I. Differences Between Electric Push Rods and Electric Cylinders
Both electric push rods and electric cylinders, collectively referred to as electric linear actuators, function through an electric motor driving various screws to rotate, thus converting the rotation of the nut into a linear reciprocating motion.
Essentially, the principles of electric cylinders and electric push rods are the same, both facilitating linear pushing, pulling, and lifting actions.
However, there are nuanced differences between the two (which are both generally termed “electric linear actuator” in English, with no special distinction made between them).
Push Rods: They offer lower thrust, provide simple push-pull action (without any positioning function), and are not designed for high speeds. They usually employ DC motors, with plastic gears in smaller push rods and worm gears in high-thrust push rods.
Servo Electric Cylinders: They are capable of precise positioning, can use either DC or AC motors, offer a wide range of thrust, and typically use transmission belts and directly connected couplings. These cylinders boast a longer lifespan and multiple control modes (speed mode, position mode, torque mode) depending on the requirements.
A detailed comparison of the differences between electric cylinders and electric push rods is as follows:
- Structure: An electric push rod features a standard nut inside and has a larger internal structural gap. It often uses AC or DC motors, resulting in lower repeated positioning accuracy and a shorter lifespan. Conversely, an electric cylinder has a screw structure, typically uses servo motors or stepper motors, and almost zero internal clearance, resulting in high repeated positioning accuracy, broader applications, and a longer lifespan (the total travel can reach over 100,000KM).
- Accuracy: AC electric push rod accuracy: 0.2mm; DC electric push rod accuracy: 1-2mm; Electric cylinder accuracy: 0.01-0.02mm.
- Material Selection: Electric push rods are made with standard trapezoidal screws or ball screws and are usually connected to a gear motor or turbine rod, resulting in lower efficiency. Servo electric cylinders often use ground ball screws or planetary ball screws, and they directly couple with the motor or synchronize with the pulley, leading to very high speed efficiency.
- Speed: Electric push rods typically operate at speeds <100mm/s, while electric cylinders can reach speeds up to 2m/s.
- Control: Electric push rods can only control the 0-point and the end point of the stroke, while electric cylinders can start and stop at any position.
- Thrust: Electric push rods primarily facilitate push-pull actions, with the thrust hardly exceeding 10 tons. Electric cylinders, like servo electric cylinders, can reach a thrust of 35 tons or more.
In summary, electric push rods are simple in structure, offer lower thrust and duty cycle, and have simple control procedures and a lower cost. They are used as actuators in various simple or complex process flows.
Electric cylinders, especially servo electric cylinders, generally offer high thrust, long travel, precise speed and position control, high speed, and cost more than push rods. They are widely used.
II. Which is Better: Electric Push Rod or Electric Cylinder?
Simply put, electric cylinders (generally referring to servo electric cylinders) offer precise positioning, fast speed, large load, and long lifespan, and are often used in industrial equipment and the aerospace field, thus belonging to a different category than electric push rods.
Electric push rods can merely extend or retract, cannot position, and cannot bear large thrust. Smaller push rods often use plastic gears and are typically used in equipment or devices with lower requirements.
For industrial equipment with high requirements, it’s more suitable to use electric cylinders. If it’s for consumer products or equipment with lower requirements, electric push rods can be used.