How to Select a Hydraulic Cylinder & Power Unit
Selection of the proper components for a hydraulic system is quite simple when you use the accompanying table and chart. Here is an example to illustrate their use. Assume your requirements are: 20,000 lbs. of force, 28” stroke, and 7.5 seconds for full cylinder extension.
The table below shows a 3” diameter cylinder will develop 21,204 lbs. of force with 3000 psi pressure.
A line has been drawn on the chart from 3” diameter through 28” stroke.
By continuing this line, it intersects 200 cubic inch displacement.
Another line drawn from 200 cubic inches through 7.5 seconds intersects 7 GPM.
Using this example, the chart and table show that your components should be a 3” diameter 3000 psi cylinder and a hydraulic power unit with approximately 7 GPM and 3000 psi rating.
Theoretical horsepower for these values would be 12.25 hp. However, since most applications usually require maximum GPM and pressure for only a very short portion of each cycle, the electric motor of the hydraulic power unit will usually be considerably smaller (one half or less.)