Working principle of hydraulic support
The hydraulic support must have four basic actions of raising, lowering, pushing, and moving during the working process. These actions are performed by using high pressure emulsion provided by the pump station through several hydraulic cylinders with different working properties.
Lifting column: When the hydraulic support is needed to lift and support the top plate, the high-pressure emulsion enters the lower piston cavity of the column, and the other cavity returns to the liquid to push the piston up. The top beam connected to the piston rod tightly contacts the top plate.
Descending column: When the descending column is needed, the high-pressure emulsion enters the upper piston cavity of the column, and the other cavity returns to the liquid, pushing the piston down, and the top beam comes out of contact to contact the top plate.
Moving the support and the conveyor forward: The moving of the support and the conveyor is done by the pushing jack on the base. When the bracket needs to be moved forward, the column is first unloaded, and then the high-pressure liquid enters the piston rod cavity that moves the jack, and the other cavity returns to the liquid. The conveyor is used as the fulcrum, and the cylinder is moved forward to pull the entire bracket to the coal wall. When the conveyor is pushed, after the support supports the top plate, the high-pressure liquid enters the lower cavity of the pushing jack, and the other cavity returns to the liquid. With the bracket as the fulcrum, the piston rod is extended to push the conveyor toward the coal wall.
When the support column works, the change of its supporting force with time can be divided into three stages: when the support column is lifted, high pressure liquid enters the lower cavity of the column, the column rises to make the top beam contact the top plate, and the pressure in the lower cavity of the column increases. At the working pressure of the station, the pumping station is automatically unloaded, the hydraulic control check valve of the bracket is closed, and the pressure in the lower cavity of the column reaches the initial supporting force. The pressure increases until the pressure of the bracket safety valve is adjusted, and the pressure in the lower chamber of the column reaches the working resistance. This stage is the phase of increasing resistance. As the pressure of the top plate continues to increase, it is the time when the pressure in the lower chamber of the column exceeds the pressure of the safety valve. When the safety valve opens to overflow and the column shrinks, the pressure on the top plate decreases and the pressure in the lower cavity of the column decreases. When it is lower than the pressure adjustment value of the safety valve, the safety valve stops overflowing, so under the limit of the pressure adjustment of the safety valve, the pressure The curve changes in a wave shape with time, and this stage is a constant resistance stage.