Axial-rod inclined-disc plunger pump

Axial-rod inclined-disc plunger pump

Axial-piston vane-type plunger pumps are classified into two types: pressure-fed and self-priming. Pressure-fed hydraulic pumps generally use a pressurized oil reservoir; alternatively, the pump itself may be equipped with a make-up brake master cylinder that delivers pressurized oil directly to the pump’s inlet. Self-priming hydraulic pumps, on the other hand, possess strong self-priming capability and require no external pressurization for oil supply. For hydraulic filters that rely on system air pressure for oil delivery, it is essential to wait until the hydraulic reservoir has reached the specified operating air pressure before starting the equipment. If the reservoir pressure is insufficient and the equipment is operated under such conditions, the internal components of the hydraulic pump—particularly the slipper shoes—may suffer tensile failure, leading to abnormal wear or damage between the pump’s oscillating plate and the stator.

Radial piston pump

Radial piston pumps can be classified into valve-controlled and shaft-controlled types. Valve-controlled radial piston pumps are characterized by a high equipment failure rate and low efficiency.

Plunger pump

Inferior defects. During the 1970s and 1980s, advanced axial-flow radial piston pumps developed internationally overcame the shortcomings of valve-controlled radial piston pumps. Due to the inherent characteristics of the axial pump design, axial-flow radial piston pumps exhibit superior shock resistance, longer service life, and higher precision compared with axial piston pumps. In these pumps, variable displacement is achieved by adjusting the eccentricity of the motor stator under the combined action of the swashplate and the retaining plunger; the maximum allowable eccentricity typically ranges from 5 to 9 mm, depending on the displacement, resulting in a very short stroke of the variable-displacement element. Moreover, the variable-displacement mechanism is designed for high-pressure control and is regulated by a pressure-reducing valve, thereby ensuring rapid response. The overall axial design also eliminates problems such as uneven wear of the slipper shoes that plague axial piston pumps, significantly enhancing the pump’s ability to withstand impact.

Hydraulic plunger pump

For hydraulic press plunger pumps that rely on standard atmospheric pressure for oil supply, the hydraulic oil filter element must be replaced after each operation, and the equipment should only be operated once the hydraulic tank has reached the specified operating pressure. Axial piston pumps with swash plates are classified into two types: pressure-fed and self-priming. Pressure-fed hydraulic pumps typically use an oil tank maintained at pressure; alternatively, the pump itself may be equipped with a make-up pump that delivers pressurized oil directly to the pump’s inlet. Self-priming hydraulic pumps have strong self-priming capability and do not require external pressurized oil supply. For self-priming plunger pumps, the hydraulic oil level in the filter element must never fall below the lower limit indicated on the oil level gauge; sufficient lubricating oil must always be maintained. The higher the cleanliness of the hydraulic oil, the longer the service life of the pump.

Structural form

Plunger pumps are classified into two principal structural types: axial plunger pumps and radial plunger pumps; because radial plunger pumps

Plunger pump

It is a new type of high-efficiency pump with relatively high technical complexity. With the continuous acceleration of domestic production and manufacturing, radial piston pumps are bound to become an important component of the main applications of piston pumps; for detailed information, see the Baidu Baike entry on radial piston pumps.

The following discussion is limited to axial piston pumps as an example.

Axial piston pumps operate by utilizing the volumetric changes produced through the reciprocating motion of pistons parallel to the drive shaft within piston bores. Because both the pistons and piston bores are annular components, they can be manufactured with very tight fit tolerances, resulting in high volumetric efficiency, stable operation, excellent flow uniformity, low noise, and high pressure capability. However, these pumps are relatively sensitive to contamination by gear oil, have a more complex structure, and incur higher manufacturing costs.