What is a Single Acting Hydraulic Cylinder?

For some people, hydraulics is a strange mystery and they don’t even know the difference between a double and single acting hydraulic cylinder. However, all that is about to change, once you digest this information. It’s time to enter the world of hydraulics and check out both single and double acting cylinders.

One Action Only

Single action means there is only one-way hydraulic force can be applied. In this process, you have a cylinder with a piston inside. A rod is attached to the piston and in some cases, a spring is attached to the piston rod. There are two sides of a cylinder (with a piston). They are as follows:

Rod end – this is the end where the piston rod is located.

Blind end – there is no piston rod, just the head of the piston and hydraulic fluid.

A single acting hydraulic cylinder only has one fluid port and it is in the blind end of the cylinder. Fluid is pumped into the blind end and as pressure builds, it moves the piston in the opposite direction. Once the piston bottoms out, fluid pressure is released and a spring or other mechanism returns the piston to its previous position. It doesn’t always have to be a spring mechanism, as another cylinder or even a rotating flywheel can serve the same purpose.

The rod end of the cylinder never receives fluid so it does not get any lubrication from the process. Single action cylinders are commonly used in automotive jacks. They are also used in auto brake master cylinders and automated factory applications.

Double Action

To better understand single action, let’s talk about double action cylinders. Dual action cylinders have a fluid port on both the blind and piston rod ends. Fluid enters the blind side and pushes the piston back. As this occurs, it displaces the fluid in the rod side. Next, the same thing happens in reverse. As fluid enters the rod side, it pushes out fluid in the blind side. Because both ends of the cylinder have fluid at all times, there is better lubrication and less chance for corrosion. This system requires a smaller reservoir for hydraulic fluid. Double action cylinders are the most common types and are used anywhere a back and forth motion is required. For example, a lift truck extends when lifting and retracts when lowering.

Benefits of the Single Acting Hydraulic Cylinder

Because these cylinders are simple in design, they are cost effective. They also require less energy to operate. No matter which design you choose, make sure to select a trusted and experienced manufacturer for all your hydraulic components.

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