System for cutting and conveying coal and the like

In a longwall mining operation wherein a takeoff shaft provided with a takeoff conveyor and an access shaft extend crosswise from a longitudinally extending face, a material recovering and conveying system has a chain itself having a longitudinally extending rear stretch extending along the face from a turnaround in the access shaft to a turnaround in the takeoff shaft and a longitudinally extending front stretch extending along the face between the rear stretch and the face. An undriven idler wheel is provided in the takeoff-shaft turnaround over which the chain is engaged between its stretches and a conveyor trough extends between the turnarounds and has a floor formed in the takeoff shaft with a throughgoing outlet hole above the takeoff conveyor. Conveyor/cutting elements on the chain move in the front stretch along the face and in the rear stretch along the trough. A drive motor in the access shaft at the respective turnaround is connected to the chain for advancing it away from the takeoff shaft in the front stretch to scrape material from the face and deposit it in the conveyor trough and for displacing it toward the takeoff shaft in the rear stretch to move the scraped-off material along the trough and deposit it through the outlet hole into the takeoff conveyor.

FIELD OF THE INVENTION 
The present invention relates to a system for cutting a granular mineral 
material like coal and for conveying it from the cutting location. More 
particularly this invention concerns a long-wall mining apparatus. 
BACKGROUND OF THE INVENTION 
A typical longwall mining apparatus such as described in German patent 
documents 3,318,360 of P. Heintzmann, 3,514,439 of G. Blumenthal, 
3,743,239 of G. Blumenthal (U.S. equivalent Pat. No. 4,883,322), and 
4,004,488 of K. Plaga (U.S. equivalent Pat. No. 5,088,796) have a main 
conveyor chain that extends as parallel front and rear stretches along a 
face being worked between a pair of turnaround locations. One of the 
turnaround locations is in a takeoff shaft or heading leading back from 
the face and containing a takeoff conveyor and the other is in an access 
shaft or heading that normally extends parallel to the takeoff shaft. The 
rear stretch of the chain runs in a conveyor trough parallel to the face 
and the front stretch runs along the face being worked. Conveyor/cutting 
elements mounted on the chain are set in the front stretch in a vertical 
position in which they engage the face and plow material off it, and are 
moved in the rear stretch to a horizontal position in the trough where 
they push the recovered material along to the end of the trough where a 
takeoff conveyor extending away from the face in the takeoff shaft carries 
away the recovered material. 
As a rule a main drive is provided in the main takeoff shaft where there is 
substantial room, and an auxiliary drive is provided at the other 
turnaround location in the small access shaft at the other end of the face 
being worked. A separate device at the takeoff-shaft turnaround location 
transfers the material from the conveyor trough to the takeoff conveyor. 
Thus the known devices are fairly bulky and quite complex. This is true 
regardless of the length of the face or whether the device is being used 
to back-cut the face. 
OBJECTS OF THE INVENTION 
It is therefore an object of the present invention to provide an improved 
longwall mining system. 
Another object is the provision of such an improved longwall mining system 
which overcomes the above-given disadvantages, that is which is 
substantially simpler than the prior-art systems. 
SUMMARY OF THE INVENTION 
In a longwall mining operation wherein a takeoff shaft provided with a 
takeoff conveyor and an access shaft extend crosswise from a 
longitudinally extending face, a material recovering and conveying system 
according to this invention has a chain itself having a longitudinally 
extending rear stretch extending along the face from a turnaround in the 
access shaft to a turnaround in the takeoff shaft and a longitudinally 
extending front stretch extending along the face between the rear stretch 
and the face. An undriven idler wheel is provided in the takeoff-shaft 
turnaround over which the chain is engaged between its stretches and a 
conveyor trough extends between the turnarounds and has a floor formed in 
the takeoff shaft with a throughgoing outlet hole above the takeoff 
conveyor. Conveyor/cutting elements on the chain move in the front stretch 
along the face and in the rear stretch along the trough. A drive motor in 
the access shaft at the respective turnaround is connected to the chain 
for advancing it away from the takeoff shaft in the front stretch to 
scrape material from the face and deposit it in the conveyor trough and 
for displacing it toward the takeoff shaft in the rear stretch to move the 
scraped-off material along the trough and deposit it through the outlet 
hole into the takeoff conveyor. 
This system is based on the discovery that when the face is not too long or 
the system is being used to back cut the face, it is possible to do away 
with drives at both ends of the chain. This makes it possible to dump from 
the conveyor trough directly into the takeoff conveyor, completely 
eliminating the need for a separate transfer device. 
According to a feature of the invention the trough floor lies generally on 
a floor at the face and has a region that is upwardly deflected above the 
floor over the takeoff conveyor at the takeoff-shaft turnaround. In 
addition the takeoff conveyor is mounted on the trough at the 
takeoff-shaft turnaround.

SPECIFIC DESCRIPTION 
As seen in FIGS. 1 and 2 a takeoff shaft S and an access shaft A extend 
parallel to each other from a longwall face F from which material is to be 
cut. A chain 7 has a rear conveyor stretch 1 extending in a conveyor 
trough 2 and a front cutting stretch 3 extending between the trough 2 and 
the face F. In the shaft S the chain 7 passes at a turnaround location 5 
around an undriven idler wheel 12 and in the shaft A it passes at another 
turnaround location 6 around a sprocket 15 rotated by a heavy-duty drive 
13 also located in the shaft A. This chain 7 carries elements 9 that are 
erect and carry coal plows or cutters 8 in the front stretch 3 and that 
are recumbent and act as pushers in the trough 2. Thus, as the chain 7 is 
displaced as indicated for the front stretch 3 at arrow D in FIG. 2, 
material is cut from the face F by the cutters 8 and is deposited in the 
trough 2, and then this material is pushed oppositely toward the 
turnaround location 5 in the trough 2. The mine roof is supported by props 
14 behind the advancing longwall face F in the manner well known in the 
art. 
According to the invention as better shown in FIGS. 3 through 6 the trough 
2 is deflected upward above the mine floor at the turnaround location 5 
and has, just upstream of the wheel 12, a hole or port 10 in its bottom 
wall so that the conveyed material can drop out into the upstream end of a 
standard takeoff conveyor 11 that extends back up the takeoff shaft S. 
There is no drive like the drive 13 at the turnaround 5 so that it is 
possible to thus deflect the trough 2 so that it dumps directly into the 
conveyor 11, making possible a clean transfer without any auxiliary 
equipment.