The conveying device of car dumper apron feeders consists of two sprockets and many chains. The supporting device located on the up-link transmission chain and chain plate is the upper supporting wheel, while the supporting device located on the down-link transmission chain and chain plate is the lower supporting wheel. The lower supporting wheel is easily damaged, which will led to a series of interlocking equipment failures. However the disassembly and installation of the lower tug are difficult, resulting in long maintenance time. Therefore it is necessary to find corresponding solutions to this equipment problem.

The existing problem.
1.The contacting part between the lower supporting wheel and the chain plate is easy to accumulate material and the ore powder enters the bearing of the lower tug, resulting in poor lubrication.
2.It is difficult to lubricate and maintain the bottom wheel, which causes the supporting wheel bearing to be locked and damaged.
3.It is not easy to find the wear of the supporting wheel body by spot inspection and the damaged lower tug causes wear damage to the chain plate. The lower supporting wheel is damaged and dropped into the tail of the sprocket, which will also causes the tail sprocket shaft to be pulled off.
4.It is difficult to repair the bottom supporting wheel. It takes eight hours to replace one set of bottom tugboats.
Problem analysis.
The structure of the lower tug is built in, that is, the whole tug is set placed in the frame of apron feeder. Because the design angle of the feeder is too large, when the material piles up on it, the weight borne by the supporting wheel increases, the tug is often buried by the ore powder, resulting in the damage to the supporting wheel and other parts. When the environment is harsh, dust, humidity is large, especially the unloading of large water content of materials in the rainy season operation, mud from the gap in the chain into the supporting wheel. The end of the wheel is sealed by the felt pad, which is only suitable for good working conditions. However, the working environment of the supporting wheel is bad and there are many impurities and mud, which leads to the failure of wool felt seal. Through the inspection of the dead tug, it was found that the main reason was that mud penetrated into the inner part of the tug, which damaged the lubrication of the bearing, causing the bearing to be stuck and the supporting wheel to be damaged. Secondly, because the tug is installed in the feeder, the tug is double-layer spoke plate type and the weight of the tug is difficult to carry. On the one hand, it is difficult fir the staff to find the damaged tugboat, On the other hand, the maintenance personnel need to enter the feeder to remove and install the tug, it takes a lot if time.
Improvement measures.
1.Improvement of tug boat structure. The improved lower tug is composed of a shaft, a cover on the shaft in turn, a baffle, a supporting wheel seat, a sleeve, a end cover and a ball bearing. The lower support plate is connected to the box body of the feeder. Its characteristics lies in: there is an interval between the baffle and the wheel seat.
2.The seal improvement of bearing. Replace the felt pad with a skeleton rubber oil seal. Compared with wool felt, it has long service life, good sealing effect and so on and can better adapt to the harsh working environment of apron feeders.