essential and can be found on nearly every automated machine. The three main types of actuators are pneumatic (air pressure), hydraulic (fluid pressure) and electric. 

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Pneumatic Actuators 

Pneumatic actuators use compressed air or pressurized gas to create a controlled movement.  

Pneumatic actuators are a Steven Douglas Corp (SDC) favorite because they are so versatile and can be customized to fit any project. On top of being cost effective, pneumatic actuators are simple to use and are a safe alternative to both electric and hydraulic actuators since they do not require ignition or electricity to operate.  

One disadvantage of the pneumatic actuator is that a compressor must continuously run to maintain operating pressure whether the device is in use or not. 

Hydraulic Actuators

Hydraulic actuators use fluid pressure to facilitate mechanical movement.  

These are used when a considerable amount of power is needed for a machine or system to operate. Most commonly seen in heavy machinery, hydraulic power is controlled by the amount of fluid in a cylinder. Pressure is created by increasing fluid and lessened by decreasing fluid.  

Although hydraulic actuators are useful when high-powered energy is needed, they are volatile in nature and require highly trained mechanics to operate and maintain. 

Electric Actuators

Electric actuators convert energy from an electrical power source into mechanical energy.  

A variety of uses include valve operation, cutting equipment, food and beverage manufacturing, and material handling. They are generally easy to maintain compared to hydraulic and offer a high level of precision. 

Some disadvantages of electrical actuators are they are not suited for all environments and need supervision for overheating tendencies. Taking into consideration their need for constant power, electrical actuators have no fail-safe position if there is a power loss and have an average failure rate that is higher than that of a pneumatic actuator.  

Example of Actuator Use: Gripping 

With many different uses, gripping and manipulating parts are a notable example that SDC has extensive experience in customizing. Grippers are built with actuators, cylinders, magnets or vacuum cups and powered by an electric, pneumatic or hydraulic power source. 

Each actuator has an optimal middle ground where it performs best. This helps our engineers make data-driven decisions when choosing which actuator best suits their project. 

Air Over Oil Gripper

SDC made a custom hydraulic gripper from scratch to fit an exact product. 

The gripper is split into two pieces. One half moves up for loading product then gripper closes and locks around the part for normal operation. SDC included grippers for a series of products and incorporated quick change disconnects. 

An interesting feature of this gripper is the air over oil system. This allows the hydraulic gripper to operate on a common compressed air system with no hydraulic power unit required. 

Advantages & Disadvantages of the Three Main Types of Actuators

Electric

Pneumatic

Hydraulic

Advantages

  • Easy to maintain 
  • High level of precision 
  • Versatile and customizable 
  • Cost-effective 
  • Safe 
  • Very high force/power 

Disadvantages

  • Less cost effective than pneumatic 
  • Strict working environment 
  • No fail-safe position if power is lost 
  • Compressor must run continuously 
  • Volatile nature 
  • Requires highly trained mechanics