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Introduction to 180° Drive Linear Actuators

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Introduction to 180° Drive Linear Actuators

What is an Electric Linear Actuator?

In numerous applications in the medical and industrial fields, linear motion can be required to perform various tasks. An electric linear actuator harnesses the power of electricity and the rotational motion of an electric motor, transforming it into mechanical power and linear motion, respectively.

An electric linear actuator serves as a crucial machine component, commonly employed for straightforward push-and-pull movements but also used in lifting and tilting applications. The significant advantage of electric linear actuators lies in their capability to provide efficient, long-lasting, and sustainable motion control.

Types of Electric Linear Actuator Systems*

1. Lead Screw Mounted on Shaft. In this system, the lead screw is assembled on the motor shaft or gearbox shaft, and the nut is guided in the anti-rotation feature to constrain its rotary motion. When the lead screw rotates, the nut provides the linear motion, traversing back and forth along the lead screw. To achieve the desired linear motion in the application, it is essential to guide the nut at the application level. If the torque and speed requirements are beyond the capability of the motor technology, a gearbox is incorporated into the design.

2. Lead Screw Integrated in Motor for Direct Linear Motion. In this system, the nut is integrated with the rotor of the motor, and the lead screw is carefully guided by an anti-rotation feature. The rotation of the rotor facilitates the linear travel of the lead screw, achieving direct linear motion from this design.

*Linear actuator systems can utilize ball screws or lead screws. This blog focuses on those using lead screws.

Each of the above systems is common and readily available in the market. The selection of the correct type of system is based on the specifications of the actuator system and the application requirements.

What is a 180° Drive Linear Actuator?

This intriguing drive mechanism showcases a unique feature where the output motion is cleverly offset from the motor axis. In simpler terms, the motion generated at the output axis is precisely 180° opposite to the input axis. To better visualize this concept, review the diagram below that illustrates the input and output axes, with power flowing seamlessly from the motor to the lead screw and nut. It's this unique arrangement that makes the 180° Drive Linear Actuator a highly versatile mechanism for a wide range of applications.

Why is a 180° Drive Needed?

For some applications, the above-mentioned types of linear actuator systems are not ideal due to space constraints or packaging requirements; in other cases, the application demands linear motion that is offset to the motor axis, providing the ability for a more ergonomic application design. It’s also possible that standard actuators will not meet the force and speed requirements that the application demands. In that case, the ability to individually select the motor, gearbox, and lead screw for the 180° drive linear system can be a significant advantage.

Components of a 180° Drive Mechanism

This mechanism comprises an electric motor, a feedback system, a gearing system, a lead screw, and a nut. The choice of electric motor technology depends on the specific application requirements (read more on how to select the ideal motor technology here).  Similarly, the appropriate gearing technology can be chosen according to the desired output. The lead screw and nut components have standard configurations available, plus the ability to customize to the specific application demands. 

Potential Configurations for 180° Drive Mechanisms

Figures 5-7 (On Website) show a few potential configurations of the previously mentioned drive components, but these possibilities are not exhaustive. Two primary lead screw arrangements exist: captive and non-captive. In the non-captive arrangement, the anti-rotation feature is provided within the application to achieve linear motion. Conversely, in the captive arrangement, the anti-rotation feature is provided within the actuator itself to achieve linear motion.

Applications Using a 180° Drive Linear Actuator

The 180° drive linear actuator provides advantages in a wide range of applications across medical and industrial devices. For medical, a key application is the syringe drive mechanisms in auto-injectors and on-body injectors, optimizing the device size and ergonomics.  Additional applications like electronic pipettes, prosthetic hands, and surgical staplers can utilize the unique combination of force and speed with the compact size. 

Conclusion

Electric linear actuators play a crucial role in converting the rotational motion of an electric motor into precise linear motion across a wide range of medical and industrial applications. The 180° drive linear actuator, with its unique offset power output, has several potential configurations and is versatile in its output capability. Engineers, equipped with an understanding of these linear actuator systems, can accurately address the complexities of linear motion to devise customized and efficient solutions.