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Application of hydraulic threaded cartridge valve in construction machinery

2.1 Application in hydraulic pump

The earliest threaded cartridge valves were used in hydraulic pumps. Because the hydraulic pump needs to integrate the hydraulic valve, which requires the hydraulic valve to be small, so the threaded cartridge relief valve has been developed. It should be said that the threaded cartridge relief valve is the earliest development and application of the earliest threaded cartridge valve, and then the threaded cartridge check valve and the threaded cartridge throttle valve are used in hydraulic pumps. Modern hydraulic pumps have many threaded cartridge valves integrated in them, the structure and schematic diagram of a closed variable pump is shown in Figure 3, there are more than a dozen threaded cartridge valves integrated in them. The screw insert relief valve is used to adjust the maximum pressure of the main hydraulic pump and the refill pump; Threaded cartridge check valve is used to control the opening or cutting of the oil circuit; Threaded plug type stop valve is used to connect A and B oil ports when the system fails, to facilitate the dragging or traction of construction machinery; The screw insert differential pressure relief valve is used to adjust the output pressure of the pump to change with the load pressure. With the continuous progress of threaded cartridge valve technology, a multi-function valve specially designed for pump has been developed, which integrates the functions of 4 valves, such as threaded cartridge relief valve, threaded cartridge differential pressure relief valve, threaded cartridge check valve and threaded cartridge globe valve.

2.2 Application in hydraulic motor

Threaded cartridge valves are also often used in hydraulic motors (especially closed motors). The structure of a closed variable motor has four threaded cartridge valves integrated into it. The screw insert relief valve is used to adjust the oil change pressure of the system; The threaded insert shuttle valve is used to introduce the pressure oil on the high pressure side into the P port of the electromagnetic direction control valve; Threaded insert electromagnetic direction control valve is used for motor displacement control, threaded insert three-position three-way shuttle valve, also known as threaded insert hot oil shuttle valve, connected to both ends of the closed circuit motor. The positive and negative transfer of the system ensures that the high pressure side has a certain amount of oil back to the tank to achieve closed loop cooling.