Support Control System
The various functions of the powered supports are controlled by an electro-hydraulic control system. The simplest method utilises a control valve mounted on each support which is used to operate the functions of that support (lowering and raising legs, support advancement and conveyor push). This method is termed “unit control” and has a major disadvantage in that the operator is located in the powered support whilst it is moving. For this reason this method has been superseeded by more sophisticated systems.
The “adjacent control” method, as the name suggests, allows the operator to control the powered supports from the adjacent unit by using a similar type of control valve. This allows the operator to remain within a support which is set to the roof. This system can be extended so that not only does the adjacent support lower, advance and set to the roof, but once this is completed a signal is transmitted to the next support so that it too can be operated with the operator at the one location. This can be continued for any number of supports but is restricted to a comfortable seeing distance of around 8 to 10 supports. On completion of the advance cycle of this group of supports the operator will walk through to the start of the next group and continue advancement. The type of system is termed “batch control” or “bank control”.
It is also possible to remove the operator from the face completely and allow them to control the supports from a console at the face end. However, in most cases the operation is still carried out on the face because of mining considerations and the requirement to operate supports in conjuction with other face equipment.by