For any industry that relies on fluid power systems, and particularly on hydraulic machinery, it’s necessary for operators to understand how cylinder force is generated and calculated. Ensuring that the appropriate amount of force is applied for each situation is a critical step in maximizing the productivity of the machinery and maintaining its functionality. However, because there are so many variables in play that affect the final output, this can be a complex topic.
In the following blog post, we’ll review the essential steps needed to determine the force produced by a hydraulic cylinder. Then we’ll discuss how to find the correct inputs to enter into a cylinder force calculator so that you can ensure an accurate reading and an effective operation.
Why Calculate Hydraulic Cylinder Force
Cylinder force—the amount of push or pull a hydraulic cylinder can generate—directly translates to the lifting, pushing, or pulling capacity of hydraulic machinery. The greater the force, the higher the system’s capacity to move objects, and accuracy is key.
For a hydraulic system to work safely and effectively, it must be able to generate the proper amount of cylinder force for a given job. Calculating the cylinder force before you begin a project will help you determine if your specific equipment can perform a specific job.
Knowing the cylinder force of your system is equally crucial when you’re installing the machinery, replacing parts, or making repairs. Each element of the system must be able to withstand the amount of force that will be generated, or you’ll risk lower efficiency and serious damage to the system.
Keep in mind that scaling any parts up will most likely necessitate scaling up the entire machine, which will require larger and more heavy-duty parts to ensure effective operation. For example, a larger piston will require a larger cylinder, resulting in needing a greater fluid volume. Consequently, a larger and more powerful pump will be necessary to provide the appropriate psi to generate movement in the system. Accurate calculations will help you ensure your equipment can carry out the work you need it to do.
Although it’s possible to crunch the numbers by hand, to accurately determine the cylinder force of your hydraulic system, we recommend using a cylinder force calculator such as the one on the Aberdeen Dynamics website. To do so, you’ll need three measurements: the pressure (psi), the cylinder blind end area (in square inches), and the diameter of the rod. Here’s how to find those numbers:
Calculating Pressure
The first piece of information you need to determine the cylinder force in your hydraulic system is the psi (pounds per square inch) of your pump. This is the measurement of the pressure that the system can create, and it is likely printed on a label on your pump. If not, check the manual or contact the manufacturer to help you determine output pressure. Most hydraulic pumps have adjustable psi, so it may be listed as a range or just a maximum psi. You’ll need the maximum number for your calculations.
It’s important to note that there are several factors that can impact the psi in the hydraulic cylinder. For example, anytime there is a twist or turn in the tubing connecting the pump to the hydraulic cylinder, it will slow down the flow rate and cause the pressure to drop somewhat. Denser hydraulic fluid will also flow more slowly, reducing the ultimate psi. While these factors have a negligible impact on most systems, they are still useful to know before entering any inputs in your cylinder force calculator.
Determining the Area of the Cylinder Blind End: The Affected Piston Area
Pascal’s Law states that the force applied to the fluid in a container is equally applied to every other point in the container. A larger container, assuming the pressure is equal, can therefore accommodate a larger piston, allowing for greater levels of force to be generated. For this calculation, you need to determine the affected area of the piston.
This can be determined by measuring the area of the blind end of the cylinder (the end that is opposite the piston rod). To do so, measure the diameter of the cylinder, divide it in half to find the radius, square the radius, and multiply the radius-squared by pi (3.14).
Aberdeen Dynamics also has a calculator to save you the work. Find the calculator symbol at the top of the page, select the “Cylinder blind end area (sq in),” enter the diameter of the cylinder in inches, and hit Enter.
Putting It All Together
Note that we haven’t included a separate section explaining how to measure the diameter of the rod because it’s exactly what it sounds like: the diameter of the piston rod in inches.
Once you have determined the psi, blind end area of your hydraulic cylinder, and rod diameter, you can enter this information in the hydraulic force calculator on our website to determine the cylinder force. Simply click on the calculator symbol at the top of this page. Then:
- Select the “Cylinder output force (lbs)” calculator in the drop-down menu
- Input the psi, blind end area, and rod diameter numbers from your earlier calculations
- Hit Enter on your keyboard
The calculator will immediately calculate the exact push force output in pounds. For push force, the calculation uses the full piston area. For pull force, subtract the rod area from the piston area to account for the space taken up by the rod.
Of course, this calculation can be made by hand using a regular calculator, but it involves several more steps and more chances for error. Using the cylinder force calculator saves time and ensures accuracy. When it comes to equipment that is vital to your company, it’s best not to take any chances. If you have further questions or if you are in need of customized machinery parts to meet a specific force output requirement, contact Aberdeen Dynamics and let our experts advise you on the best course of action.