What are Actuators: Types, Principles, and Applications

What is an actuator, and why is it critical to so many applications, systems, and processes? In very simple terms, an actuator is a device that makes something move or operate. From automatically opening doors at grocery stores to moving a car seat forward and backward, we encounter actuators every day. An actuator converts a source of energy into a physical, mechanical motion. This incoming energy or force can be electric, pneumatic (air), or hydraulic (water). When activated by energy, the resulting motion can be linear or rotary.

Actuators play a critical role in controlling and automating various processes and systems. These devices are widely used in many industries, including manufacturing, robotics, aerospace, and military/defense. The many different types of actuators can be classified by motion or by energy source.

Actuators can be classified by two types of motion: rotary or linear. While both types create movement, they differ in their applications, so let’s review each to get a better idea of their working principles.

Rotary actuators produce a rotational motion by rotating objects around an axis in either a clockwise or counterclockwise direction. They typically consist of a housing that encases and protects the internal mechanisms; an output shaft, where the rotating part connects to the machinery or system being operated; and internal components (e.g., gears, pistons, or vanes) that convert the energy source into rotational movement. Rotary actuators are used in medical equipment, radar and monitoring systems, robotics, the semiconductor industry, special machine manufacturing, and more.

Linear actuators produce linear motion, moving objects along a straight path. Depending on the type of energy applied, linear actuators create this motion through mechanisms such as a belt and pulley, rack and pinion, or ball screw. They often incorporate limit switches or sensors that control the range of movement by stopping the actuator at predefined positions. Linear actuators are known for their high repeatability and positioning accuracy and are commonly used in industries such as food processing, automotive, and material handling for tasks like pushing, pulling, lifting, and positioning.

Actuators can be powered by different energy sources, including (but not limited to) electricity, water pressure, or air pressure. Each energy source significantly affects the actuator's design and functionality, offering unique advantages depending on the application.

Hydraulic actuators use fluid pressure to generate motion, typically employing cylinders or pistons to move loads.

These types of actuators use compressed air to produce motion by typically employing cylinders or rotary actuators. 

As the name implies, these actuators use electrical energy to generate motion. These types of electric actuators can operate with AC or DC power supplies.

These two types of actuators use magnetic and temperature changes to produce motion. Magnetic actuators use magnetic fields to generate force, whereas thermal actuators use the expansion or contraction of materials in response to temperature changes.

These types of actuators employ physical mechanisms like levers, gears, or cams for generating motion.

Actuators are indispensable because any mechanical movement requires them, and most devices require some form of mechanical movement. However, not all actuators are created equal - meaning different types of actuators are better suited for specific roles. Following are some real-world applications of actuators in industry.

Hydraulic actuators (linear) are used in the landing gear of commercial and military aircraft to extend and retract the gear during takeoff and landing. The hydraulic system provides the necessary force to handle heavy loads and operate reliably under various conditions.

Missile launching systems use linear pneumatic actuators to control hatches, valves, and other components in the launching mechanism offering quick response times and reliability when controlling moving parts in mission-critical applications.

Mechanical rotational actuators are instrumental to manual override systems associated with industrial electronics control panels. In cases where electronic control fails, these actuators allow operators to manually engage or disengage machinery, ensuring continuity.

How do you know what type of actuator best fits an application? There are several factors to consider to ensure optimal performance, efficiency, and reliability when selecting an actuator for a specific application.

Begin with the type of motion required: linear or rational. Next, evaluate how much force or torque is necessary to move the load. Also, evaluate the speed requirements by determining how fast the actuator needs to move. Finally, determine the precision requirements by assessing how precise positioning or control needs to be for optimal performance.

The operating environment is critical to actuator selection. Will the device be exposed to extreme temperatures, moisture, dust, or corrosive substances? For example, actuators used in industrial or rugged environments should be rated for protection, while those used indoors in labs or workshops may require less protection. Also, the space constraints are important, including how much installation space is available, the size, and the mounting options.

Based on the application and environmental requirements gathered, compare the different characteristics, advantages, and disadvantages of each actuator type to narrow the selection. 

Electric Actuators 

Ideal for applications requiring precise control, energy efficiency, and automation, such as robotics, electronics, and valve control. 

Hydraulic Actuators 

Suitable for heavy-duty applications with high force requirements, like construction machinery or aircraft systems.

