Hydraulic cylinder It is a widely used structural configuration in hydraulic systems. To design and operate such hydraulic cylinders correctly, it is essential to understand their characteristics, relevant applications, and key considerations.

　　1. Single-piston hydraulic cylinder.

　　This type of hydraulic cylinder has a piston rod only on one side, resulting in unequal effective areas on either side of the piston. The larger the diameter of the piston rod, the greater the difference between the effective areas on the two sides. Under identical supply pressures, the thrust generated on the rodless side is greater than that on the rod side. At equal flow rates, the piston‑rod extension speed driven by pressure oil on the rodless side is slower than the piston‑rod retraction speed driven by pressure oil on the rod side.

　　Note: This is particularly well suited for applications where the piston rod, when extended, generates substantial thrust and returns at high speed—making it ideal for scenarios in which the piston rod can withstand loads in one direction and perform rapid no‑load return strokes. The thicker the piston rod, the greater the difference between thrust and pull forces, resulting in slower speeds; conversely, thinner rods yield higher speeds. By employing a single‑rod hydraulic cylinder, the hydraulic gantry table achieves slow‑speed operation during work cycles and rapid return strokes.

　　2. Double-piston rod hydraulic cylinder.

　　This type of hydraulic cylinder has piston rods on both sides of the piston. When the diameters of the two piston rods are identical and the supply pressure and flow rate remain constant, the piston’s reciprocating speed and the force it generates are equal. Moreover, with two piston rods, this cylinder exhibits improved rigidity and stability.

　　Note: This type of cylinder occupies a large footprint during operation, with a working envelope approximately three times the length of its effective stroke. It is primarily used in grinding machines.

　　3. Single‑function hydraulic cylinder.

　　This hydraulic cylinder is a relatively simple type of hydraulic cylinder. It can supply pressurized oil only to one side of the piston, generating force in a single direction; the return motion is achieved by external load forces, spring forces, or the self-weight of the piston rod or piston, meaning there is no hydraulic force acting in the opposite direction. Its advantages include reduced hydraulic power consumption and a simplified hydraulic circuit.

　　Note: The speed and force in the reverse direction cannot be controlled. The self-weight, load force, and spring force that drive the piston rod or plunger back must exceed the sum of the back pressure and frictional resistance in all parts of the hydraulic cylinder. When using a spring‑return hydraulic cylinder, the spring should have sufficient clearance to allow for an increase in its volume.

　　4. Dual‑function hydraulic cylinder.

　　This type of hydraulic cylinder is more widely used than single‑acting hydraulic cylinders. Pressurized oil can be alternately supplied to both sides of the piston, driving it in a reciprocating motion, and allowing independent control of the speed and supply pressure in both directions. Double‑acting hydraulic cylinders can be classified as single‑piston‑rod or double‑piston‑rod types.

　　Note: Control systems are more complex than those of single‑acting hydraulic cylinders. Single‑piston‑rod, double‑acting hydraulic cylinders are more common than double‑piston‑rod, double‑acting hydraulic cylinders. Both reciprocating hydraulic cylinders used in machine tools and various motion‑control hydraulic cylinders in construction machinery typically employ single‑piston‑rod, double‑acting designs.