Single-Acting vs. Double-Acting Hydraulic Cylinders

Hydraulic cylinders convert fluid pressure and flow into powerful force and velocity. This converted pressure is then used to help create most of the heavy-lifting equipment around us- from dump trucks and bulldozers that we see on construction sites to gigantic cranes and stadium lights. For all these and everything in between, hydraulic cylinders ensure that the job is done in a smoother, more reliable, and more efficient process, making it an imperative in different industrial fields.

You can find hydraulic cylinders in nearly every mechanical utility and contraption involving heavy-duty push and pull. They come in a variety of sizes, customized designs, and configurations, making them suitable for different forms of applications.

What Is the Difference between Single-Acting and Double-Acting Hydraulic Cylinders?

There are two primary ways hydraulic cylinders are manufactured: single-acting and double-acting models. Below, we discuss their main operational differences to help you decide which one best suit your needs and applications.

Single-Acting Hydraulic Cylinders

As their name denotes, single-acting cylinders act in a single direction, meaning that the cylinder can only move in one direction when applied oil flow. For this cylinder to return to its original position, an external force must be supplied to bring the oil back to the pump or system. Some cylinders rely on gravity to go lower; an example is a forklift. While other cylinders, like standard jack cylinders, use an internal spring to return to the original position.

The fluid only applies pressure on the piston’s single side in a single-acting hydraulic cylinder. The cylinder rod will extend whenever a force is applied through a hand, gas, or electric pump. This force pumps the oil into the cylinder’s oilport, making jacking, pushing, and tensioning applications possible.

The most common for the action to be in the extended direction, however, there are many kinds of single-acting cylinders.

Double-Acting Hydraulic Cylinders

Double-acting hydraulic cylinders allows for the pressure of the hydraulic fluid to be applied on both sides of the piston. This produces direct extension and retraction control, without supporting a spring or external force to help it return to its original position.

This type of cylinder has two connection ports at both ends of the cylinder’s body. The cylinder can extend or retract depending on which port the oil flow is delivered..

In addition, there can be a variety of combinations of hydraulic pumps and valves connected to these cylinders that enables control of the specific motion or performance of the hydraulic system.

Advantages of Using Single-Acting Hydraulic Cylinders

The simplistic build and design of single-acting hydraulic cylinders provide fewer maintenance components. For a project or machine that requires an efficient and reliable hydraulic cylinder, single-acting may be your best option.

Here are some advantages of single-acting hydraulic cylinders:

• Easier to control. Single-acting cylinders have just one port for the hydraulic fluid to enter for a more calibrated and maintained pressure. This entails less complexity in the hydraulic system required to control it since oil flows only through one hose.

• Cheaper. Because of this style’s single-acting nature, the overall cylinder assembly is more straightforward, and this generally implies less material, seals, and complexity that can drive up costs. With only a single port to support instead of two, piping and valve purchases cost much less. Single-acting hydraulic cylinders have lower manufacturing, installation, and repair costs.

The process of using a single-acting hydraulic cylinder is highly effective when it comes to equipment and various devices. It is mainly used by those who want to simplify otherwise complex tasks.

Advantages Of Using Double-Acting Hydraulic Cylinders

Double-acting cylinders offer greater complexity. Unlike single-acting cylinders, they can transfer hydraulic fluids or output forces in extending and retracting directions. In addition, double-acting cylinders can cater to more unique industrial systems, thanks to their pressing and pulling power without the aid of external power sources. Because of this, they are the market’s most commonly used cylinder type.

Here are some advantages of double-acting hydraulic cylinders:

• Strong Versatility. Despite not being the best option for compact spaces, double-acting hydraulics are incredibly versatile. Ports on both ends make hydraulic power available in both directions resulting in an easily controlled push-and-pull motion.

• Longevity and Low Maintenance. Due to the nature of a double acting cylinder, most of the internal components are sealed off from the environment and immersed in oil. The seals prevent the ingress of contaminants that would degrade and wear down components in both the cylinder itself, and the hydraulics system that powers it. Immersing the components in oil keeps parts lubricated, keeps water out, and maintains operational temperatures. Depending on the system, the oil can also take away contaminants that work itself into the cylinder away, and work through filters.

Both of these major features result in double acting cylinders and their systems having a longer service life, which results in significantly lowered maintenance costs for the lifetime of the cylinder and system.

ISO Compliant Hydraulic Cylinders

ISO standards guarantee every industry’s safety and cohesive operations. Most cylinders use these standards for their ports, mounts, bores, strokes, seals, and other features. This facilitates compatibility of connecting cylinders into existing systems, generally lowers maintenance costs, and guarantees safety if operating pressures and conditions are not exceeded. This varies from each manufacturer, and here at Fluid Tech Hydraulics Inc., we can manage ISO standard cylinders, along with any custom or special application cylinders that have unique specifications.

Applications of Single and Double-Acting Hydraulic Cylinders

Double-acting cylinders work best for complex applications, including heavy lifting in one direction. In contrast, single-acting cylinders are more suitable for more straightforward applications.

Typical Single-Acting Hydraulic Cylinder Applications

• Hydraulic Rams
• Jacks
• Lift cylinders

Typical Double-Acting Hydraulic Cylinder Applications

• Steering mechanisms
• Balers
• Hydraulic Presses
• Construction Equipment

Quality Hydraulic Systems by Fluid Tech Hydraulics Inc.

When choosing the hydraulic cylinder that best suits your needs and application, it’s essential to know that you are working with specialized experts who know how to deal with all the components of the machine in the industry and various applications that relate to it.

If you’re looking for a partner for your next machining project, we at Fluid Tech Hydraulics Inc. have one of the most extensive and complete facilities for hydraulic cylinders on the West Coast. In addition, we provide a broad range of solutions, from resealing cylinders to designing and manufacturing custom cylinders based on your specifications.

Contact us today to learn more about our machining services or discuss your machining requirements with one of our experts.