What are the characteristics of plunger pumps? An oil drilling and production equipment manufacturer explains.

　　 Oil drilling and production equipment manufacturers regard plunger pumps as critical components of hydraulic systems. These pumps operate by utilizing the reciprocating motion of plungers within cylinders to vary the volume of the sealed working chamber, thereby achieving oil suction and pressure boosting. Plunger pumps offer numerous advantages, including high rated pressure, compact design, high efficiency, and convenient flow regulation, making them widely used in applications requiring high pressure, large flow rates, and precise flow control, such as hydraulic presses, construction machinery, and marine vessels.

　　Oil drilling and production equipment manufacturers consider the plunger pump to be a type of reciprocating pump, classified as a positive-displacement pump. Its plunger is driven by the eccentric rotation of the pump shaft and moves back and forth in a reciprocating motion. The suction valve and discharge valve are check valves. When the plunger is pulled out, the pressure in the working chamber decreases, causing the discharge valve to close. Once the pressure drops below the inlet pressure, the inlet valve opens, allowing fluid to enter. Conversely, when the plunger is pushed in, the pressure in the working chamber rises, closing the inlet valve; when the pressure exceeds the discharge pressure, the discharge valve opens, permitting fluid to be discharged. As the drive shaft rotates the cylinder, the swash plate draws the plunger out of or pushes it back into the cylinder, thereby completing the suction and discharge cycle. The oil in the working chamber formed by the plunger cylinder bore is connected via the distribution plate to the pump’s suction chamber and discharge chamber. A variable mechanism is used to adjust the tilt angle of the rotating swash plate; by varying this angle, the pump’s displacement can be adjusted.

　　Oil drilling and production equipment manufacturers recognize two representative structural configurations of plunger pumps: axial-plunger pumps and radial-plunger pumps. Given that the radial-plunger pump is a new type of high-tech pump, and with continuous technological advancements, it is bound to become an important component in the application fields of plunger pumps.

　　Oil drilling and production equipment manufacturers generally adopt a design in which the cylinder block rotates and porting is achieved via end-face distribution in inclined-axis axial piston pumps. The end face of the cylinder block is fitted with a friction pair consisting of a bimetallic plate and a steel porting plate, and most such pumps employ planar porting, which facilitates maintenance. The porting plate is one of the critical components of an axial piston pump. During operation, on the one hand, the high-pressure oil in the working chamber pushes the cylinder toward the porting plate; on the other hand, the hydrodynamic pressure of the oil film between the porting plate and the cylinder generates a hydraulic reaction force that causes the cylinder to deflect away from the porting plate.

　　Oil drilling and production equipment manufacturers advise that when the pump is in self-priming mode, if there are leaks in the suction line or significant leaks in the hydraulic cylinders, check valves, or directional control valves within the system, the pressure will fail to build up. Identify the leak points, tighten connections, replace seals, and then increase the pressure. If the relief valve is malfunctioning or its set pressure is too low, the system pressure will not rise; in such cases, the relief valve should be recalibrated or overhauled. Furthermore, if excessive clearance between the hydraulic pump cylinder block and the port plate results in substantial internal leakage—potentially leading to cylinder block rupture in severe cases—the mating surfaces should be regrinded or the hydraulic pump replaced.

　　Oil drilling and production equipment manufacturers believe that if the circuit load continues to increase, the pump pressure will also continue to rise—this is normal. If the load remains constant but the pump pressure exceeds the pressure required by the load, inspect the hydraulic components other than the pump, such as directional control valves, pressure relief valves, drive units, and the return line. If the pressure is excessively high, the safety valve should be adjusted.