According to their structural configuration, hydraulic cylinders can be classified into four types: piston cylinders, plunger cylinders, oscillating cylinders, and special‑purpose cylinders. Based on their rated pressure, they are further categorized as high‑pressure and ultra‑high‑pressure hydraulic cylinders, medium‑high‑pressure hydraulic cylinders, and medium‑low‑pressure hydraulic cylinders.

1. Cylinder Barrel: The cylinder barrel is the primary component of a hydraulic cylinder. Together with the cylinder head and piston, it forms a sealed chamber that drives the piston’s motion. Typically, the material for the cylinder barrel must exhibit sufficient stiffness and toughness, as well as excellent weldability to facilitate welding. Cylinder‑body blanks are commonly manufactured from cold‑drawn or hot‑rolled seamless steel tubing, and the typical heat‑treatment process involves quenching and tempering. This ensures that, even after prolonged reciprocating operation, the seal remains intact, allowing for secure drilling and clamping.

2. Cylinder Head: The cylinder head is mounted at both ends of the hydraulic cylinder, forming a sealed oil chamber together with the cylinder barrel. In general, its selection should be based on factors such as operating pressure, cylinder connection method, and service environment.

3. Piston rod: The piston rod is the primary component responsible for transmitting force in a hydraulic cylinder. It is typically made from medium-carbon steel (such as… 45 Steel is used as the material. During operation, the piston rod of a hydraulic cylinder is subjected to thrust, tensile forces, or bending moments; therefore, it is essential to ensure its strength. Moreover, the piston rod frequently slides within the guide sleeve, so the fit must be properly matched. Both excessive tightness and looseness can lead to sticking and uneven wear; hence, the piston surface must be smooth, with excellent straightness and roundness. In most cases, the manufacturing process for piston rods typically involves rough turning, tempering, semi‑finishing turning, quenching, pre‑plating grinding, chrome plating, post‑plating grinding, and finally finish turning.

4. Piston: The piston is the primary component that converts hydraulic energy into mechanical energy, and its effective working area directly affects both the force generated by the hydraulic cylinder and its speed of motion. There are various methods for connecting the piston to the piston rod, including snap-ring type, sleeve type, and nut type. When no guide ring is used, the piston is typically made from high‑strength cast iron or ductile cast iron; when a guide ring is employed, the piston is fabricated from high‑quality carbon steel.

5. Guide Sleeve: The guide sleeve provides guidance and support for the piston rod, requiring high fitting accuracy, low frictional resistance, excellent wear resistance, and the ability to withstand the piston rod’s axial load, bending moments, and impact vibrations. It is equipped internally with a sealing assembly to ensure a tight seal between the cylinder barrel and the rod chamber, and externally with a dust seal to prevent contaminants such as dust and rainwater from entering the sealing system and damaging the guide sleeve.

6. Buffering device: When the piston and piston rod move under hydraulic drive, they possess significant momentum. As they approach the end caps and the cylinder bottom, mechanical impact occurs, generating substantial impact pressure and noise. A buffering device is employed to prevent such collisions; it operates by throttling the oil in the low-pressure chamber of the cylinder, converting kinetic energy into thermal energy, which is then carried away from the hydraulic cylinder via the circulating oil. Buffering devices are classified into two types: those with a fixed throttling area and those with a variable throttling area.