Single Acting Cylinders
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| Illustration 1 | g01064842 |
Illustration 1 shows a single acting cylinder.
The tubular outer housing is the cylinder body. The following items are inside the cylinder body: piston, piston seal and the rod. The bore refers to the inside diameter of the cylinder body. The head end refers to the piston end of the cylinder. The rod end refers to the end from which the rod extends and the rod retracts.
Vertical Lift Gravity Return Operation
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| Illustration 2 | g01064844 |
Illustration 2 shows the single acting cylinder that is often used on vertical lift gravity return operations. The control valve directs oil to the head end of the cylinder. The oil pressure acts upon the piston to extend the rod and to lift the load. Gravity acting on the load is used to retract the rod and to lower the load.
Double Acting Cylinders
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| Illustration 3 | g01064934 |
Illustration 3 shows a double acting cylinder. The double acting cylinder is the most common hydraulic actuator that is used today. The double acting cylinder is used on the implement, the steering, and other systems where the cylinder is required to do work in both directions.
The National Fluid Power Association (NFPA) guidelines are used for the standards in bore size, mounting style, and overall dimensions of the cylinders. This allows cylinders from different manufacturers to be interchangeable when the cylinders have the same description. You must remember that cylinders may be equal in size without being equal in quality.