Electric Cylinders – Linear Motion Powered by Electricity

The term “electric cylinder” is a collective term for all modules that generate linear motion via an electric drive. Electric cylinders are therefore a practical alternative or addition to hydraulic cylinders or pneumatic cylinders. They offer several advantages but cannot replace fluid-driven linear motors in all applications.

Structure of an Electric Cylinder

The term “electric cylinder” merely states that an actuator with linear motion is driven by an electric motor. Three designs have become established for this purpose:

1. Electric Solenoid Actuators: An electric solenoid actuator is an electromagnet with a movable core. When the electromagnet is switched on, the core moves through the center of the coil. Pressure and speed are variable. Electric solenoid actuators have a high response speed. They are primarily used for short working strokes. A popular application for these components is the locking of doors and flaps.
   
   
2. Electric Rack and Pinion Drive: An electric cylinder with a rack and pinion drive consists of an electric motor with an attached gear. This engages with a rack and extends or retracts it depending on the direction of rotation. At the end of the rack, there is a mounting in the form of a thread or an eyelet. A robust housing is required to secure the movement. Rack and pinion electric cylinders are often used for opening and closing hatches, windows, and flaps. Their manufacturing is simple and cost-effective. However, the gearing is a critical point that quickly wears out under overload. Therefore, these types of electric cylinders are mostly used only for light tasks.
   
   
3. Electric Spindle Drive: An electric cylinder with a spindle drive consists of an electric motor that moves a spindle rod. Spindle drives are characterized by consistent force and precision, even over long distances. This makes them very popular in machining technology, for example. Spindle feeds are also found in high-quality 3D printers. In the electric cylinder version, spindle drives are often used in hydraulic-free telescopic booms.
   

Advantages of Electric Cylinders

Electric cylinders are more cost-effective and simpler in design than hydraulic cylinders. They also have no risk of leakage and are therefore very reliable in operation. These components also do not generate high temperatures.

Disadvantages of Electric Cylinders

Electric cylinders are severely limited in their force development. For demanding applications such as presses, excavator arms, or moving heavy masses, they are significantly inferior to hydraulic applications. Furthermore, they are slow, especially compared to pneumatic cylinders. This limits the application of electric cylinders to a few use cases. Finally, electric cylinders always depend on a power supply. If this fails, the actuator can only be adjusted with great effort. For pneumatic or hydraulic cylinders, manual pressure release is available in such cases to return the machine to a safe state.