You are currently viewing Hydraulic Cylinders | Design | Working | Types
Section view of a hydraulic piston.

Hydraulic Cylinders | Design | Working | Types

A hydraulic cylinder, which is also known as a linear hydraulic motor is a mechanical actuator (which means it helps a machine or a device in its operation) that is used to give a force that is unidirectional through a unidirectional stroke.

In other words, it can also be said that a hydraulic cylinder is used for the conversion of energy stored in the hydraulic fluid into a force that is used to create the movement of the cylinder in a linear direction.

It has a lot of uses, notably in construction equipment such as in engineering vehicles, machinery used for manufacturing, and civil engineering.

Design And Working Of Hydraulic Cylinder

The working principle of the hydraulic cylinder is Pascal’s law which simply says that in a fluid at rest in some container that is closed, a  change in pressure in one part is transmitted without any loss to every portion of the fluid and even to the walls of the container.

The larger the size of the cylinder, the greater will be the force generated. The diameter of the piston is called the bore. A piston is situated inside the cylinder for some pushing fluids. So, if seen from the perspective of Pascal’s principle, larger bore cylinders will have a higher capacity for lifting.

Hydraulic cylinder design typically consists of two cylinders having different diameters which are connected parallel to a pipe. The cylinders have two separate ports for the intake and the removal of fluid. This assembly is then filled partially using a suitable hydraulic oil that is not compressible.

A piston appears as a flat solid disk that has a rod attached to its center. While the force is applied to the smaller piston, it will try to compress the fluid present in the smaller cylinder. This will lead to the flow of fluid from a smaller cylinder to the larger cylinder through the tube connected and then the piston of the larger cylinder will move up due to this generated force.

The key factor that makes the piston move is the pressure difference generated inside the cylinder. When a  continuous pressure is applied and the cylinder reaches its maximum space, the pressure release valve will relieve the pressure generated and will make it possible to move further.

Classification Of Hydraulic Cylinders

1. According To Function

  • Single Acting Cylinders:

In single-acting cylinders, the fluid receives pressure from one side of the cylinder only, even during both the expansion as well as the retraction process. A spring or an external load is used to return the cylinder top to its original position which is referred to as the position when the pressure of the fluid is cut off.

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  • Double Acting Cylinders

In the double-acting cylinders, the fluid is pressurized from both directions. Single cylinders containing springs are not used in large stroke applications since they consist of some inherent mechanical problems associated with the spring. The double-acting rods could be of two types:

  • Single rod ended
  • Double rod ended
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2. According To Specifications

  • Plunger Cylinders:

Plunger cylinders are also named Ram cylinders. These types of hydraulic cylinders are usually placed in an upright position. This is done as once the supply of the fluid gets stopped, the weight on the cylinder will make it return to its original position. The cylinders which are used in automobile service centers are a nice example of plunger cylinders.

Image result for plunger hydraulic cylinder
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  • Telescoping Cylinders

Telescopic cylinders usually have a maximum of six stages and are especially used in applications that have less area. Telescopic cylinders could either be single-action cylinders or double-action ones. These cylinders often have a long stroke and are very helpful in some applications such as cranes and forklifts, etc.

Image result for telescoping hydraulic cylinder
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  • Cable Cylinders

The cable cylinders could either be hydraulic or even pneumatic powered cylinders that are typical of the double-acting type. The strokes of these cylinders are mainly long and they produce moderate force. The cable cylinders are operated only in a limited space.

  • Diaphragm Cylinders

Image result for diaphragm hydraulic cylinders
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Diaphragm cylinders are of two kinds- flat diaphragm cylinders and rolling diaphragm cylinders. These cylinders have zero leakage around the piston area.

Advantages Of Hydraulic Cylinders:

  • Due to the combination of hydraulic oil and servo valves, hydraulic cylinders can repeatedly hit targets within a small range. So, they are very accurate and precise.
  • The speed of hydraulic cylinders is independent of the mechanisms of operation, so it is not affected by the weight of the load like the electronic systems.
  • Hydraulic cylinders can produce a very large amount of force despite their small size. So, the user does not need to worry about any kind of support.
  • Little power is required to operate the mechanisms used by hydraulic cylinders which helps conserve energy and save money.
  • Hydraulic cylinders are very reliable, even when the weather is harsh.

Disadvantages Of Hydraulic Cylinders:

  • The Efficiency of a hydraulic cylinder is a little bit lower than the efficiency of mechanical and electric transfers, and during the regulation process, it is reduced further.
  • Conditions of operation of a hydraulic cylinder such as temperature have a great influence on its characteristics.
  • Efficiency of a hydraulic cylinder is reduced a little in the process of exhaustion of its resource mainly due to the increase in backlashes and the increase of outflow of the liquid

1. What Are The Different Types Of Hydraulic Cylinders?

4 Types Of Hydraulic Cylinder To Consider
  • 1) Single Acting Cylinders.
  • 2) Double Acting Cylinder.
  • 3) Tandem Hydraulic Cylinders.
  • 4) Telescopic/Multistage/Ram type/Actuating Hydraulic Cylinders.
  • Choose The Right Kind Of Cylinder For Your Application.

2. What Are Hydraulic Cylinders Used For?

Hydraulic cylinders are used for creating mechanical force in a linear motion. A hydraulic cylinder is a tube capped at either end with a rod sticking out of one side. Attached to the rod, interior to the cylinder, is a piston. The piston separates the internal rod side from the internal cap side of the cylinder

3. Who Uses Hydraulic Cylinders?

Hydraulic cylinders are used in countless applications. They are often seen at work in both industrial applications (including hydraulic presses, cranes, forges, and packing machines), and mobile applications (such as agricultural machines, construction vehicles, and marine equipment)

Conclusion:

After reading this article, we can say that hydraulic cylinders offer versatility and higher power density as compared to other systems. They consist of fewer components than other cylinder systems.

Hope this article helps!