Hydraulic Cylinder Suppliers

How Does a Hydraulic Actuator Work?

Hydraulic cylinder suppliers provide multiple sizes and configurations of actuators to perform different tasks, but each actuator follows Pascal’s Law of fluid mechanics. Pascal proved that when the pressure is altered in a fluid chamber, the resulting energy is evenly distributed throughout the chamber.

So, if there are two pistons in a fluid chamber and pressure is applied to one, an equal force acts on the second piston. Pressure is evenly distributed in the chamber because hydraulic fluid is an incompressible fluid.

When cylinder manufacturers develop a new cylinder for a specific application, they can calculate how much pressure the cylinder produces in a fluid chamber using Pascal’s P=F/A. This means that force (F) applied to a piston divided by the chamber’s area (A) equals the pressure (P). Some hydraulic systems are more complicated than others, but the basic hydraulic cylinder parts consist of:

• Cylinder barrel: The barrel is the cylinder’s housing. It has a smooth, honed surface, and its durable construction allows it to withstand high pressure while preventing leakage. Cylinder barrels are manufactured from drawn over mandrel (DOM) tubes or cold drawn Seamless (CDS) tubes. The barrel’s size depends on the application; larger barrels produce more force than smaller barrels.
• Cylinder base: The base seals the barrel at one end. Also called the rod end, the base is attached to the barrel with threading, welding or bolts. The equipment utilizing the hydraulic pump is mounted at the cylinder base.
• Cylinder head: The head seals the barrel at the other end and uses seals and bearings to guide the piston when it extends or retracts.
• Piston: The piston houses the piston rod and divides the barrel into two separate chambers.
• Piston rod: The piston rod is the workhorse of the cylinder that responds to the changes in hydraulic pressure by extending or retracting. The machine that operates the pump is attached to the piston rod.
• Seal gland: The gland contains a series of seals that prevent fluid leakage between the piston rod and cylinder head. The gland typically includes a primary seal, secondary seal, wiper, static seal, scraper and wiper bands. The wiper and scraper seals prevent dirt and water from contaminating the cylinder.

The seal’s composition depends on the hydraulic actuator’s application. Seals are manufactured from several materials, including rubber, Teflon, metal, polyurethane and fluorocarbon. For lower temperature operating conditions, elastomer (constructed of nitrile rubber) seals are used. Fluorocarbon seals are used in actuators in high-temperature environments.

Choosing a Hydraulic Actuator

Selecting an inadequate actuator for an application can cause equipment damage and injuries. At Yates Cylinders, we can work with you to develop a customized cylinder for your operation. Some of the factors involved in the design process include:

• Mass: Heavier objects require larger cylinders.
• Movement: The movement involved in the application helps determine the type of actuator.
• Bore Size: Larger bore sizes can handle more mechanical force.
• Rod Size: The rod buckling strength, bearing load and the length of the cylinder’s stroke are factors that determine the rod size.
• Cushioning: High-torque applications often require cushioning to protect the cylinder.

Hydraulic vs Pneumatic Cylinders

Hydraulic actuators utilize incompressible fluid to produce linear motion, while pneumatic cylinders operate with compressed air generated by a hand pump or compressor. Determining whether a machine requires a pneumatic or hydraulic cylinder depends on the operating conditions, the force required, and the application type. Both actuator types are used extensively in various industries, and both of them have strengths and weaknesses.

Pneumatic Cylinders

If you’ve used a hand pump to inflate a tire, you’re familiar with a pneumatic cylinder in its most basic form. Industries that commonly use pneumatic actuators include manufacturing, medical, automotive, mining and water treatment.

Advantages

Compared to a hydraulic actuator, a pneumatic cylinder has a simpler design that requires fewer internal components. That means it’s easier to maintain and repair than a hydraulic model. The most significant advantage of a pneumatic cylinder is its accuracy. It’s accurate to 0.1 inches and repeatable by 0.001 inches. The accuracy of pneumatics is on full display in manufacturing plants where actuators open and close tiny valves at an astonishing rate.

Pneumatic pumps are invaluable in industries such as food processing and pharmaceutical production. If the pump fails, the leaking compressed air cannot contaminate the product. Unlike hydraulic pumps, pneumatics can be used for applications that require miniature pumps and lighter materials.

Disadvantages

Although it’s accurate, the pneumatic pump is less efficient than a hydraulic model. The air compressor has to run constantly to provide air and requires regular maintenance to keep the actuator functioning. Unlike hydraulic cylinders, pneumatic units are application-specific. If you need a pneumatic pump for another job, you have to purchase a separate cylinder.

Hydraulic Cylinders

Used in anything from a standard forklift to a massive excavator tool, hydraulic cylinders are efficient devices with distinct advantages over pneumatic actuators.

Advantages

While pneumatic actuators require a constant supply of compressed air, hydraulic actuators rely on a set amount of hydraulic fluid that does not need replenishing. Pneumatic pumps must be located close to the compressor to function efficiently, but hydraulic pumps can be positioned away from the motor without changing the pressure level.

The greatest advantage of the hydraulic cylinder is its power. It can produce up to 4000 psi and create mechanical force 25 times as powerful as a pneumatic actuator.

Disadvantages

Maintenance is a greater concern with hydraulic units because they have more internal parts. If the cylinder ruptures, the fluid can contaminate the area and lead to a messy cleanup process.

Common Types of Hydraulic Cylinders

Hydraulic cylinder manufacturers can produce multiple types of hydraulic actuators for numerous applications. Here are the four most common types used today.

• Single-Acting: The piston in a single-acting cylinder moves in one direction, and it returns to its original position with help from a spring or motor.
• Double-Acting: The hydraulic fluid travels through one port when it extends and exits through another port when it retracts.
• Tandem: Tandem cylinders use two barrels connected by one piston. They’re often grouped together in a series to produce more mechanical force.
• Telescopic: Telescopic units are arranged with multiple single-acting cylinders.

Typical Applications of Hydraulic Linear Actuators

Hydraulic cylinders play a crucial role in the construction, aviation and manufacturing industries. They’re used in backhoes, dump trucks, excavators, aircraft, loaders, presses and injection molding equipment.

Single-Acting Hydraulic Cylinder vs Double-Acting

Single-acting and double-acting cylinders are two the most common cylinder types used in equipment and production lines. Since single-acting cylinders are less complex, they’re easier to maintain than double-acting cylinders. However, double-acting cylinders give the operator more control because of the larger volume of fluid in the chamber.

Hydraulic Cylinder Repair Services

At Yates Cylinders, we have the largest, most extensive repair facility in the Midwest. We’re available 24 hours a day, and we offer delivery and pickup. We have a massive inventory of repair parts, and we can fix any make or model of cylinder.

We have locations in Ohio, Michigan, Alabama and Georgia and offer a wide selection of hydraulic actuators for multiple applications.