for the motors. When several motor are used simultaneously, the load can be distributed uniformly [15] among the motors. When the temperature in the fluid coupling exceeds 100-140�棬the alloy plunger [16] will melt and the fluid ejects, leaving the fluid coupling rotating without load. Thus, the motor and other units are protected from burning out. During operation, the face conveyor is frequently started under full load and operated under impacts and vibration. Thus, fluid coupling is necessary for the safe operation of the chain conveyor.2-2 Tail End
From the operational point of view, there are the driven and the nondriven tail ends [17] (or return ends ). The nondriven tail end does not have the drive unit. They are also obtainable in two types: one with the roller shaft [18] fixed and the other with the roller shaft located in slide blocks [19] which can be adjusted to apply adequate tension to the chain assembly [20]. The tensional return end is the most popular type.
If the tail end or the tailentry has sufficient height and satisfies the requirements for face-end [21] operations of the cutting machine, it is most advisable to adopt a return end with a drive frame even though there is no need for a driven tail end. This provides a stable return end, which cannot be lifted up so easily. It also eliminates the chain troubles that have been experienced with the small drum diameters in the return end.
The construction and the working principles of the driven return end are similar to those of the driven head except that the return end does not require the minimum height for unloading. As such, the bottom of the driven frame is flat, unlike that of the driven head, the bottom of which slopes upward. Therefore, the drive frame of the driven return end is short and in practice it can be connected to the line pan either or through an adjusting pan.
2-3 Pans
Although extremely simple in structure, the pans are the major component of the conveyor. There are numerous pieces of pans in a conveyor. They serve as the supporting structure and moving roadway for the flight bars and the loaded coal. It also acts as the guide rail for the cutting machine and therefore subject to high resistance and wear [22]. All of these require that the pans must be strong, rigid and highly wear-resistant.
The pans in an armored face chain conveyor are divided into the following types: line or standard pans [23], ramp or connecting pans, adjusting pans, and split pans [24].
2-4 Spill Plates and Ramp Plates
A. Spill Plates
Spill Plates are used primarily to prevent the coal from spilling over the gob side of the conveyor and to enlarge the cross-sectional area of coal loading in order to increase the carrying capacity of the conveyor. On the gob side of the spill plate, water pipes, hydraulic tubing, and communication devices can be installed safely and conveniently. In addition, guide chan
��һҳ[1][2][3][4]��һҳ
