Tai Wan JGH use and characteristics of the overflow valve：

The overflow valve is a pressure control valve. Its main function is to control the pressure of the system to protect the safety of the oil pump and the oil circuit system and keep the pressure constant of the oil circuit system.
A 8 millimeter overflow valve is a small, direct operated overflow valve that can be connected to the remote control port of the main overflow valve to achieve remote pressure regulation for the main overflow valve.

The remote control port of the relief valve is connected with the fuel tank when the reversing valve is connected with the oil tank, so that the oil path can be unloaded. At this time the overflow valve plays the role of unloading.

Changing the regulating spring of the relief valve can change the pressure regulating range.
When the handwheel rotates clockwise, the pressure rises, otherwise the pressure drops.

Pilot relief valve

The pilot relief valve is composed of two parts, the main valve and the pilot valve. Pilot valves are similar to direct acting relief valves, but generally they are mostly cone valves (or ball valves). The main valve can be divided into one concentric structure, two concentric structures and three concentric structures.

The three section concentric structure: the main valve core and the valve cover, the valve body and the main valve seat and so on three have the concentric cooperation request, belongs to the three section concentric structure.

The pressure oil enters from the middle inlet of the valve body, and the damping hole on the main valve core enters the upper cavity of the main valve core, and the oil valve cover acts on the channel and the cone hole on the upper hole and on the cone valve. When the inlet pressure is less than the adjustment value of the pilot valve regulating spring, the pilot valve is closed, the effective area ratio of the upper and lower sides of the main valve core is 1.03 to 1.05, the upper side is slightly larger, and the pressure difference on the main valve core and the main valve spring force all make the main valve opening tight and not overflow. When the oil inlet pressure exceeds the pilot valve adjustment pressure, the pilot valve is opened to cause the flow of the main valve core damping hole, the pilot valve port, the main core hole of the main valve core and the outlet of the valve at the lower part of the body of the P well.

The flow loss at the damping hole causes the oil liquid in the main valve core and the lower cavity to increase the pressure difference with the increase of the flow rate of the pilot valve. When the main valve core is on and down, the total pressure difference is enough to overcome the main valve spring force, the main valve weight and the friction, the main valve core is opened. At this time, the oil inlet is directly communicated with the oil outlet (overflow port), causing overflow to maintain system pressure.

The two section concentric structure: the main spool is a cone valve with cylindrical surface. In order to close the main valve with good sealing, the main valve core 1 cylinder guide surface and conical face are well matched with the valve sleeve, and the two concentricity requirements are higher, so it is called the two section concentric. There are no damping holes on the main spool, and three damping holes are respectively arranged on the valve body and the pilot valve body. Its working principle is the same as that of the three concentric pilot relief valve, and only three damping holes are needed from the main valve to the main valve.

DC type overflow valve

The function of the V DC relief valve is that the pressure base in the control system is constant, to achieve voltage regulation, voltage regulation or pressure limiting. V DC type overflow valve working principle: valve core under the effect of spring on the valve body, valve body inlet and oil outlet, oil pressure through the inlet function on the valve core. When the pressure is less than the spring force, the valve core pressure is not moved on the seat and the valve mouth is closed; conversely, the valve core leaves the seat, the valve opening is opened, the oil is returned from the oil outlet to the mailbox, thus ensuring the basic constant pressure of the import. The advantages and disadvantages of the V DC relief valve are simple structure and high sensitivity, but the pressure is greatly influenced by overflow and is not suitable for working under high pressure.