Types of Hydraulic Cylinders: A Comprehensive Guide

For lifting operations, the cylinder is the essential tool. It makes it possible to facilitate the traction of a finally, maintenance, or even the lifting of very heavy loads. There are different types of hydraulic cylinder. Here are what can be found on the market and their specificities to help you choose the one you need!

Construction types of hydraulic cylinders

According to their functioning, the Hydraulic Cylinders are divided into:

•       Single-acting cylinders;

•       Double-acting cylinders.

Single acting cylinders

In single-acting cylinders, the pressurized oil enters only one chamber and can, therefore, control movements only in one direction. Single-acting cylinders can be with plunger piston or spring return.

Plunger piston cylinders- This type of cylinder can only perform a pushing action and, depending on needs, can be equipped with an internal guide piston or not. This type of cylinder is used when the existence of a contrasting force of a certain direction guarantees the return movement to the initial position. Therefore, the exit phase is made possible by the action of the oil pressure on the piston surfaces, while the return phase is guaranteed by the action of an external force.

Spring return cylinders- This type of cylinder is used when there is no external force that guarantees the recall phase. This phase is, therefore, guaranteed by the action of a spring, which, depending on the construction method of the cylinder, can act either during the exit phase of the cylinder piston or in the retraction phase. The opposite phase, i.e., the one in which the cylinder carries out its driving action, is ensured by the action of the pressurized oil.

Double acting cylinders

The double-acting Industrial Hydraulic Cylinder has two opposing useful surfaces of the same or different area and is equipped with two supply connections, which alternatively function, one as a true and proper supply and the other as an exhaust. There are different types of double-acting cylinder:

•       Differential cylinder;

•       Synchronous cylinder;

Differential cylinders- The differential double-acting cylinder has two opposing useful surfaces of different sections and is equipped with two supply connections. By feeding one of the two connections with fluid under pressure, a thrust or traction force is transmitted to the piston and a consequent exit or return motion.

The cylinder is named differential because the two useable parts are distinct, resulting in variable cylinder behavior during the piston exit phase and the re-entry phase.

In the exit phase, since the pressure acts on the larger surface, there will be a greater force than in the re-entry phase; on the contrary, the speed will be greater in the re-entry phase because the same flow rate will act on a smaller surface.

Double Rod Cylinder (Synchronous Cylinder)- The two-rod cylinder is obtained by connecting two rods of the same or different diameter to the piston, however smaller than that of the piston. The maximum force developed in both directions is given by the product of the respective annular areas by the operating pressure.

If the diameters of the two rods are equal, so are the annular areas on the two sides of the piston, so at equal pressure, the forces developed in both directions are equal. Furthermore, since the annular areas are equal, with the same flow rate introduced through connections A and B, equal speeds develop in both directions, hence the name synchronous cylinder.

How Do You Size and Choose A Hydraulic Cylinder?

Two pressure values ​​are indicated for all cylinders:

•       Recommended nominal pressure for good durability;

•       Maximum pressure not to be exceeded.

All components are sized to guarantee a high degree of safety, even at maximum pressure. When choosing the working pressure, it is advisable to focus on the nominal pressure and check that the increases due to braking, sudden impacts, and the like do not lead to pressure increases such as exceeding the maximum value indicated.

Also Read:- Top 5 Hydraulic Cylinder Maintenance Tips for Longevity

The pistons of hydraulic cylinders are subject to peak load. For the buckling load verification, the case of elastic or Hooke-type buckling load is considered, and the cylinder, fully extended, is assimilated to a slender rod of the diameter of the rod.

To determine the free bending length, the geometric length of the member must be multiplied by an appropriate coefficient, which depends on the constraint conditions.

Choosing the right hydraulic cylinder size and pressure is crucial for optimal performance and safety in various applications. When it comes to these components, it's essential to consult reputable hydraulic cylinder manufacturers for guidance and to ensure that your selection aligns with your specific operational requirements.