What Is a Hydraulic Actuator?
A hydraulic actuator is a device that converts the force of hydraulic fluid into mechanical kinetic energy, enabling linear and rotational motions. Linear motion is achieved through hydraulic cylinders, allowing forward and backward movement. For rotational motion, hydraulic motors facilitate rotary applications, while rotary actuators are used for oscillating movements. Compared to pneumatic actuators, hydraulic actuators offer superior output, speed, accuracy, and durability.
Applications of Hydraulic Actuators
Hydraulic actuators are integral to construction machinery like hydraulic excavators and cranes and are also employed in vehicles, aircraft, industrial machinery, and machine tools due to their powerful performance. The hydraulic unit, consisting of a hydraulic pump powered by an engine or electric motor and an oil tank, is the pressure source for hydraulic fluid, driving the actuator. Direction and speed control are managed through valves, making them versatile for various applications.
Principle of Hydraulic Actuators
In a hydraulic system, power is transmitted through hydraulic fluid in a closed circuit. The force generated by a hydraulic cylinder is the product of the pressure and the cylinder’s pressure-receiving area. System design involves determining the desired thrust and accordingly calculating the cylinder’s dimensions or the hydraulic motor’s displacement to achieve the required torque or force.
Types of Hydraulic Actuators
1. Hydraulic Cylinder
Hydraulic cylinders come in single-acting and double-acting types, with single-acting cylinders requiring an external force for return movement, and double-acting cylinders allowing for bidirectional force application. Installation methods vary based on the desired machine movement.
2. Hydraulic Motor
Hydraulic motors, including piston, gear, and vane types, differ in their operational mechanics and applications. Vane motors, for example, are available in single and double vane configurations, affecting torque and rotation angle.
How to Choose a Hydraulic Actuator
Selection of hydraulic actuators depends on required thrust or torque, pressure resistance, and, for cylinders, buckling strength. Hydraulic motors also require consideration of maximum flow rate, with flow control valves adjusting this rate as needed. By combining linear and rotational motions, hydraulic actuators can achieve complex movements.