Category Archives: Hydraulic Cylinders

Hydraulic cylinders are devices that converts the energy stored in the hydraulic fluid into a force used to move the cylinder in a linear direction.

What are Hydraulic Cylinders?

Hydraulic cylinders are devices that converts the energy stored in the hydraulic fluid into a force used to move the cylinder in a linear direction.

Hydraulic cylinders

An example of a hydraulic cylinder

The device consists of a cylindrical barrel, piston, and a piston rod.
The piston within the barrel is connected to the piston rod, and the cylindrical bottom and head closes the bottom and the head of barrel respectively.
The cylinder head is situated where the piston rod exits the cylinder.


Hydraulic cylinders are classified according function.

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How do hydraulic cylinders work?

How exactly do hydraulic cylinders work?

hydraulic cylindersHydraulic cylinders are a complicated technology; they work from a mixture of pressure and movement in the cylinders themselves, which gives the energy of motion. Pressure is formed in the cylinders through hydraulic fuel, which stores the pressure under the cylinders. The energy in the oils are converted to motion through this process. In a hydraulic system, a motor consists of at least one hydraulic cylinder, but there are usually more. A pump is used to control the oil-flow in the system, which is part of the generator in the hydraulic system.

A hydraulic cylinder is built from a barrel, piston and piston rod. The piston itself is put into position inside the barrel, being connected to the piston rod. The base of the cylinder, and the head, are responsible for the closure of the head and base of the barrel. The bottom of the cylinder and the piston rod are then mounted through brackets. The piston in the cylinder consists of a number of seals and rings.

The process begins with the piston rod moving outwards, which builds in motion as the hydraulic fluid enters the base of the cylinder. A reversal of this is possible, where hydraulic fluid goes back into the reservoir from being pushed by the piston.

Varying classifications of hydraulic cylinders:

Single Acting Cylinders:

In single cylinders, the process is rather simple: the fluid is pressurised from one side in both the expansion and retraction process. A spring is used to return the cylinder to its original position.

Double Acting Cylinders

In double acting cylinders, any pressure generated from the fluid can be applied in both directions, which gives more power compared to single cylinders. The springs used in single cylinders aren’t used in stroke applications that require a large process, as there are problems associated with the spring.

hydraulic cylinder

An example of a hydraulic cylinder

What should you consider when buying a hydraulic cylinder?

These specs will need to be classified, yet here’s what you should be looking at:

  • Stroke
  • Bore Diameter
  • Cylinder Type
  • Rod Diameter
  • Operating Pressure Levels

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4 ways to reduce failures in hydraulic cylinders

hydraulic cylinder

An example of a hydraulic cylinder

As a product that’s used in a number of vehicles, hydraulic cylinders are as common as pumps and motors combined. If you use a lot of hydraulic equipment on a regular basis, then it’s more than likely going to be an expensive bill when the cylinder requires a repair. This can make up a considerable number of your overall operating costs, so taking these precautions should help the lower your bill and the damage dealt to the hydraulic cylinders.

According to various studies, a whopping 25% of mechanical equipment failures are down to a design flaw. If we apply this research to hydraulic cylinders, as many as one in four hydraulic cylinders are not designed for the application they’re currently operating in. This will just cause eventual breakdown of the machine or the hydraulic cylinder itself.

If you have any cylinders that don’t seem to last as long as they should, you may need to address one or more of the following issues:

Tube Ballooning

The cylinder tube can go through a process of ‘ballooning’, something which is usually caused by insufficient thickness of the wall and/or material strength in the cylinder’s operating pressure. Once the tube has ballooned, the tolerance between the piston seal and the tube wall is lost, which allows high-pressure fluid to bypass the seal. This fluid can actually erode the seal, with heating caused by the pressure drop across reduces the life of the seal. The end result is premature failure of the piston seal.

Bearing Area Is Insufficient

Given the surface of the bearing bands in the gland is insufficiently supporting the side thrust which is transferred to the cylinder, then an excessive load is placed on the rod and piston seals. This will result in the deformation of the seals, and ultimately, their failure.

The Finish of the Rod

The surface finish on the cylinder does have a significant effect on the life of the seal. Given the level of roughness on the surface is too low, the life can be reduced as a result. If the surface roughness is way too high, an unacceptable level of leakage is passes the road seal, which can result in poor performance.

In the sense of extending cylinder service life, you must think of the cylinder rod’s surface as a well lubricated, wear-surface, which you should treat accordingly.

In various applications, using an alternative rod surface treatment that has superior mechanical properties, which has conventional hard-chrome plating, such as nickel-chrome plating. These also have High Velocity Oxygen Fuel (HVOF) metal spraying, these can increase the service life of the rod and the seal.

Bent Rods

Bending cylinder rods can be caused by numerous insufficient rod diameter, even material strength. The improper cylinder mounting arrangement can cause damage to the rod. Once the rod bends, there are levels of deforming loads placed on the rod-seal. This increases the possibility of leakage and will ultimately result in the premature failure of the seal.

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How Hydraulic Cylinders work

Hydraulic Cylinder

An example of a hydraulic cylinder

Hydraulic Cylinders, used to help with the lifting, pushing, dumping, hauling, crushing, drilling and digging they’re maybe one of the most important mechanical inventions which has fitted around us.

When manufacturing a hydraulic cylinder the process is now a lot more streamline with much tighter tolerances, the sheer amazing amount of force a hydraulic cylinder can produce is based upon a mechanical principle of pressure. The way the pressure is worked out is by this formula – Area X Psi = Force.

Hydraulic Cylinder – More Explanation

The hydraulic cylinder has main parts which make up the mechanism which includes the Piston, a piston seals, rod and the gland and butt.

The Rod which the piston is attached to is attached to a large nut at one end, as one of the hardest working component it’s extremely strong to resist bending and is also made out of steel. The piston inside the hydraulic cylinder is used to help build pressure and is done by using a piston seals to keep pressure from bypassing each other.

The Gland is also known as the head of the cylinder and helpes the rod retract and extend, this part contains wiper and rod seals to help keep contamination out of the hydraulic cylinder.


So there you have it, this simple but yet extremely useful mechanism is built using simple parts with very good accuracy in determining the amount of pressure each hydraulic cylinder can produce.

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