Multiple industries use hydraulic cylinders, including manufacturing, agriculture, mining, aerospace and constriction. These devices use pressurised fluid to exert force in a linear motion to perform various types of work, such as raising a crane on a building site or pushing a press into materials.
Hydraulic cylinders are popular because of their ability to exert extreme force on a target area. They offer remarkable power, control, and stability.
However, they can also be confusing, even for companies involved in hydraulic cylinder manufacturing. That’s where this article can help. We describe various hydraulic cylinder types and their applications so you can decide which you require. Remember, you can also discuss your options with a hydraulic fabrication brand.
Single-Acting Cylinders
Single-acting cylinders are the most basic hydraulic cylinder variant, having only one port for fluid to enter and exit. The high-pressure fluid pushes the piston in one direction, while a spring or an external load returns the piston to its original position.
Industries typically use single-acting cylinders for applications requiring a short stroke and relatively low force. They are also suitable for jobs where operators do not require a controlled or fast retraction, such as clamping.
Single-acting cylinders have the advantage of being affordable to produce and easy to install. With these, you get substantially lower valve and piping costs compared to double-acting cylinders (which we discuss in the next section).
However, most designs reduce thrust because of the opposing spring force. Moreover, pistons’ strokes can become inconsistent as units age because of the mechanical decay of the spring.
Double-Acting Cylinders
Double-acting cylinders are more common than single-acting and, as the name suggests, have two ports for the fluid to enter and exit. The fluid pressure pushes the piston in both directions, allowing for a longer stroke and a higher force than single-acting cylinders.
You typically find double-acting cylinders in applications requiring continuous reciprocating motions. These devices can extend and contract in machines without the help of a spring. Applications include:
- Moving items on and off conveyor belts
- Steering, lifting and braking
- Opening and closing valves (especially in high-pressure industrial systems)
- Opening or closing gates and loading dock doors
- Pressing and punching on production lines
- Powder coat spraying (if using robotics)
- Raising and lowering elements of heavy mobile machinery, such as work platforms
Telescopic Cylinders
Telescopic cylinders are a hydraulic cylinder type consisting of multiple stages of pistons nested inside each other. Pistons extend and contract sequentially, giving the cylinder a longer stroke than a single-stage cylinder of the same length.
Usually, you find telescopic cylinders in applications requiring a high extension-to-retraction ratio, such as aerial platforms, cranes, and rubbish trucks. However, you sometimes find them in agricultural equipment and transfer trailers.
The risk of hydraulic ram leak is higher on telescopic cylinders because they have more moving parts. Hydraulic ram repair usually requires removing old, damaged O-rings and replacing them with new ones.
Rodless Cylinders
Rodless cylinders are a slightly more exotic type of double-acting hydraulic cylinder. As the name suggests, these do not have piston rods. Instead, they use a slot along the cylinder barrel that allows a carriage to move along with the piston.
The carriage moves because of its connection to an external load by a belt, chain, cable, or magnet. The hydraulic power unit supply provides pressurised oil to the actuation system, which stores energy when combined with actuators.
Rodless cylinders are found in applications requiring long strokes and compact design. Use cases include:
- Packaging machines
- Linear actuators
- Conveyor systems
- Electronics manufacturing and assembly
- Material transfer
- Web cutting
- Loading and lifting
Tie-Rod Cylinders
Tie-rod cylinders are a special type of double-acting cylinder that incorporate four or more threaded rods (tie-rods) that hold the cylinder head and cap together. These additions provide extra strength and stability to the cylinder, making it more durable.
Most tie-rod cylinder applications are in the standard size and moderate pressure range. Common applications include:
- Industrial machinery
- Automotive equipment
- Hydraulic presses for folding, punching, clinching and forging various materials
Welded Cylinders
Welded cylinders are another type of double-acting cylinder with the cylinder head and cap welded to the barrel. This innovation eliminates the need for tie-rods, making the cylinder more compact and robust.
Usually, engineers use welded cylinders for applications requiring custom sizing and high pressures, such as:
- Construction machinery
- Marine applications
- Heavy-duty mobile equipment
Given this range of hydraulic cylinder options, you should choose one based on your specific needs and preference. If you need assistance selecting or installing hydraulic cylinders, always speak to professionals.