Classification and operational characteristics of hydraulic pumps

Hydraulic pumps are the power components of a hydraulic transmission system. Driven by an engine or motor, they draw oil from the hydraulic tank, generate pressurized oil, and discharge it to the actuating components.

Operational Characteristics of Hydraulic Pumps

1. Design and Resistance Reduction:

• The design of hydraulic pumps minimizes fluid resistance in the suction line.
• To ensure normal operation, hydraulic pumps must meet the following criteria:
  • The installation height must be within specified limits.
  • The pump speed must be adjusted to the normal operating range.
  • Excessive pressure drops caused by pipelines and oil filters must be avoided.

2. Pressure and Load Relationship:

• The working pressure of a hydraulic pump is directly linked to its load. If the pump's working pressure is zero, the load is also zero.
• The working pressure is influenced by the pump's structure and service life.
  3. Variable Displacement Pumps for Flexibility:
• Variable displacement pumps allow for more flexible hydraulic system adjustments.
• The lifespan of a variable displacement pump depends on its operating conditions.
  • Normal operating speeds are beneficial for longevity.
  • High-speed operation increases wear and significantly reduces service life.

4. Suction and Discharge Operation:

• The suction and discharge operations of a hydraulic pump are typically performed by the working chamber of the hydraulic system.
• In case of malfunctions, even minor issues must be thoroughly inspected to prevent major safety incidents.

Classification of Hydraulic Pumps

Hydraulic pumps are categorized by structure into the following types commonly used in hydraulic systems: gear pumps, piston pumps, vane pumps.

1. Gear Pump:

• Compact size, simple structure, and low cost.
• Tolerant to oil contamination.
• Disadvantages:
  • The pump shaft experiences unbalanced forces, leading to severe wear.
  • Higher leakage rates.

2. Vane Pump:

• Includes double-acting and single-acting vane pumps.
• Provides uniform flow, smooth operation, and low noise.
• Higher operating pressure and volumetric efficiency compared to gear pumps.
• More complex in structure than gear pumps.
  3. Piston Pump:
• High volumetric efficiency with minimal leakage.
• Suitable for high-pressure applications, commonly used in high-power hydraulic systems.
• Disadvantages:
  • Complex structure with high material and machining precision requirements.
  • Expensive and sensitive to oil cleanliness.