Linear actuators are used to move a variety of different loads. They convert energy into linear motion and can be powered by pressurized fluid or electricity. In this post, we will break down the key advantages and disadvantages of hydraulic, pneumatic and electric linear actuators.
Hydraulic Linear Actuators
Hydraulic linear actuators utilize a piston-cylinder configuration. An incompressible liquid from a pump moves the piston inside the cylinder. With increased pressure, the piston moves linearly inside the cylinder creating a linear force. The piston returns to its retracted position by either a spring-back force or fluid being supplied to the opposite side.
Advantages
- Hydraulic actuators can hold a constant force without the pump supplying more fluid due to the use of an incompressible fluid.
- Hydraulic actuators can produce very high forces.
- It can produce high speeds.
Disadvantages
- Hydraulic fluid leak which leads to losses in efficiency. This can also lead to cleanliness issues.
- Require many accompanying components including a fluid reservoir, pumps, motors, release valves, heat exchangers, and noise reduction equipment.
- High maintenance systems. Many components to constantly monitor.
Pneumatic Linear Actuators
Pneumatic actuators function in a similar way to hydraulic actuators with the difference being the driving fluid, air rather than hydraulic fluid. The gas is compressed in a piston-cylinder setup which creates a linear force.
Advantages
- Pneumatic actuators are very simple, most aluminum cylinders have optimal maximum pressure ratings which allows for an optimal range of forces.
- Pneumatic actuators are often used in areas of extreme temperatures due to the safety of using air rather than hazardous chemicals or electricity.
- It is a low-cost option.
Disadvantages
- Pressure losses and the compressibility of air make pneumatic devices less capable than other linear motion methods. A compressor must run continuously to maintain operating pressure even if there is no movement needed.
- Pneumatic actuators must be sized for a specific job in order to be efficient. This requires proportional sized valves, regulators and compressors which raises the cost and complexity.
- The air can be contaminated by oil or lubrication, leading to downtime and maintenance.
Electric Linear Actuators
Electric linear actuators convert rotational motion into linear motion. Rotational motion is first generated by the electric motor. This high-speed rotational motion is then reduced by the gearbox to increase the torque that will be used to turn the lead screw. The turning of the lead screw results in linear motion of the acme drive nut. Think of it like driving a screw into a piece of wood, but rather than the screw moving towards the wood, the wood will be moving towards or away from the screw depending on the direction of rotation.
Advantages
- Electric actuators offer the highest precision-control positioning.
- Scalable for any purpose or force requirement.
- They can be easily networked and programmed quickly. Immediate feedback for diagnostics and maintenance is available.
- They provide complete control of motion, offering custom speeds, stroke lengths, and applied forces.
- They are quieter than pneumatic and hydraulic actuators.
Disadvantages
- The initial cost is greater than that of pneumatic and hydraulic actuators.
- They are not suitable for all conditions, whereas a pneumatic actuator is safe in hazardous and flammable areas.
- The electric motors can be large.
All three technologies have their place in the industry, but the flexibility of electric linear actuators, coupled with the fact that the price of electric components has been steadily decreasing over the years, makes them a more popular choice than they once were. Knowing what actuator is best for your application depends on your working environment.
If you require further assistance on selecting the right electric linear actuator for your application, give us a call at 1-800-676-6123, or email us at sales@progressiveautomations.com.