How to choose a hydraulic cylinder?

In our hydraulic selection guide, we will go through the many aspects to consider when choosing a hydraulic cylinder for a given application.

A hydraulic cylinder can push or pull in a straight line. It comprises a hydraulic push/pull cylinder, piston, and rod assembly enclosed within a cylindrical bore that hydraulic fluid pressure and flows to create mechanical force and linear motion.

The appropriate selection of a hydraulic cylinder necessitates considering a variety of parameters impacted by the intended use. The amount of force required, force direction, and ways of halting the workload are all considered. These elements must be taken into account to estimate the needed cylinder parameters for any given application accurately.

Tips for Selecting the Right Hydraulic Cylinder

Hydraulic push/pull cylinders use fluid pressure and flow to create linear motion and force in industrial and mobile devices, such as presses and plastic molding machines. Hydraulic linear-motion systems are also more straightforward, durable, and have a higher power density than pneumatic, mechanical, or electric linear-motion systems.

Hydraulic cylinders come in a wide range of kinds and sizes to accommodate a variety of applications. For optimal performance and dependability, choosing the correct cylinder is crucial. Here are some helpful hints for choosing, sizing, and using the right one for the job.

Selection factors to consider

1. Select the appropriate cylinder type.

Tie-rod and welded cylinders are the two most used hydraulic cylinder types for industrial purposes.

For added strength and stability, tie-rod cylinders employ high-strength threaded steel tie rods on the exterior of the cylinder housing. 

They are utilized in most typical industrial applications, such as plastics machines and machine tools. However, their maximum working pressure is usually limited to 3,000 psi. Because the cylinders are designed to specific standards, their dimensions and pressure ratings are interchangeable with any other compliant cylinder.

Welded or mill-type cylinders have a heavy-duty housing and a barrel that is welded or bolted directly to the end caps, so no tie rods are needed. 

They are commonly used in demanding applications like presses, steel mills, and offshore locations with harsh conditions and extensive temperature fluctuations. They are designed for higher pressures, up to 5,000 psi or more significant.

2. Choose the appropriate pivot mountings.

Pivot mounts allow a cylinder to shift alignment in one plane while absorbing stress on the cylinder centerline. Clevis, trunnion and spherical-bearing mounts are all familiar.

Clevis mounts are suitable for short strokes and small to medium-bore cylinders and can be utilized in any direction. Cylinder engineers favor spherical bearing clevis mounts over plain bearing clevis mounts because they allow for more misalignment and are thus more forgiving. 

They propose a pivoting rod-end connection, such as a spherical rod eye, if utilizing a spherical bearing on a rear clevis.

The combination helps to adjust for any potential misalignment or side loading. Head, mid, and rear-mount trunnion mounts are available. The mid-trunnion design is perhaps the most popular, as it gives designers a little more leeway. 

Depending on the application, they can be placed directly in the middle of the cylinder or almost anywhere toward the front or back. The mount, however, is not adjustable after it has been chosen.

3. Keep an eye out for impact loads.

The length of a stroke, or the distance it takes to push or draw weight, can range from less than an inch to several feet or more. However, ensure that the piston does not bottom out and create impact stresses after the stroke as the hydraulic push/pull cylinder extends or retracts. 

Engineers can choose from a variety of options: 

• Add internal cushions to reduce the load at the end of the stroke.
• Utilize proportional-valve technology to precisely meter flow and safely decrease the load.
• Alternatively, use an external mechanical stop to prevent the cylinder from bottoming out.

4. Add in a safety element.

While design calculations are essential, real-world operations are not the same as academic outcomes. Assume that peak loads will necessitate more force. 

The general rule is to select a cylinder with a tonnage rating of 20% higher than the load’s need. This compensates for losses such as load friction, hydraulic efficiency losses, real pressure below rated system pressure, cylinder seal and bearing slippage, and so on.

Essential Factors to consider hydraulic push/pull the cylinder

Consider the following factors when buying a hydraulic push/pull cylinder:

1. Mass

The first and most crucial step is to figure out how much mass you want to shift. After you have calculated your mass, you will need to examine how it will affect the force needed to move it. 

A 1-ton mass pushed straight up will require somewhat more than 1 ton of force, but a 1-ton load moved over the ground will require enough force to overcome friction and acceleration. Regardless, the hydraulic push/pull cylinder’s force should always be sufficient to provide room for mistakes.

2. Mechanics

After you have determined the type of the mass to be shifted, you will need to examine the geometry involved. The geometry of a machine like a hydraulic press, which generally goes up and down, is straightforward and requires no additional thought. 

The force needed by the hydraulic push/pull cylinder varies when the center of the load being moved is not centered on the point of lift force and is at perpendicular angles. For example, when using a crane, the hydraulic push/pull cylinder pulls the boom far away from the cargo.

3. Bore Size

After you have determined the force your hydraulic push/pull cylinder requires, the following step determines the cylinder’s bore size. The cylinder’s force is just the product of the system pressure multiplied by the area of the internal piston surface that the pressure acts onto. The hole size required to generate that force is calculated using a formula.

What is Next?

After understanding the deep analysis of the hydraulic cylinder, you can now get a hydraulic push/pull cylinder for yourself. Also, let us know if you have any confusions. We’ll make it more easier for you.