A double acting hydraulic cylinder refers to a hydraulic cylinder that can input pressure oil from both sides of the piston. It is often used as the driving component of the jack. The actuator of the double acting hydraulic cylinder is the main output device of the hydraulic motion system. Although it varies in size, type and design structure, this part is usually the most observable part. These actuators convert fluid pressure into rapid, controlled linear motion or force to actuate a load.

 

 

Single acting hydraulic cylinder means that the movement in one direction is realized by oil pressure, and the return is by external force such as self-weight or spring. Only one end of the two chambers of this oil cylinder has oil, and the other end is in contact with air. Double acting hydraulic cylinders have oil in both chambers, and the movements in both directions are realized by oil pressure.

 

 

A typical actuator includes a hydraulic cylinder block, throttle valve cover, piston, piston rod, seals, and bearing surfaces for the piston and piston rod. Generally, it can withstand pressures within 20,000 kPa (continuous pressure) for various links in industry; for stirring and pressure applications, it can reach 55,000 kPa. Its stroke length can reach 3 meters, and the hydraulic cylinder diameter can reach 20cm, and there are larger sizes for other special applications.

 

According to the basic hydraulic relationship (Pascal's law), the linear pressure generated by the cylinder is the product of the system fluid pressure P and the effective area A of the piston, that is, F=PA. Of course, friction and other practical losses reduce the force's effectiveness.

 

The simplest actuator construction is a simple acting hydraulic cylinder with fluid on one side of the piston producing output force and motion in one direction only. Gravity or an external spring returns the piston to its original position and the fluid returns to the cylinder. As the piston rod flexes, a double acting cylinder moves fluid from either end of the piston to generate force or motion. The seal between the outside diameter of the piston and the inside diameter of the cylinder must handle both direction and motion. Also, there could be a double-ended rod cylinder, which adds a piston rod extension movement through the rear cover of the cylinder.

 

In a typical double acting hydraulic cylinder, the force exerted by the piston on extension will be slightly greater than the force on contraction. Although the pressure received on each piston is the same, the force will vary due to the effective area exposed to the hydraulic fluid.

Another alternative type of actuator is a piston-style cylinder, which uses a large-diameter piston rod to adapt to various environments. The full-diameter design of the piston can be used in long-stroke horizontal elements or vertically in pressure or impact environments. Under load, bending of the piston rod is avoided.

 

The piston is connected to a high-strength steel piston rod, and the other end of the piston rod is connected to the piston end. Surface hardening or chrome-plated rods are usually used to make the surface treatment very delicate and ensure long-term use of the sealing effect. The piston must fit precisely to the cylinder, each part is a rigid cylinder and is precisely machined to produce smooth output movement.

 

Double acting cylinders are the most common type of hydraulic cylinder, providing output travel in both directions. Industrial cylinder blocks also support tie rods to hold the cylinder block, cylinder head and end caps.

 

 

The latest industrial double-acting hydraulic cylinders also incorporate sensor feedback and an electro-hydraulic servo valve to enable complex high-speed and displacement control. The scope of application not only includes the production of mechanical machine tools and metal processing equipment, but also can be widely used in steel actuators, nuclear power plant controls, passenger elevators, etc.

 

 

Some advantages of double acting hydraulic cylinders include:

Increased efficiency: Double acting hydraulic cylinders use less hydraulic fluid than single acting hydraulic cylinders, which can lead to increased efficiency and cost savings.

Better control: Because they can extend and retract using hydraulic pressure, double acting hydraulic cylinders offer better control and precision in applications that require precise movement.

Versatility: Double acting hydraulic cylinders can be used in a wider range of applications compared to single acting hydraulic cylinders, making them more versatile.

 

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