There are many types of single hydraulic props on the market, different types of single hydraulic props are also different features. Everyone knows that the single hydraulic prop is referred to as a single post, which is different from the hydraulic support in structure. There are also differences between internal and external injection type single hydraulic props. Let's talk about the difference between the internal and external injection type single hydraulic prop from the structure and working medium.
The working principle, performance and return mode of the internal and external injection type single hydraulic props are the same, but the structure and working medium are different. Their respective characteristics are as follows:
1) The difference between internal and external injection type single hydraulic props
(1) The working fluid of the externally-injected single hydraulic prop is an emulsion, and the emulsion is discharged to the goaf when returning to the column. The working fluid of the internal injection type single hydraulic prop is hydraulic oil. When returning to the column, the hydraulic oil in the oil cylinder flows back to the inner cavity of the living column to form a closed cycle.
(2) The emulsion for external injection type single hydraulic prop is supplied by the pump station in the roadway through high-pressure hose and injection gun, and the initial support force is given to the prop. The initial support force is guaranteed by the pressure of the pump station. The internal injection type single hydraulic prop is obtained by the prop itself hand pump to obtain the initial supporting force, so the initial supporting force is determined according to the magnitude of the operating force.
(3) The external injection type single hydraulic prop is based on the dead weight of the living column and the return spring to lower the column. The internally-injected single hydraulic props only rely on their own weight to lower the column.
(4) When the internal injection type single hydraulic prop needs lifting and lowering of the column, air intake and exhaust are required, and a ventilation device is required. External injection is not required.
(5) When the movable column of the externally-injected single hydraulic prop is raised to a large height, it is limited by the limit device. When the movable column of the internally-injected single hydraulic prop rises to a large height, it depends on the amount of oil contained in the movable column to limit the position.
(6) All the valves on the external injection single hydraulic prop are assembled together, which is convenient for downhole replacement and uphole maintenance. The safety valve, one-way valve and unloading valve of the internal injection type single hydraulic prop are installed in different positions and cannot be replaced downhole.
The single hydraulic prop is matched with the metal hinged top beam, which is used for the support of the ordinary mechanized coal mining face; it can also be used in the local area of the fully mechanized mining face, such as the end or temporary support. The single column has no pushing device, integral base and top beam, but the structure of the column itself is more complicated than the prop on the hydraulic support. The single column is also the prop of the constant resistance working type.
The single hydraulic prop is suitable for horizontal or gently inclined coal seams with an inclination angle of less than 250 (when reliable safety measures are adopted, it can also be used in coal seams of 25 ° to 35 °), and requires that the bottom plate should not be too soft, and the roof pressure is obvious. For the surrounding rock conditions that are easy to collapse directly, when a single column is used in the working face with too soft floor, complex geological conditions or layering, corresponding measures should be taken.
The editor talked about the difference in structure and working medium between the internal and external injection single hydraulic props. When you buy, you should pay attention to which one to buy. If you want to buy a single hydraulic prop, the editor recommends Shandong China Coal Group's single hydraulic prop manufacturing plant, which is a manufacturer integrating R & D, manufacturing, sales and service , Welcome new and old customers to visit.
