Single And Double Acting Hydraulic Cylinder

Double-acting hydraulic cylinder
The most common hydraulic cylinder structure is a double-acting hydraulic cylinder, which sends pressurized fluid into the connecting rod end of the double-acting cylinder, causing the piston rod to retract. Conversely, injecting pressurized fluid into the bonnet end will cause the valve stem to extend. At the same time, the fluid on the other side of the piston returns to the hydraulic reservoir. (If the fluid medium is air, it is usually discharged into the atmosphere.)
Because the end face area of the rod end piston is smaller than the end face area of the bonnet, the extension force is greater than the contraction force (assuming that the fluid pressure is equal). Because when the cylinder is fully retracted (due to the volume of the rod), the total volume of the cylinder is smaller than when the cylinder is fully extended, so the cylinder retracts faster than it extends (assuming equal flow)
Single-acting hydraulic cylinder
Single-acting cylinder, which only accepts pressurized fluid on one side of the piston; The volume on the other side of the piston is discharged into the atmosphere or returned to the tank. Depending on whether it is directed to the head end or rod end, the pressurized fluid can stretch or shrink the cylinder respectively. In both cases, the force generated by gravity or spring restores the piston rod to its original state. The hydraulic jack for vehicles represents the common application of single-acting and gravity return cylinder.