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Structure, Typology and Engineering Principles of Hydraulic Cylinders in Agricultural Machinery

Structure, Typology and Engineering Principles of Hydraulic Cylinders in Agricultural Machinery


Structure, Typology and Engineering Principles of Hydraulic Cylinders in Agricultural Machinery

In the mechanical performance of agricultural machinery, hydrostatic power transmission systems play a central role. Hydraulic cylinders, which are the linear motion transmission elements of these systems, are critical components that perform functions such as lifting, steering, compression and pushing in agricultural mechanisms with high force transmission. Correct sizing and selection of hydraulic cylinders; They are decisive elements in engineering design in terms of safety, efficiency and system life.

Hydraulic cylinders used in agricultural machinery are engineering components that directly affect the performance of the system in terms of power transmission and motion control. Determination of the appropriate cylinder type and size; It should be based on engineering analysis of numerous variables such as load type, system pressure, motion requirement and installation conditions. A properly selected and properly maintained hydraulic cylinder ensures maximum efficiency and long system life in agricultural production.

Structure and Working Principle of Hydraulic Cylinder

Hydraulic cylinders are linear motion transmission components operating within the framework of Pascal's principle. The pressurized hydraulic fluid acts on the piston surface in a sealed closed volume, creating a linear force. A typical cylinder consists of the following basic components:

  • Cylinder Barrel: The main structure in which the hydraulic fluid is pressurized.
  • Piston (Piston): An intermediate element that converts fluid pressure directly into force.
  • Piston Rod: Transmits the linear motion connected to the piston to the external system.
  • Rod End and Body End Connections: Ends required for load transfer and mechanical assembly (e.g. clevis, cross tube).
  • Sealing Elements: Gaskets and seals to prevent hydraulic leaks and prevent external leakage.

The force generated by the cylinder is:

F=P×AF=P×A

Here:

  • FF: Force generated by the cylinder (N)
  • PP: Hydraulic Fluid Pressure (Pa)
  • AA: Piston area (m²)

Hydraulic Cylinder Types Used in Agricultural Machinery

Cylinders used in agricultural applications are classified according to the mode of mechanical attachment, stroke characteristic and class of service:

Clevis Tipped Cylinders

  • Mounting: U profile end structure connected movable by pin.
  • Usage: Tractor three-point suspension systems.
  • Advantage: Ability to swing freely in horizontal and vertical planes.

Cross Tube Silindirler

  • Mounting: Fastening to the ends of the cylinder by welded horizontal tube passage.
  • Usage: Dump trailers, loader arms.
  • Advantage: Provides structural stability in load distribution.

Tang Tip Cylinders

  • Mounting: Fixed flat ears welded to the ends of the cylinder.
  • Use: Heavy-duty applications (e.g. deep tillage).
  • Advantage: High static strength, low maintenance.

Tie-Rod Cylinders

  • Structure: Modular structure clamped with shafts (tie-rods) surrounding the body.
  • Advantage: Easy maintenance, economical solution in low pressure systems.
  • Disadvantage: High pressure and impact resistance are limited.

Telescopic Cylinders

  • Structure: It has a multi-stage piston system that intertwines.
  • Usage: Damper systems, applications requiring high stroke.
  • Advantage: Long travel distance is ensured in a compact volume.

Design and Selection Criteria of Hydraulic Cylinders

The following engineering parameters should be taken into account when selecting the cylinder in line with its function in the system:

Criteria

Explanation

Diameter (Bore Ø)

It determines the generation of force. As the area increases, the force increases.

Stroke Length

It is determined by the required linear travel distance.

Piston Rod Diameter

It is important for bending resistance and column strength.

Working Pressure (bar)

It must be suitable for the working pressure of the hydraulic system.

Tipi Fitting

Must be compatible with the mechanical system (e.g. clevis, trunnion).

Port Configuration

Fluid inlet outlet connection position and type.

Column Load

Axial load on the piston under external load.

Reversible or Single Acting

Operating characteristic. If high sensitivity is desired, double-acting is preferred.

Note: System pressures between 160-250 bar are generally common in agricultural machinery. However, in heavy-duty applications, this value can be up to 300 bar.

Application Engineering and Maintenance Principles for Hydraulic Cylinders

The following engineering practices are recommended for hydraulic cylinders to work with long life and high performance in agricultural equipment:

  • Axial Alignment: The cylinder assembly must be on the same axis as the load line. Otherwise, the piston rod runs the risk of bending.
  • Outdoor Protection: Chrome-plated piston rod and sealing systems should be preferred to protect against dust, mud and chemical effects.
  • Filtration: Oil cleaning in the hydraulic system determines the life of the sealing elements.
  • Liquid Filling: Cylinders are usually shipped dry. It must be filled with filtered oil of suitable viscosity before it can be integrated into the system.