FUNDAMENTALS

longwall mining
 

equipment
   

maingate conveyor & boot end
 

Equipment

Maingate Conveyor & Boot End

Because the face moves continuously along the maingate, at a steady rate if operating correctly, the required maingate belt length is continuously changing. To allow for this and to avoid too frequent stoppages to shorten the belt, it is normal for special arrangements to be made at both ends of the belt.

At the face end, a special boot end is installed. Reference has already been made to the attachment of the outbye end of the BSL. The boot is either pushed outbye through this connection along with the maingate drive and BSL when it has to be moved or it may be a self propelled, caterpillar track mounted unit. The boot is anchored against the belt tension by its connection through the BSL or may be wedged to the roof with jacks – it is not pinned or fixed in any other way as is a conventional belt.

The type pushed outbye by the maingate supports will seldom move in a straight line and in order to keep it in line with the belt there are arrangements included on the boot to enable it to be steered and/or to move it sideways to line it up as required. These arrangements normally involve hydraulic cylinders. Levelling jacks are also required.

At the drivehead end of the conveyor it is normal to install a special "Loop Take-up" ("LTU") with a structure much longer than a conventional LTU and also including rollers to allow the bottom belt to fold back over itself a number of times thus greatly increasing the length of belt which can be stored in the LTU. With this arrangement it is only necessary to stop the longwall to remove belting infrequently and this operation can usually be tied in with other planned stoppages (e.g. maintenance).

With the above arrangements it is possible to change the belt length in frequent small increments for a considerable total distance. The conveyor structure is removed in short sections immediately outbye the boot and for this purpose a pinned type of structure (as opposed to bolted) is preferred (for easy removal).