Pneumatic Actuators

Best for fast, repetitive operations that require quick actuation yet moderate force, like in automation systems and light industrial applications.

Thermal or Magnetic Actuators

Best for specialized applications where passive operation based on environmental conditions (like temperature) is necessary.

Mechanical Actuators

Most common with applications where low cost, simple operation, and durability are important (ex: manual valve systems or mechanical locks).

Once an actuator type is selected, it’s always best practice to test prototypes or conduct simulations to verify the actuator’s suitability for the application.

Given the vast array of actuator applications available, connection methods and degrees of complexity will vary between different types of actuators. Linear electric actuators, however, are very common and relatively simple to connect. These actuators often come with four pins, which makes their connection as simple as plugging them in. If the actuator does not have four pins, the process is more involved and requires an additional connector. 

Next, connect the actuator to the 4-pin connector by twisting the corresponding exposed wires together by color, usually blue and brown, and covering the connection with electrical tape. You may need to strip the wires if not enough is exposed for connecting. If the wire colors differ between the connector and actuator, use the following guidelines: 

• With red and black wires, connect the red to the brown wire of the actuator and the black wire to the blue. 
• With red and blue wires, connect the red to the brown and blue to the blue wire on the connector. 
• With red and yellow wires, connect the red to the brown wire and the yellow to the blue wire. 

Next, connect to the power source. If any issues arise, refer to the manufacturer's specs for troubleshooting.

The two most common options for mounting linear electrical actuators are stationary and dual pivot. Following are some basic guidelines for each mounting type:

With a stationary mount, one end of the actuator is fixed to a stationary structure, allowing extensions and retraction without rotating, which is ideal for linear movement. Begin by choosing the stationary mounting point for the base of the actuator and the attachment point for the rod end, and ensure the points are directly aligned with the actuator’s axis of motion to prevent lateral forces. Next, attach the mounting bracket to the base of the actuator, followed by mounting the bracket to a stationary structure, such as a wall or frame. The mount should be secure and rigid enough to handle the forces generated by the actuator. 

Now, attach the rod end of the actuator to the load, i.e., the part being moved, using a bracket or a direct connection, depending on the application. Always ensure the rod end attachment is aligned and does not interfere with the actuator's linear motion, manually extending and retracting the actuator to verify that it moves smoothly without side loading or bending. Verify everything is securely attached and test the actuator movement across the full range by powering the actuator. It should move smoothly without straining the motor or attachments.

With a dual pivot mount, the actuator is free to pivot at both ends, which is ideal for situations requiring dynamic motion. Begin by selecting the pivot points, one at the actuator's base (near the motor) and one at the rod end. They should align to allow smooth movement of the actuator without binding. Next, attach a pivot bracket to the base of the actuator. Ensure it is securely mounted to the stationary structure where the actuator will be fixed, and the bracket allows for free rotation of the actuator base. Then, attach the second pivot bracket to the load or the part being moved by the actuator so the rod end fits securely into the bracket, allowing it to pivot freely as it moves in and out. 

Test the attachments by manually extending the actuator and tightening attachments as needed. When ready, connect the actuator to a power source and test its action, ensuring that no parts are obstructing the motion and both pivots are rotating freely.

As a full-service, authorized stocking distributor for leading manufacturers, you can find an array of actuators at Peerless Electronics. We carry a range of types and sizes to complement applications across industries, from simple switches to complex robotics. In addition, all Peerless component purchases are supported by over 50+ Value Added Services, including 24/7 technical support. Don’t see what you need in stock? https://peerlesselectronics.com/contact-us for help.

What is an actuator system?

Actuators convert energy sources into mechanical motion, allowing systems to perform tasks like opening/closing valves, moving loads, or adjusting positioning.

What could cause actuators to fail prematurely?

Several scenarios can cause premature failure, including overloading, poor alignment, lack of lubrication, contamination, excessive heat, or electrical issues like power surges or improper voltage.

Can actuators be repaired?

Common actuator repairs can include replacing motors, gears, or electrical components. However, severe mechanical damage will likely require actuator replacement.

How to test if an actuator is working?

Testing is as simple as applying power and checking for movement. If the actuator doesn’t move after applying a power source, then check electrical connections, measure voltage, and listen for unusual noises. Manually moving the actuator can also help detect mechanical issues like jamming.