How To Use Different Types of Hydraulic Cylinders

Your semi-truck is a collection of many parts that all work together to keep it on the road. If just one of these parts stops working, it can lead to major issues that put the whole operation at a standstill. One part that's especially critical is the hydraulic system, which controls functions like braking, steering, and lifting.

The hydraulic system itself is made of many components, but the hydraulic cylinder is one you should know about. It’s the muscle behind the system. If your hydraulic cylinder fails, you may need to replace it with a new one. With so many options out there, it can be tough to figure out which one is right for your rig. Let's look at the different types of hydraulic cylinders and how to use them to help you choose the correct one for a repair.

How Hydraulic Cylinders Work

So, what is a hydraulic cylinder, and what does it do? A hydraulic cylinder is a mechanical actuator that uses pressurized hydraulic fluid to create linear force and motion. In simpler terms, it converts the fluid pressure into a powerful push or pull action.

The basic setup includes a cylinder barrel, a piston, and a piston rod. Pressurized fluid enters one side of the cylinder, pushes the piston, and extends the rod. To retract the rod, fluid is sent to the other side. This simple back-and-forth movement is what powers many of your truck's most demanding functions. Without a functioning cylinder, systems like your dump bed or liftgate are just dead weight.

Different Types of Hydraulic Cylinders and How to Use Them

Not all cylinders are built the same. They come in various designs, each suited for specific tasks. Let's break down the main types you'll encounter.

Single-Acting Cylinders

Single-acting cylinders are the straight shooters of the hydraulic world. They use hydraulic pressure to push the piston in only one direction. To return to its original position, the cylinder relies on an external force, like a spring or gravity.

You'll find these cylinders in applications where force is needed in just one direction. A common example on a semi-truck is a dump hoist. Hydraulic pressure raises the bed to dump the load, and then gravity brings it back down once the pressure is released. They’re simple, reliable, and get the job done without extra complexity.

Double-Acting Cylinders

Double-acting cylinders are a bit more advanced. Unlike their single-acting cousins, they use hydraulic pressure for both extending and retracting the piston rod. They have ports at both ends of the cylinder barrel, which allows fluid to push the piston in either direction.

This design gives you precise control over movement in two directions. Think about the hydraulic systems on a loader or an excavator arm—they need to push and pull with equal force. On a semi-truck, you might see them in steering systems or specific types of liftgates that require powered movement both up and down. These cylinders are versatile and provide powerful, controlled motion.

Telescopic Cylinders

Ever seen a dump truck with a bed that seems to extend to the sky? That's a telescopic cylinder at work. These are also known as multi-stage cylinders. They consist of a series of nested steel tubes, called stages, that extend and retract like an old-school telescope.

Telescopic cylinders are perfect for jobs that require a very long stroke from a compact, retracted length. They can be either single-acting or double-acting. On a semi, their most common use is for dump trailers, where a long reach is needed to lift the bed to a high angle.

Tie-Rod Cylinders

Tie-rod cylinders are a common sight in industrial and mobile applications. Their name comes from the threaded steel rods that hold the two end caps to the cylinder barrel. These tie-rods provide strength and stability, which makes the cylinder easy to assemble and service.

You can find these cylinders in a variety of light- to medium-duty applications on trucks, like certain types of liftgates or clamping mechanisms. Their main advantage is that they are easy to repair. If a part fails, you can often disassemble the cylinder and replace the damaged component without needing to replace the entire unit.

Welded Body Cylinders

Welded body cylinders are the tough guys. Instead of tie-rods, the end caps are welded directly to the cylinder barrel. This construction creates a very strong, rigid, and compact unit that can handle high pressures and harsh conditions.

Heavy-duty applications that require high durability, such as construction equipment, agricultural machinery, and rugged systems on semi-trucks, use welded cylinders. The downside is that they’re more difficult to repair. A failure often means you’ll need to replace the whole cylinder.

How To Determine Which Hydraulic Cylinder To Use

Choosing the right cylinder is about matching the tool to the job. First, identify the application. Do you need force in one direction or two? A single-acting cylinder is fine for lifting, but you'll need a double-acting one for tasks that require both push and pull force.

Next, consider the stroke length and available space. If you need a long extension from a compact space, a telescopic cylinder is your best bet. For standard applications, the choice between a tie-rod and a welded body cylinder often comes down to serviceability versus durability. If you prioritize easy maintenance, go with a tie-rod. If you need maximum strength for a tough job, a welded cylinder is the way to go.

Finally, always check the pressure ratings and mounting style to match your truck's existing system. Making sure these details are correct will help you avoid leaks or connection problems and guarantee the safe operation of your equipment.

Your Next Repair, Made Easy

Now that you know more about the different types of hydraulic cylinders and how to use them, you should be able to select the one you need and fix any issues with your semi's hydraulic system.

At Higgs Parts, we sell hydraulic cylinders from trustworthy brands like Hyga. Our hydraulic parts are built to help optimize the flow of pressure, power, and air within your vehicle's systems. These components keep heavy-duty trucks operating at peak potential. If you need parts for a repair, come see us.