A simple device, hydraulic cylinders are usually made up of two main parts: an outer cylinder barrel containing hydraulic fluid, and a hydraulic piston which is connected to a rod which moves it up and down inside the barrel.
The distance that a piston travels with the cylinder until it is fully extended is known as its stroke. The length of a stroke is often used to classify the cylinder and this length can range widely from less than an inch to several feet in length in relation to the power required.
Hydraulic cylinders are used commonly in automobiles in the transmission, brakes, steering, in aviation, industrial and construction machinery for example as excavators. Hydraulic cylinders are typically one of two types: tie-rod cylinders or welded cylinders. Both systems are similar in that the outer cylinder barrel is typically made of steel or aluminum, and the maximum pressure that the cylinder can sustain is directly related to the maximum output of the hydraulic cylinder.
They can be single-action or double-acting designs depending on whether a cylinder’s piston produces pressurized motion in one direction or in both directions. The piston is located inside the barrel housing and is commonly chrome-plated to prevent any deterioration due to wear and tear or corrosion.
Most often, the hydraulic fluid used in a cylinder is an oil. This will need to be periodically replaced or refilled as it is affected slowly by the process of pumping the piston. Other hydraulic systems use water as the motion fluid which is less expensive than hydraulic oil, and does not result in pollution, making water hydraulic cylinders an environmentally friendlier solution. There are a number of factors to consider regarding hydrolic cylinders such as the maximum power, the mounting and configuration setup of the machine itself in relation to elements to be worked on, the materials used in the cylinders and the stroke itself.
As the motion produced by the pressure inside hydraulic cylinders is linear, the machine components should not be placed under any indirect tension or strength as it may cause damage to the parts which would result in loss of pressure, and therefore loss of power. To ensure the best results from the machine, the cylinders should only be used for pushing and pulling. Hydraulic cylinders range in price according to their capabilities but are an investment at any size. However, due to the potential power output of even a small hydraulic system, the paybacks are often satisfactory.