There are two options to consider in hydraulic cylinders, aside from the specific style and design of the cylinder. In both welded and tie rod styles of cylinders, there is also the single and double acting option.
The Action
The single acting cylinder has one port for the hydraulic fluid, which is at the base of the cylinder. When the cylinder is extended, the hydraulic pump pushes fluid, under pressure, into the base of the cylinder which causes the rod to rise up and push or lift the load. As long as the operator continues to apply the pressure, the load lifts to the maximum height.
Then, to cause the rod to retract, the pressure from the pump is removed. This allows the fluid to flow out of the port and out of the cylinder, allowing the retraction to the fully retracted position. The weight of the equipment or the load, as well as the action of gravity, results in the downward or backward movement of the rod.
Unlike the single acting cylinder, the double acting cylinder has two ports and two corresponding hoses to the hydraulic system. This allows the fluid to be pushed into the cylinder from both directions, controlling both the extension and retraction of the rod.
Compact Spaces
The use of a single acting cylinder, particularly those with the welded cylinder body, allows for a more compact system for use in confined spaces. In most equipment and systems this is a primary consideration in both the design stage as well as in finding replacement cylinders.
Low Maintenance Requirements Applications
When the correct size and load capacity cylinder is selected, the single acting option provides a lower maintenance type of system based on their streamlined design. When cylinders are located in difficult to access areas, this is an important consideration.
