Mechanical Actuator : Design, Working & Its Applications

In electrical machines, an actuator is an essential component used to move & control a system or device. An actuator uses an energy source and also a control device. Generally, the control device is a valve. Once a control device gets a control signal then an actuator immediately reacts by simply changing the energy source into mechanical motion. There are different types of actuators available like soft, hydraulic, pneumatic, electric, thermal/magnetic, and mechanical actuators. So this article discusses one of the types of actuators namely mechanical actuators – working with applications.

What is a Mechanical Actuator?

The mechanical actuator is a device that uses a power source to attain physical movement. These actuators are important & available nearly on each automated machine. The power sources used in these actuators are; electric current, pneumatic & hydraulic which are operated manually or turned ON/OFF through an automated system. The mechanical actuator’s function is to change the motion from rotary to linear with the help of gearing at a different speed. Mechanical actuators are categorized as lead screws, Ball screws, rack & pinion, belt driven, etc. The mechanical actuator diagram is shown below.

Mechanical Actuator Working Principle

The working principle of a mechanical actuator is to perform the movement by changing rotary motion into linear motion. So the mechanical actuator operation mainly depends on structural component combinations like rails & gears, or chains & pulleys.

Mechanical Actuator Design

The mechanical actuator is designed by using various components but the most activating components are the Motor, Gearing, Screw assembly & Extension tube. These actuators normally work by changing the motion from rotary to linear.

Motor

The motor used in this actuator is a DC motor where all of the actuator’s power is produced.

Gearing

A gearing is designed with plastic or steel which is used to change the relationship between the driving mechanism’s speed & the driven parts’ speed. The gearing is connected simply to a power source like the motor.

Screw

This actuator works on the screw. So by turning the nut of an actuator, the screw shaft will move within a line.

Extension Tube

The extension tube is also called an inner tube which is generally made with stainless steel or aluminum. This tube is connected to the threaded drive nut & extends and retracts once the nut turns along the rotary spindle.

Once the motor in the actuator is powered, then it rotates the gearing. So this gearing simply multiplies the torque & decreases the motor speed. The gears rotate a screw and the nut on the screw is simply connected to the extension tube & is moved in or out based on the screw’s direction is turned.

There is a wrap spring break in several actuators that will hold the load once the motor is not working. This wrap spring break will hold the load in any direction by pushing or pulling without power. The screws used in different actuators are lead screws or ball screws.

Mechanical Actuator Types

There are three types of mechanical actuators available in the market pneumatic or air pressure, hydraulic or fluid pressure & electric actuators.

Pneumatic Actuators

A pneumatic actuator uses pressurized gas or compressed air to form a controlled movement. These actuators are versatile &can be modified to use in any project. The main advantage of this actuator is; it is very simple to utilize and is a secure alternative to both hydraulic & electric actuators as they do not need electricity or ignition to operate. The main drawback of this actuator is that a compressor should run continuously to maintain working pressure whether the device is used or not.

Hydraulic Actuator

A hydraulic mechanical actuator uses liquid pressure to make a mechanical movement. So these actuators are mainly used whenever a significant amount of power is required for a system or machine to function. These are commonly available in heavy machinery where hydraulic power is simply controlled through the amount of liquid within a cylinder. When the fluid is increased then pressure is created and pressure is decreased through decreasing fluid. Even though these actuators are very helpful once high-powered energy is required, they are volatile within nature & need extremely trained mechanics to operate & maintain.  To know more about Hydraulic Actuator.

Electric Actuator

An electric actuator is used to change the energy from electrical to mechanical from an electrical power source. An electric actuator is used for valve operation, food & beverage manufacturing, material handling & cutting equipment. Generally, these are very easy to maintain as compared to hydraulic actuator & provides a high range of precision. Please refer to this link to know more about Electic Actuator.

The main drawbacks of these actuators are; they are not suitable for all environments & require control for overheating tendencies. These actuators have no reliable position if there is a loss of power & have an average rate of failure that is higher as compared to the pneumatic actuator.

Properties

The properties of the pneumatic and electric actuators are listed below.

Advantages and Disadvantages

The advantages of mechanical actuators include the following.

• These actuators are very easy to use.
• The precision level is high.
• These are cost-effective.
• These are versatile & customizable.
• These are very secure.
• Its performance is long-lasting.
• Extended reliability
• Easy setup & installation
• Motion control is more accurate.
• Less noise.
• Less maintenance.
• Energy consumption is less.
• No leaks and a complete range of sizes, options & configurations.

The disadvantages of mechanical actuators include the following.

• Compared to pneumatic, the electrical actuator is less cost-effective.
• Severe working environment
• If power is lost then there is no fail-safe position.
• In a pneumatic actuator, the compressor should run constantly
• Hydraulic actuators have unstable nature.
• Hydraulic actuators need extremely trained mechanics.
• These are very sensitive to vibration

Applications

The applications of mechanical actuators include the following.

• The mechanical actuators are used to change the rotating movement to the linear movement.
• These are applicable where linear movements are required like elevation, translation & linear positioning.
• This actuator simply works by changing one kind of motion into another by using pulleys, gears, chains, etc.
• These actuators change the electrical i/p signal to a mechanical excitation force. These are used in combination with a separate radiator within distributed mode loudspeakers & active control applications for vibration & noise cancellation.
• These devices simply provide limited & controlled movements which are functioned manually, electrically, or with different fluids like hydraulic, air, etc.

Thus, this is an overview of a mechanical actuator – working with applications. In this actuator, the inside mechanisms which are used for converting the i/p power to a motion mainly differ based on the intended output direction & the particular power source utilized. The direction of the o/p motion is either rotary or linear. Generally, these actuators are very powerful as compared to electromagnetic types so used in high-torque applications. Here is a question for you, what is an actuator?