As the name indicates, Last-Chance filters offer the last opportunity for filtration directly prior to the inflow into the component to be protected They are installed into the pressure pipe directly in front of the control valves.
Filtration at the safety shields
In underground mining, all excavated hollow spaces must be supported against the soil or rock layers above them to prevent collapses and danger to people and machinery. In modern mines, hydraulically-operated, self-propelled roof support shields are used, which follow the mining machine and are directly adjusted to the respective height of the seam.
Depending on the length of the shield alignment the supports can be controlled hydraulically, electro-hydraulically, or electrically. All hydraulic fluids used in the roof support shields are continuously filtered. This is done by in-line filters and back-flush filters which are applied directly at the point of use. The selection of filters and the type of back-flushing are individually adapted to the required face height.
As well as the Last-Chance filters, bypass-filters are also used to protect the fluid.in hydraulic circuits. This means that all valves and sensitive components are protected against impurities that could cause abrasion or blockages.