Belt drives, described

At each location, miners observe and remember different events and conditions. At Crosscut 34, for example, Tidwell smelled smoke Blake reported that the shearer was not operating Tidwell noticed flames inby the mandoor Price looked at the belt drive and Cox noticed that the overcast was collapsed. Miners who arrived at the scene in the early stages of the fire focused on the safety of colleagues and thus paid proportionately less attention to the location of the fire. Individuals on the surface were temporally and physically di.stant from events underground. These individuals described how they communicated with miners underground—answering phones and controlling power to stop the spread of the fire. ... 

The weight of material in the buckets on the loaded side of an elevator chain causes the elevator to momentarily mn backwards if, during operation, the power is intermpted or there is a failure in the driving system. Because this could be a ha2ard to operating personnel, as well as damage to the elevator, a backstop, similar to that described for a belt conveyor, should be used. 

Belt Presses Belt presses were fiiUy described in the section on filtration. The description here is intended to cover only the parts and designs that apply expression pressure by a mechanism in adchtion to the normal compression obtained from tensioning the belts and pulling them over rollers of smaller and smaller diameters. The tension on the belt produces a squeezing pressure on the filter cake proportional to the diameter of the rollers. Normally, that static pressure is calculated as P = 2T/D, where P is the pressure (psi), T is the tension on the belts (Ib/hnear in), and D is the roller diameter. This calculation results in values about one-half as great as the measured values because it ignores pressure created by drive torque and some other forces [Laros, Advances in Filtration and Separation Technology, 7 (System Approach to Separation and Filtration Process Equipment), pp. 505-510 (1993)]. 

Electric motors with V-belt intermediate drive display the same failure modes as those described previously. However, the unique V-belt frequencies should be monitored to determine if improper belt tension or misalignment is evident. 

Sometimes the frame is mounted on a sub-frame together with the drive motor, and where necessary a back-drive system, to control the gearbox pinion shaft, which will in turn control the conveyor-to-bowl differential speed. The back-drive system will be described later, but for the present it suffices to say that it is essentially a braking motor or similar device coupled to the gearbox pinion shaft. The main motor is offset from the bowl and drives the bowl by means of a set of V-belts. The back-drive can also be offset, in which case it would be connected with a timing belt. The timing belt is to facilitate more accurate speed control. However the back-drive system can also be mounted direct in line with the pinion of the gearbox. 

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