Current Status of Gear Oil Pumps

Gear oil pumps are widely used in mechanical systems within the petroleum, chemical, marine, and petrochemical machinery industries. Their primary advantages include a simple structure, compact size, lightweight design, excellent self-priming performance, high tolerance to contamination, reliable operation, long service life, ease of manufacturing and maintenance, and low cost. In summary, they are easy to manufacture, user-friendly, simple to maintain, and cost-effective. However, gear oil pumps also have several drawbacks, mainly significant flow and pressure pulsations, high noise levels, fixed displacement, and lower efficiency at high temperatures. In foreign countries, research on variable-displacement gear oil pumps is currently underway.

In recent years, the working pressure of gear oil pumps has significantly increased, with rated pressures reaching 25 MPa and maximum pressures hitting 31.5 MPa. Additionally, there have been numerous structural improvements, particularly the introduction of triple and quadruple gear oil pumps, which partially compensate for the inability to vary displacement. Their range of applications is also continuously expanding; many hydraulic systems that previously relied on axial piston pumps have now transitioned to gear oil pumps.

In some industrially advanced countries abroad, internal gear oil pumps account for a substantial proportion of total production, with the output ratio of internal to external gear pumps approaching 1:1. In China, however, the production volume of internal gear oil pumps remains relatively low. Specifically, involute-profile internal gear oil pumps are still in the research and development stage.

Gear oil pumps are among the earliest hydraulic components manufactured in China, with production ranging from 0.5 MPa to 25 MPa (with a maximum pressure of 31.5 MPa) and flow rates from 2.5 L/min to 400 L/min. With the exception of service life, product performance has approached or reached advanced international levels, and structural innovations have also been achieved. According to incomplete statistics, the models of gear oil pumps produced in China include CB, CB-B, CB-F, KCB, 2CY, YCB, BB-B, NYP high-viscosity gear oil pumps, and NCB high-viscosity gear oil pumps.